Clinical Evidence

More than 300 000 surgeries have been conducted using Inion® implants since 2001. Several scientific publications demonstrate the safety and efficacy of the Inion® implants. Here, we have collected evidence-based pre-clinical and clinical references, in vitro and biomechanical studies as well as literature reviews mentioning the application of Inion® products in published peer-reviewed journals. The references help health professionals to improve their understanding of clinical outcomes of Inion® products in their work.

The citation information, abstracts and article links are listed below by application and product line. You can find the list of references by product line by clicking the product name.


Inion FreedomPin™


Biodegradable Fixation Pins for Interphalangeal Joint Arthrodesis in Lesser Toe Deformity and Fracture Correction – A Retrospective Follow-up of 31 Toes, Koivu and Koski (2023).
Foot & Ankle Surgery: Techniques, Reports & Cases, 2023, 100272, ISSN 2667-3967.

Lesser toe deformities are commonly surgically treated with interphalangeal joint arthrodesis using different internal fixation implants with good results. There are few studies reporting the results of the use of bioabsorbable implants. The aim of this study was to investigate the clinical and radiological outcomes of lesser toe interphalangeal joint arthrodesis using a novel biodegradable pin as fixation method. Consecutive patients operated by proximal (PIPJ) or distal interphalangeal joint (DIPJ) arthrodesis using the Inion FreedomPin™ (Inion Oy, Tampere, Finland) with a minimum of 12 months of follow-up were retrospectively evaluated both clinically and radiologically. 21 patients (age 34-78, median 60 years) with 24 feet and 31 toes were available with a median follow-up of 26 (range 12-40) months. Clinical alignment was good in all but one toe. There were no complications and patient satisfaction was high. The radiological alignment was corrected in 25, partially corrected in five, and not corrected in one toe. A complete radiological bony fusion was detected in 25 (81 %), partial in one (3 %), and no fusion in five (16 %) toes. In conclusion, the Inion FreedomPin™ bioabsorbable pin had clinically and radiologically favourable outcome for lesser toe interphalangeal joint arthrodesis.

Link to the article


Inion FreedomPlate™


Lateral wall osteotomy combined with embedded biodegradable implants for displaced intra-articular calcaneal fractures, Yang et al. (2019).
Orthop Surg Res. 2019 Mar 6;14(1):74.

Background: The extensile lateral approach (ELA) has been widely used to treat displaced intra-articular calcaneal fractures (DIACFs) and remains the gold standard procedure. Orthopedic surgeons are extremely concerned of the high rate of wound complications. This study intended to report a new surgical technique of the lateral wall osteotomy combined with an embedded biodegradable implant for treating DIACFs and assess clinical and radiological results.

Methods: From May 2013 to December 2015, a total of 17 patients with 19 calcaneal fractures underwent surgical treatment using our new technique. Radiographic images, computed tomography (CT) scans, and magnetic resonance (MR) images of the operative limb were obtained to assess fracture healing and biodegradable implant degradation. American Orthopaedic Foot and Ankle Society (AOFAS) ankle/hindfoot score at the last follow-up was obtained to assess functional result for all cases. Böhler’s and Gissane’s angles, width, and height of the injured calcaneus were analyzed using preoperative and last follow-up radiographic images.

Results: All radiological parameters were significantly improved at the last follow-up, with an increase of 15.58°, 8.38°, and 7.65 mm in Böhler’s angle, Gissane’s angle, and calcaneal height, respectively, and a decrease of 2.51 mm in calcaneal width (p < 0.05). Mean AOFAS score at the last follow-up was 84.37 ± 9.98, with 9, 6, and 4 feet, having excellent, good, and fair rates, respectively. None had nonunion, delayed union, or malunion after a mean follow-up of 34.69 ± 5.22 months. One superficial infection occurred 6 days post-surgery.

Conclusions: Osteotomy of the lateral wall of the calcaneus allows tension-free suturing and avoids damage to penetrating branches of the lateral calcaneal artery (LCA). Biodegradable implants are easy to reshape and do not require surgical removal. However, they should be limited to Sander’s type II and III fractures only.

Link to the article


Use of an absorbable plate in the management of a clavicle fracture in an adolescent, Edmonds (2012). 
Am J Orthop (Belle Mead NJ). 2012 Jan;41(1):29-32. 

Management of clavicle fractures continues to evolve. Indications for operative management seem to be expanding, particularly in athletic youth. Surgical intervention has potential complications, many associated with use of metal implants. To my knowledge, this case report is the first to describe use of a biodegradable implant. The subcutaneous position of the clavicle makes it ideal for fixation with a biodegradable implant in which no second surgery is required for implant removal.

Link to the article


Outcomes of operative treatment of unstable ankle fractures: a comparison of metallic and biodegradable implants, Noh et al. (2012). 
J Bone Joint Surg Am. 2012 Nov 21;94(22):e166.

Background: Biodegradable implants for internal fixation of ankle fractures may overcome some disadvantages of metallic implants, such as imaging interference and the potential need for additional surgery to remove the implants. The purpose of this study was to evaluate the outcomes after fixation of ankle fractures with biodegradable implants compared with metallic implants.

Methods: In this prospectively randomized study, 109 subjects with an ankle fracture underwent surgery with metallic (Group I) or biodegradable implants (Group II). Radiographic results were assessed by the criteria of the Klossner classification system and time to bone union. Clinical results were assessed with use of the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale, Short Musculoskeletal Function Assessment (SMFA) dysfunction index, and the SMFA bother index at three, six, and twelve months after surgery.

Results: One hundred and two subjects completed the study. At a mean of 19.7 months, there were no differences in reduction quality between the groups. The mean operative time was 30.2 minutes in Group I and 56.4 minutes in Group II (p < 0.001). The mean time to bone union was 15.8 weeks in Group I and 17.6 weeks in Group II (p = 0.002). The mean AOFAS score was 87.5 points in Group I and 84.3 points in Group II at twelve months after surgery (p = 0.004). The mean SMFA dysfunction index was 8.7 points in Group I and 10.5 points in Group II at twelve months after surgery (p = 0.060). The mean SMFA bother index averaged 3.3 points in Group I and 4.6 points in Group II at twelve months after surgery (p = 0.052). No difference existed between the groups with regard to clinical outcomes for the subjects with an isolated lateral malleolar fracture.

Conclusions: The outcomes after fixation of bimalleolar ankle fractures with biodegradable implants were inferior to those after fixation with metallic implants in terms of the score on the AOFAS scale and time to bone union. However, the difference in the final AOFAS score between the groups may not be clinically important. The outcomes associated with the use of biodegradable implants for the fixation of isolated lateral malleolar fractures were comparable with those for metallic implants.

Link to the article


Fixation properties of a biodegradable “free-form” osteosynthesis plate with screws with cut-off screw heads: biomechanical evaluation over 26 weeks, Väänänen et al. (2009).
Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 2009: No4, Vol.107.

Objective: The aim of this study was to compare the postoperative fixation properties of a biodegradable osteosynthesis “free-form” plate achieved with countersunk screws with those provided by screws with cut-off screw heads.

Study design: Acrylic pipes were fixed together to simulate fracture fixation for tensile testing. Additional plates were fixed to a polyurethane block with a single screw for plate-screw pullout testing. Specimens were incubated in phosphate buffer solution at 37 degrees C, and testing was conducted at various time points during hydrolytic degradation of 26 weeks. In both tests the specimens were loaded at a speed of 5 mm/min until failure. The yield load, maximum load, and stiffness were recorded, and failure mode was visually determined.

Results: Both countersunk screws and screws with cut-off screw heads provided similar plate fixation properties over degradation time.

Conclusion: According to these results, fixation of the biodegradable osteosynthesis free-form plate with screws with cut-off screw heads seems to be feasible.

Link to the article


Inion OTPS™ Pin


Bioabsorbable pins for bone fixation in the less invasive innominate osteotomy, Dawson et al. (2014).
J Pediatr Orthop B. 2014 Sep;23(5):426-9.

For the less invasive innominate osteotomy for the treatment of developmental dysplasia of the hip, we aim to report radiological outcomes, complication rates and reoperation rates for patients whose bone grafts were secured using bioabsorbable pins. A retrospective study of all patients who underwent less invasive innominate osteotomy for persistent or delayed diagnosis developmental dysplasia of the hip over a period of 2 years from 2008 to 2010 was carried out. A total of 59 hips were identified as having had their bone graft secured with two bioabsorbable pins made from copolymers of L-lactic acid, D-lactic acid and trimethylene carbonate. The average angular correction of the acetabular index in the bioabsorbable group at late follow-up was 16.48° (P<0.0001). Seven percent of patients from the bioabsorbable pin group went on to require reoperation for persistent dysplasia. No patient required reoperation due to implant failure. There was no incidence of postoperative wound infection or other complication requiring medical or surgical intervention. These results demonstrate that the use of bioabsorbable pins to secure the bone graft is as effective and safe as metal fixation.

Link to the article


Use of bioabsorbable pin in innominate osteotomy for correction of developmental dyplasia of the hip, Chukwunyerenwa et al. (2012).
Orthopaedic Proceedings. Vol. 94. No. SUPP_XXXIX. The British Editorial Society of Bone & Joint Surgery, 2012.

Innominate Osteotomy first described by Salter is one of the commonest procedures performed for treatment of Developmental Dysplasia of the Hip (DDH) in children. We recently described a less invasive technique for Innominate Osteotomy, which significantly reduces the operation time without compromising outcome (J Pediatr Orthop B. 2010 Jul;19(4):318–22). As part of the evolution of this procedure we now routinely use bioabsorbable pins (INION OTPS PIN, made from co-polymers of L-lactic acid, D-lactic acid and trimethylene carbonate) instead of K-wires to secure the graft.

We prospectively followed-up 120 consecutive cases done using bioabsorbale pins over a 2 year period. The surgical technique was as described in our less invasive innominate osteotomy paper. Average age at surgery was 24 months (18–52) with mean follow-up period of 15 months (6–24 months). The mean preoperative acetabular index was 36.2o. Our results show a mean acetabular index of 18.7o (P< 0.0001) at latest follow-up with no loss of correction. We recorded three superficial wound infections (one MRSA), all resolved uneventfully. There was no foreign body reaction.

The use of bioabsorbable pins eliminates the need for a second anaesthetic to remove the pins with significant cost benefit without compromising outcome.

Link to the article


Knee osteochondral fractures in skeletally immature patients: French multicenter study, Chotel et al. (2011).
Orthop Traumatol Surg Res. 2011 Dec;97(8 Suppl):S154-9.

Introduction: Femoral or patellar osteochondral fractures complicating patellar dislocation are more frequently observed in adolescents than in adults. These incidental lesions of vulnerable joint cartilage are often neglected in the initial phase, which is regrettable given their good capacity for healing after repositioning. The objective of this study was to investigate the characteristics and analyze the results of repositioning these fractures in skeletally immature patients.

Material and methods: This retrospective multicenter study grouped 14 patients and knees (seven females). The mean age at the time of the accident was 12.9 years (range, 11.2-14.9 years) for the girls and 14 years (range, 12.2-15 years) for the boys. These fractures involved the lateral condyle in nine cases and the patella in five cases. The injury mechanism was secondary to demonstrated patellar dislocation (n=9) or a direct impact (n=4). In nine cases out of 14, a leisure sports accident was the cause. The injury was treated a mean 5.2 days (range, 0-20 days) after the accident. All of the detached fragments were repositioned surgically with screw fixation (n=5), resorbable pins (n=5), or pull-out suture (n=4). Biological glue was added for six patients. Patellar stabilization was associated during the same procedure in two cases.

Results: No postoperative complications were observed. The results at the mean follow-up of 30 months (range, 15-89 months) showed no revision for failure, with all of the fractures demonstrating union at the final examination. The mean IKDC 2000 subjective score was 88±6 (range, 79-98) out of 100 points. The subjective satisfaction level was very satisfied in two cases and satisfied in the 12 others. The final IKDC score was A for eight patients, B for five patients, and C for one patient. Three patients underwent secondary patellar stabilization surgery.

Conclusion: Better knowledge of this fracture and attentive reading of the radiographic images of a knee with hemarthrosis should result in more frequent diagnosis of this condition and adapted treatment. Unexplained hemarthrosis in a context of trochlear dysplasia should be considered to be associated with an OCF until proof of the contrary. A fragment released in a weightbearing zone should ideally be repositioned within 10 days but remains possible at 2 months. It regularly provides bone union and good results in children.

Link to the article


Early experience with biodegradable implants in pediatric patients, Mavrogenis et al. (2009).
Clin Orthop Relat Res. 2009 Jun;467(6):1591-8.

We retrospectively studied nine children and adolescents with congenital malformations, large reconstruction after tumor excision, fractures and osteotomies of the upper extremity, and hand trauma with bone and soft tissue defects treated by internal synthesis using a biocopolymer of L- and DL-stereoisomers of lactic acid polymers and trimethylenecarbonate. A total of 52 biodegradable implants were placed in bone. At a minimum followup of 7 months (mean, 17 months; range, 7-22 months), wound healing was uncomplicated; local or systemic inflammatory tissue reactions, foreign body reactions, and infections were not observed. Bone healing was complete. Six biodegradable screws broke during insertion because of inadequate drilling and tapping, and three biodegradable screws had to be replaced because of damage to the screw head during assembly with the screwdriver. Biodegradable copolymers of poly-L-lactic-poly-DL-lactic acid and trimethylenecarbonate can be used safely and effectively for reconstruction and fixation of bone in children and adolescents.

Link to the article


Internal Fixation of Osteochondritis Dissecans in the Knee, Penton and Cascio (2008).
Operative Techniques in Sport Medicine 16:97-101.

Osteochondritis dissecans (OCD) often requires rigid fixation to promote healing. Whether through an arthroscopic or open approach, the basic principles of fixation remain including anatomic reduction, restoration of cartilage congruity, rigid fixation, and enhancement of the blood supply to the lesion. Internal fixation of OCD has evolved through the years with the development of newer methods of fixation. Early fixation was accomplished through the use of wires, which had the potential to bend and break or migrate, often provided little compression, and eventually had to be removed with a second operation. Later AO and cannulated screws provided the advantage of compression and they could be placed antegrade or retrograde but, like wires, eventually had to be removed. Variable-pitch screws have many of the benefits of standard screws, including compression of the lesion and cannulated options. However, they are headless and can be countersunk in the lesion, obviating the need for removal most of the time. Finally, bioabsorbable implants including nails, pins, and variable-pitch screws provide low-profile designs, bioabsorbable properties, compression of the lesion, and decrease in stress shielding of the lesion. An early reported complication of reactive synovitis has been less common with newer polymers and generally resolves with aspiration. This article discusses the options for internal fixation of OCD lesions.

Link to the article


Inion OTPS™ Plating system


Comparative study between osteosynthesis in conventional and bioabsorbable implants in ankle fractures, Gaiarsa et al. (2015).
Acta Ortop Bras. 2015 Sep-Oct;23(5):263-7.

To compare the functional results of ankle fractures treated with metallic and absorbable plates. Twenty patients were randomized into two groups (metallic and absorbable implant groups) and followed prospectively. In the immediate postoperative period, patients were immobilized with plaster casts for one week, which was replaced by a removable cast for another four weeks. Partial weight-bearing was allowed after three weeks, and full weight-bearing after six weeks. Functional recovery was similar in both groups. At six months, three patients in the metallic group complained of local pain, and had their implants removed. One patient in the absorbable group exhibited early dehiscence of the suture and underwent debridement and suturing with good evolution. The American Orthopaedic Foot and Ankle Society (AOFAS) score was similar between the two groups after six and nine months of follow-up. The absorbable implants showed clinical and functional results that were similar to those of metallic implants. Level of Evidence II, Prospective Comparative Study.

Link to the article


A retrospective follow-up of ankle fracture patients treated with a biodegradable plate and screws, Kukk and Nurmi (2009).
Foot Ankle Surg. 2009;15(4):192-7.

Background: Biodegradable fixation implants have been developed to avoid secondary hardware removal. The aim of this study was to retrospectively follow-up ankle fracture patients treated with a biodegradable plate and screws, and to evaluate the clinical outcome and occurrence of complications.

Methods: Fifty-seven ankle fracture patients treated with biodegradable implants were invited, and a total of 50 were available to participate in this study. The follow-up included a review of each patient’s medical records, evaluation of radiographs, fracture reduction classification, and functional scoring.

Results: There were 36 lateral malleolar and 14 bimalleolar fractures. No perioperative complications occurred. Average follow-up time was 17 months. All fractures healed. Fracture alignment was classified as anatomical in 49 patients and good in 1 case. The mean Olerud and Molander functional ankle score at final follow-up was 86. Eight patients had postoperative complications. These included delayed wound healing in 1 case, 3 cases of deep-vein thrombosis, and 4 soft tissue reactions.

Conclusions: According to the results of this retrospective study, the biodegradable implants used yielded fracture healing and functional results comparable to those previously reported after conventional metal fixation.

Link to the article


Inion OTPS™ Mesh


The use of a biodegradable mesh plate to augment grafting of an acetabular defect: Laboratory investigation and clinical pilot study, Väänänen et al. (2010).
J Bone Joint Surg Br. 2010 Jan;92(1):179-85.

We used a biodegradable mesh to convert an acetabular defect into a contained defect in six patients at total hip replacement. Their mean age was 61 years (46 to 69). The mean follow-up was 32 months (19 to 50). Before clinical use, the strength retention and hydrolytic in vitro degradation properties of the implants were studied in the laboratory over a two-year period. A successful clinical outcome was determined by the radiological findings and the Harris hip score. All the patients had a satisfactory outcome and no mechanical failures or other complications were observed. No protrusion of any of the impacted grafts was observed beyond the mesh. According to our preliminary laboratory and clinical results the biodegradable mesh is suitable for augmenting uncontained acetabular defects in which the primary stability of the implanted acetabular component is provided by the host bone. In the case of defects of the acetabular floor this new application provides a safe method of preventing graft material from protruding excessively into the pelvis and the mesh seems to tolerate bone-impaction grafting in selected patients with primary and revision total hip replacement.

Link to the article


Surgical stabilization of rib fractures using Inion OTPS wraps–techniques and quality of life follow-up, Campbell et al. (2009).
J Trauma. 2009 Sep;67(3):596-601.

Background: A variety of operative techniques have been described in the past for the surgical stabilization of fractured ribs.

Methods: From February 2004 to November 2008, consecutive patients who underwent open reduction and internal fixation of traumatic fractured ribs during their index admission using the Inion orthopedic trauma plating system (OTPS) at a Level I trauma center were retrospectively analyzed. Demographics, Injury Severity Scores, number and site of rib fractures, operative details, and complications were recorded. All patients were followed-up with a questionnaire assessing chest symptoms, disability, and quality of life.

Results: Thirty-two patients underwent surgical stabilization with Inion OTPS. Road crashes were the commonest mechanism of injury (81%), followed by falls. Seventy-two percent of patients were male, with a median age at operation of 53 years (interquartile range [IQR], 40-64 years). Median number of ribs fixed was 3 (IQR, 2-4), while median number of fractures was 9 (IQR, 6-13). Median time to fixation was 5 days (IQR, 3-7 days), intensive care unit stay 3 days (IQR, 0.8-6.3 days), and total hospital stay 13.5 days (IQR, 8.8-22 days). Wound infection occurred in 19%, with nonunion of a fixed fracture in one patient. Sixty-three percent of patients completed the survey with a mean time between open reduction and internal fixation and questionnaire of 1,039 days (+/-480 days). Patients reported low levels of pain at rest and with coughing (median at rest 1.0/10 [IQR, 0-2.3/10]; with coughing 1.3/10 [IQR, 0-3.75/10]). Chest wall stiffness was experienced by 60% of patients, while dyspnoea at rest was reported by 20% of patients. Mean return to work (for 55%) was 3.9 months (+/-3.3 months). All patients were satisfied with the results of their operation.

Conclusion: Patients demonstrated low levels of pain and satisfactory rehabilitation. The Inion OTPS system has several advantages including gradual transference of stress loads to bone, micromotion across the fracture site, and easy wrapping of comminuted fractures. This technique allows excellent stabilization of fractured ribs, with good clinical results in ambulant and ventilated patients, both with initial and with midterm follow-up.

Link to the article


Inion OTPS™ Screw


Resorbable osteosynthetic devices in pediatric traumatology: a prospective series of 24 cases, Poircuitte et al. (2015).
Eur J Orthop Surg Traumatol. 2015 Aug;25(6):997-1004.

Bioresorbable devices are commonly used in traumatology. The biomechanical stability of these materials has improved in the past decade, and they have proven to be biologically non-hazardous, while their main advantage is that their use avoids reintervention for removal of the device. A prospective monocentric study was conducted: 24 patients presenting with a fracture that was amenable to osteosynthesis by small-diameter screws were included. These comprised ten tibial spine fractures, four osteochondritis dissecans of the distal femur, eight fractures of the medial epicondyle of the distal humerus, and two distal tibial apophyseal fractures. One or more screws were used that were made of a copolymer of poly-L-lactide-poly-D-lactide acid and trimethylene carbonate with a diameter of 2.8 mm. All patients were immobilized with a cast. Clinical and radiographic monitoring was conducted every month. The entire follow-up protocol had a duration of 24 months. One patient with osteochondritis dissecans presented with joint effusion. Joint stiffness at the time of cast removal resolved completely after 4 months, except for with three children (one epicondyle fracture, two tibial spine fractures). No subjective or objective instability could be detected by clinical examination. Radiographic follow-up revealed no secondary displacement, and all of the fractures had healed. No osteolysis was seen around the screws. No growth disturbances were noticed. Bioresorbable materials thus appear to be a suitable alternative approach for certain pediatric fractures. Their use resulted in outcomes similar to traditional techniques in terms of functional properties and bone healing. Although initial costs are presumably slightly higher, by avoiding a removal operation the total financial burden is most likely reduced.

Link to the article


Sports Medicine

Inion Hexalon™


Femoral and Tibial Tunnel Diameter and Bioabsorbable Screw Findings After Double- Bundle ACL Reconstruction in 5-Year Clinical and MRI Follow-up, Kiekara et al. (2017).
Orthop J Sports Med. 2017 Feb 2;5(2):2325967116685525.

Background: Tunnel enlargement is frequently seen in short-term follow-up after anterior cruciate ligament reconstruction (ACLR). According to new evidence, tunnel enlargement may be followed by tunnel narrowing, but the long-term evolution of the tunnels is currently unknown.

Hypothesis/purpose: The hypothesis was that tunnel enlargement is followed by tunnel narrowing caused by ossification as seen in follow-up using magnetic resonance imaging (MRI). The purpose of this study was to evaluate the ossification pattern of the tunnels, the communication of the 2 femoral and 2 tibial tunnels, and screw absorption findings in MRI.

Study design: Case series; Level of evidence, 4.

Methods: Thirty-one patients underwent anatomic double-bundle ACLR with hamstring grafts and bioabsorbable interference screw fixation and were followed with MRI and clinical evaluation at 2 and 5 years postoperatively.

Results: The mean tunnel enlargement at 2 years was 58% and reduced to 46% at 5 years. Tunnel ossification resulted in evenly narrowed tunnels in 44%, in conical tunnels in 48%, and fully ossified tunnels in 8%. Tunnel communication increased from 13% to 23% in the femur and from 19% to 23% in the tibia between 2 and 5 years and was not associated with knee laxity. At 5 years, 54% of the screws were not visible, with 35% of the screws replaced by a cyst and 19% fully ossified. Tunnel cysts were not associated with worse patient-reported outcomes or knee laxity. Patients with a tibial anteromedial tunnel cyst had higher Lysholm scores than patients without a cyst (93 and 84, P = .03).

Conclusion: Tunnel enlargement was followed by tunnel narrowing in 5-year follow-up after double-bundle ACLR. Tunnel communication and tunnel cysts were frequent MRI findings and not associated with adverse clinical evaluation results.

Link to the article


Double-Bundle Versus Single-Bundle Anterior Cruciate Ligament Reconstruction: A Prospective Randomized Study With 10-Year Results, Järvelä et al. (2017).
The American Journal of Sports Medicine. 2017; 45(11):2578-2585.

Background: A long-term follow-up comparing double-bundle and single-bundle techniques for anterior cruciate ligament (ACL) reconstruction has not been reported before.

Hypothesis: Double-bundle ACL reconstruction may have fewer graft ruptures, lower rates of osteoarthritis (OA), and better stability than single-bundle reconstruction.

Study design: Randomized controlled trial; Level of evidence, 2.

Methods: Ninety patients were randomized for double-bundle ACL reconstruction with bioabsorbable screw fixation (DB group; n = 30), single-bundle ACL reconstruction with bioabsorbable screw fixation (SBB group; n = 30), and single-bundle ACL reconstruction with metallic screw fixation (SBM group; n = 30). Evaluation methods consisted of a clinical examination, KT-1000 arthrometer measurements, International Knee Documentation Committee (IKDC) and Lysholm knee scores, and a radiographic examination of both the operated and contralateral knees.

Results: Eighty-one patients (90%) were available at the 10-year follow-up. Eleven patients (1 in the DB group, 7 in the SBB group, and 3 in the SBM group) had a graft failure during the follow-up and went on to undergo revision ACL surgery ( P = .043). In the remaining 70 patients at 10 years, no significant group differences were found in the pivot-shift test findings, KT-1000 arthrometer measurements, or knee scores. The most OA findings were found in the medial compartment of the knee, with 38% of the patients in the operated knee and 28% of the patients in the contralateral nonoperated knee. However, no significant group difference was found. The most severe OA changes were in the patients who had the longest delay from the primary injury to ACL reconstruction ( P = .047) and in the patients who underwent partial meniscal resection at the time of ACL reconstruction ( P = .024).

Conclusion: Double-bundle ACL reconstruction resulted in significantly fewer graft failures than single-bundle ACL reconstruction during the follow-up. Knee stability and OA rates were similar at 10 years. The most severe OA changes were found in the patients who had the longest delay from the primary injury to ACL reconstruction and in the patients who underwent partial meniscal resection at the time of ACL reconstruction.

Link to the article


Tibial and Femoral Tunnel Changes After ACL Reconstruction, Weber et al. (2015).
The American Journal of Sports Medicine. 2015; Vol. 43, No. 5.

Background: Tunnel widening after anterior cruciate ligament reconstruction (ACL-R) is a well-accepted and frequent phenomenon, yet little is known regarding its origin or natural history.

Purpose: To prospectively evaluate the cross-sectional area (CSA) changes in tibial and femoral bone tunnels after ACL-R with serial MRI.

Study Design: Case series; Level of evidence, 4.

Methods: Patients underwent arthroscopic ACL-R with the same surgeon, surgical technique, and rehabilitation protocol. Each patient underwent preoperative dual-energy x-ray absorptiometry and clinical evaluation, as well as postoperative time zero MRI followed by subsequent MRI and clinical examination, including functional and subjective outcome tests, at 6, 12, 24, 52, and 104 weeks. Tibial and femoral tunnel CSA was measured on each MRI at tunnel aperture (ttA and ftA), midsection (ttM and ftM), and exit (ttE and ftE). Logistic regression modeling was used to examine the predictive value of demographic data and preoperative bone quality (as measured by dual-energy x-ray absorptiometry) on functional outcome scores, manual and instrumented laxity measurements, and changes in tunnel area over time.

Results: Eighteen patients (including 12 men), mean age 35.5 ± 8.7 years, underwent ACL-R. There was significant tunnel expansion at ttA and ftA sites 6 weeks postoperatively (P = .024 and .0045, respectively). Expansion continued for 24 weeks, with progressive tunnel narrowing thereafter. Average ttA CSA was significantly larger than ftA CSA at all times. The ttM significantly expanded after 6 weeks (P = .06); continued expansion to week 12 was followed by 21 months of reduction in tunnel diameter. The ftM and both ttE and ftE sites decreased in CSA over the 2 years. Median Lysholm and International Knee Documentation Committee scores significantly improved at final follow-up (P = .0083 and <.0001, respectively), and patients returned to preoperative activity levels. Pivot shift significantly decreased (P < .0001). Younger age (<30 years), male sex, and delayed ACL-R (>1 year from time of injury) predicted increased tunnel widening and accelerated expansion in CSA (P < .005).

Conclusion: Tunnel expansion after ACL-R occurs early and primarily at the tunnel apertures. Expansion may not affect clinical outcome. Younger age, male sex, and delay from injury to ACL-R may be potential risks for enlargement.

Link to the article


Tunnel communication and increased graft signal intensity on magnetic resonance imaging of double-bundle anterior cruciate ligament reconstruction, Kiekara et al. (2014).
Arthroscopy: The journal of arthroscopic and related surgery 2014; 30 (12): 1595-1601.

Purpose: This study aimed to evaluate the association between magnetic resonance imaging (MRI) findings of tunnel communication and increased graft signal intensity (SI) and clinical evaluation of knee stability and outcome after double-bundle (DB) anterior cruciate ligament (ACL) reconstruction.

Methods: Fifty-nine patients were evaluated with 1.5 T MRI and with clinical evaluation 2 years after DB ACL reconstruction. The MRI finding of tunnel communication was defined as the absence of a bony bridge between the anteromedial (AM) and posterolateral (PL) tunnels. The SI of the intra-articular portion of both grafts was analyzed on proton-density (PD)-weighted and T2-weighted images and graded on a scale, with I being a normal SI similar to that of the posterior cruciate ligament, II being > 50% of the graft having a normal SI, and III being < 50% of the graft having a normal SI. The clinical evaluation of knee stability and function included KT-1,000 arthrometric side-to-side difference, pivot shift test, and International Knee Documentation Committee (IKDC) and Lysholm knee evaluation scores. The association between the MRI findings and the clinical findings was calculated using the Fisher exact test and the 2-tailed t test.

Results: Tunnel communication was seen in the femur in 10% of patients and in the tibia in 27% of patients. Increased graft SI was seen in 15% of the AM grafts and 59% of the PL grafts. No statistically significant association (P < .05) between the MRI findings of tunnel communication or increased graft SI and knee laxity was found.

Conclusions: The MRI findings of tunnel communication or increased graft SI were not associated with knee laxity 2 years after DB ACL reconstruction. Tibial tunnel communication was associated with increased range of movement with flexion, and increased AM graft SI was associated with reduced range of flexion in the knee.

Link to the article


Effect of tunnel placements on clinical and magnetic resonance imaging findings 2 years after anterior cruciate ligament reconstruction using the double-bundle technique, Suomalainen et al. (2014).
Open Access J Sports Med. 2014 Aug 28;5:197-203.

Purpose: The purpose of the study reported here was to find out if the clinical and magnetic resonance imaging (MRI) findings of a reconstructed anterior cruciate ligament (ACL) have an association. Our hypothesis, which was based on the different functions of the ACL bundles, was that the visibility of the anteromedial graft would have an impact on anteroposterior stability, and the visibility of the posterolateral graft on rotational stability of the knee.

Methods: This study is a level II, prospective clinical and MRI study (NCT02000258). The study involved 75 patients. One experienced orthopedic surgeon performed all double-bundle ACL reconstructions. Two independent examiners made the clinical examinations at 2-year follow-up: clinical examination of the knee; KT-1000, International Knee Documentation Committee and Lysholm knee evaluation scores; and International Knee Documentation Committee functional score. The MRI evaluations were made by two musculoskeletal radiologists separately, and the means of these measurements were used.

Results: We found that the location of the graft in the tibia had an impact on the MRI visibility of the graft at 2-year follow-up. There were significantly more partially or totally invisible grafts if the insertion of the graft was more anterior in the tibia. No association was found between the clinical results and the graft locations.

Conclusion: Anterior graft location in the tibia can cause graft invisibility in the MRI 2 years after ACL reconstruction, but this has no effect on the clinical recovery of the patient.

Link to the article


Double-bundle versus single-bundle anterior cruciate ligament reconstruction – a prospective randomized study with 5-year results, Suomalainen et al. (2012).
Am J Sports Med. 2012 Jul;40(7):1511-8.

Background: Surgical technique is essential in anterior cruciate ligament (ACL) reconstruction.

Purpose: This randomized 5-year study tested the hypothesis that double-bundle ACL reconstruction with hamstring autografts and aperture screw fixation has fewer graft ruptures and rates of osteoarthritis (OA) and better stability than single-bundle reconstruction.

Study design: Randomized controlled trial; Level of evidence, 1.

Methods: Ninety patients were randomized: double-bundle ACL reconstruction with bioabsorbable screw fixation (DB group; n = 30), single-bundle ACL reconstruction with bioabsorbable screw fixation (SBB group; n = 30), and single-bundle ACL reconstruction with metallic screw fixation (SBM group; n = 30). The following evaluation methods were used: clinical examination, KT-1000 arthrometer measurement, and International Knee Documentation Committee (IKDC) and Lysholm knee scores. Additionally, radiographic evaluation was made by a musculoskeletal radiologist who was unaware of the patients’ clinical and surgical data. A single orthopaedic surgeon performed all the operations, and clinical follow-up assessments were made in a blinded manner by an independent examiner.

Results: Preoperatively, there were no differences between the groups. Eleven patients (7 in the SBB group, 3 in the SBM group, and 1 in the DB group) had a graft failure during the follow-up and went on to ACL revision surgery (P < .043). Of the remaining 79 patients, a 5-year follow-up was performed for 65 patients (20 in the DB group, 21 in the SBB group, and 24 in the SBM group) who had their grafts intact. At 5 years, there was no statistically significant difference in the pivot-shift or KT-1000 arthrometer tests. In the DB group, 20% of the patients had OA in the medial femorotibial compartment and 10% in the lateral compartment, while the corresponding figures were 33% and 18% in the single-bundle groups, again an insignificant finding. Further, no significant group differences were found in the knee scores.

Conclusion: The double-bundle surgery resulted in significantly fewer graft failures and subsequent revision ACL surgery than the single-bundle surgeries during the 5-year follow-up. Knee stability and OA rates were similar at 5 years. In view of the size of the groups, some caution should be exercised when interpreting the lack of difference in the secondary outcomes.

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Double-bundle anterior cruciate ligament reconstruction using hamstring autografts and bioabsorbable interference screw fixation – a prospective, randomized, clinical study with 2-year results, Järvelä et al. (2008a).
Am J Sports Med. 2008 Feb;36(2):290-7.

Background: Conventional anterior cruciate ligament reconstruction techniques have focused on restoration of the anteromedial bundle only, which, however, may be insufficient in restoring the rotational stability of the knee.

Hypothesis: Rotational stability of the knee is better when using a double-bundle technique instead of a single-bundle technique for anterior cruciate ligament reconstruction.

Study design: Randomized controlled clinical trial; Level of evidence, 1.

Methods: Seventy-seven patients were randomized into 3 different groups for anterior cruciate ligament reconstruction with hamstring tendons: double-bundle with bioabsorbable screw fixation (n = 25), single-bundle with bioabsorbable screw fixation (n = 27), and single-bundle with metallic screw fixation (n = 25). The evaluation methods were clinical examination, KT-1000 arthrometric measurement, and the International Knee Documentation Committee and Lysholm knee scores.

Results: There were no differences between the study groups preoperatively. Seventy-three patients (95%) were available at a minimum 2-year follow-up (range, 24-35 mo). The rotational stability of the knee, as evaluated by the pivot-shift test, was the best in the patients in the double-bundle group. In addition, the patients in the single-bundle groups had more graft failures than those in the double-bundle group. Concerning the anterior stability of the knee as measured with the KT-1000 arthrometer, the group differences were not statistically significant. No significant differences were found between the groups in knee scores.

Conclusion: Rotational stability of the knee is better when using the double-bundle technique instead of the single-bundle technique in anterior cruciate ligament reconstruction.

Link to the article


Book: The anterior cruciate ligament: reconstruction and basic science, Järvelä et al. (2008b).
Chapter: Improving biodegradable interference screw properties by combining polymers


Cranio-Maxillofacial Surgery

Inion CPS™


Examining the Relationship Between Wound Complications and the Use of Resorbable Plates in Cranial Vault Reconstruction, Reilly et al. (2021).
J Craniofac Surg. 2021 Oct 1;32(7):2310-2313.

Background: Resorbable plates are commonly used in cranial vault reconstruction surgery. There are few published papers examining their safety profile. The authors examined the prevalence of wound complications associated with the use of resorbable plates (Inion CPS Fixation System) in pediatric patients undergoing cranial vault reconstruction.

Methods: A retrospective review of patients (n = 182) who underwent cranial vault reconstruction using resorbable plate fixation was undertaken. All procedures were performed by a single Craniofacial Surgeon at the National Pediatric Craniofacial Center from 2008 to 2016. Wound complications were identified from a prospectively maintained database and medical note review. Several key patient characteristics and surgical variables were also recorded and tested for associations with wound complications.

Results: A total of 58.8% (107 of 182) of patients were male with a median age at surgery of 16.2 months. Overall, 12.1% (22 of 182) experienced a postoperative wound complication requiring hospital admission. A total of 2.73% (5 of 182) of the patients that returned to theatre had remnants of plates removed. The authors had a mean time from primary operation to secondary reoperation of 103 days. In univariate statistical analysis, females were more likely to develop a wound complication. However, in stratified analyses excluding patients with an underlying genetic syndrome, increasing age, and lower weight but not gender were associated with wound complications.

Conclusions: A 12.1% (22 of 182) wound complication rate with the use of the Inion CPS Fixation System was observed. Inion plates appear to have an equivalent safety profile to other fixation devices. Increasing age and lower weight were associated with an increased risk of wound complications in nonsyndromic patients.

Link to the article


Delayed Foreign Body Reaction Caused by Bioabsorbable Plates Used for Maxillofacial Fractures, Jeon et al. (2016).
Arch Plast Surg. 2016 Jan;43(1):40-5.

Background: Bioabsorbable plates and screws are commonly used to reduce maxillofacial bones, particularly in pediatric patients because they degrade completely without complications after bone healing. In this study, we encountered eight cases of a delayed foreign body reaction after surgical fixation with bioabsorbable plates and screws.

Methods: A total of 234 patients with a maxillofacial fracture underwent surgical treatment from March 2006 to October 2013, in which rigid fixation was achieved with the Inion CPS (Inion, Tampere, Finland) plating system in 173 patients and Rapidsorb (Synthes, West Chester, PA, USA) in 61 patients. Their mean age was 35.2 years (range, 15-84 years). Most patients were stabilized with two- or three-point fixation at the frontozygomatic suture, infraorbital rim, and anterior wall of the maxilla.

Results: Complications occurred in eight (3.4%) of 234 patients, including palpable, fixed masses in six patients and focal swelling in two patients. The period from surgical fixation to the onset of symptoms was 9-23 months. Six patients with a mass underwent secondary surgery for mass removal. The masses contained fibrous tissue with a yellow, grainy, cloudy fluid and remnants of an incompletely degraded bioabsorbable plate and screws. Their histological findings demonstrated a foreign body reaction.

Conclusions: Inadequate degradation of bioabsorbable plates caused a delayed inflammatory foreign body reaction requiring secondary surgery. Therefore, it is prudent to consider the possibility of delayed complications when using bioabsorbable plates and surgeons must conduct longer and closer follow-up observations.

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Use of biodegradable plates and screws in the treatment of pediatric facial bone fractures, Ali et al. (2016).
Egyptian Journal of Oral & Maxillofacial Surgery 7.3 (2016): 86-93.

Pediatric patients with facial fractures are a unique challenge in terms of their treatment planning, which is different from that of adult patients. Early literature has advocated conservative closed management of pediatric facial fractures to prevent complications. However, recent advances in treatment have enabled us to use biodegradable plates and screws, which overcome the limitations of metallic plates.

This study was conducted to evaluate the effectiveness of Inion CPS biodegradable plates and screws on pediatric facial fractures.

Patients and methods
The study was conducted on 30 pediatric patients with maxillofacial fractures requiring open reduction and internal fixation. Fractures with infection and comminuted fractures were excluded. Patients were aged 3–12 years, 18 boys and 12 girls, with different types of trauma: 12 patients had suffered falls, 12 patients had middle cerebral artery (MCA), four patients had sports-related fracture; and two patients had assault-related fractures. The site of fracture was different: 18 patients had mandibular fractures, four patients had zygomatic complex fractures, four patients had orbital fractures, two patients had maxillary fractures (one isolated and the other with mandibular fracture), and one patient had frontal bone and sinus fractures (anterior wall). Fractures were plated with a biodegradable system (Inion CPS) using standard plating principles. Postoperative complications were assessed.

Satisfactory reduction was obtained in all patients, as judged from the position of the fracture segments in 24-h postoperative radiographs compared with all subsequently obtained images. The undisturbed reduction was considered as a marker of the stable fixation provided by the bioresorbable system. The screw holes visible as radiolucencies on the radiograph were also seen to maintain their position throughout the period of follow-up.

In our study, we concluded that the use of Inion bioresorbable plates is effective in the treatment of facial fracture in pediatric patients. There was no complication and no growth disturbance in the follow-up period, which proves that bioresorbable plates provide stable fixation in children. Our data support the use of bioresorbable plate fixation in pediatric craniofacial surgery as a means of avoiding the potential and well-documented problems associated with rigid metal fixation.

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Management of pediatric mandibular fractures using bioresorbable plating system – Efficacy, stability, and clinical outcomes: Our experiences and literature review, Singh et al. (2016).
J Oral Biol Craniofac Res. 2016 May-Aug;6(2):101-6.

Aims: The purpose of this study was to determine the efficacy and stability of the biodegradable fixation system for treatment of mandible fractures in pediatric patients by measuring the bite force.

Methods: Sixty pediatric patients with mandibular fractures (36 males, 24 females) were included in this study. The 2.5-mm resorbable plates were adapted along Champy’s line of ideal osteosynthesis and secured with four 2.5 mm diameter monocortical resorbable screws, 8 mm in length. All patients were followed for 10 months. Clinical parameters, such as soft tissue infection, nonunion, malunion, implant exposure, malocclusion, nerve injury, and bite force for stability, were prospectively assessed.

Results: Adequate fixation and primary bone healing was achieved in 100% of the cases. Six minor complications (10%) were observed: 2 soft tissue infections (3%), 1 plate dehiscence (2%), 1 malocclusion (2%), and 2 paresthesia (3%).

Conclusion: 2.5-mm resorbable plating system along Champy’s line of ideal osteosynthesis is a good treatment modality for mandible fractures in pediatric patients.

Link to the article


Clinical and radiographic evaluation of biodegradable bone plates in the treatment of mandibular body fractures, Elhalawany et al. (2015).
Niger Med J. 2015 Jan-Feb;56(1):48-53.

Background: Many different systems are available for the treatment of fractures ranging from the heavy compression plates for mandibular reconstruction to low profile plates for mid-facial fixation, and are made either from stainless steel, titanium or vitallium. Recently, biodegradable, self-reinforced polylactide plates and screws have been used for the internal fixation of fractures of the mandible with good results.

Aim of this study: This study evaluated clinically the biodegradable bone plates for treatment of mandibular body fracture and to evaluate bone healing during the follow-up period using digital radiography.

Materials and methods: Eight patients had been suffered from mandibular body fractures were treated using Inion CPS(TM) bioresorbable fixation system and the healing process were followed up using digitised panoramic radiography at first week and after 1, 3 and 6 months.

Results: Clinical examination of fractured segments revealed stable fixation across the fracture sites while visual and quantitative assessment of radiograph showed healing process was comparable with results previously reported by titanium bone plates.

Conclusion: Open reduction and internal fixation of mandibular fractures using bioresorbable fixation system with a brief period of inter-maxillary fixation have evolved to the point where the physical properties are sufficient to withstand the post-operative loads required for fracture repair of mandibular body fractures. The foreign body reaction is a major material-related problem which requires further studies.

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Comparison of the long-term skeletal stability between a biodegradable and a titanium fixation system following BSSO advancement – a cohort study based on a multicenter randomised controlled trial, Van Bakelen et al. (2015).
Br J Oral Maxillofac Surg. 2014 Oct;52(8):721-8.

Biodegradable fixation systems could reduce or eliminate the problems associated with removal of titanium plates. A multicenter randomised controlled trial (RCT) was performed in the Netherlands from December 2006-July 2009, and originally 230 injured and orthognathic patients were included. The patients were randomly assigned to either a titanium control group (KLS Martin) or to a biodegradable test group (Inion CPS). The aim of the present study was to compare the long-term skeletal stability of advancement bilateral sagittal split osteotomies (BSSO) of a biodegradable system and a titanium system. Only patients from the original RCT who were at least 18 years old and who had a BSSO advancement osteotomy were included. Those who had simultaneous Le Fort I osteotomy or genioplasty were excluded. Analysis of skeletal stability was made by digital tracing of lateral cephalograms. Long-term skeletal stability in BSSO advancement did not differ significantly between patients treated with biodegradable plates and screws and those treated with titanium plates and screws. Given the comparable amount of relapse, the general use of Inion CPS in the treatment of BSSO advancement should not be discouraged. On the basis of other properties a total picture of the clinical use can be obtained; the short-term stability, the intraoperative switches, the number of plates removed and cost-effectiveness. Trial registration of original RCT:; ISRCTN 44212338.

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Comparison of resorbable plates and titanium plates for fixation stability of combined mandibular symphysis and angle fractures, Lim et al. (2014).
J Korean Assoc Oral Maxillofac Surg. 2014 Dec;40(6):285-90.

Objectives: We compared resorbable plates with titanium plates for treatment of combined mandibular angle and symphyseal fractures.

Materials and methods: Patients with mandibular angle and symphysis fractures were divided into two groups. The control (T) group received titanium plates while the experimental (R) group received resorbable plates. All procedures were carried out under general anesthesia using standard surgical techniques. We compared the frequency of wound dehiscence, development of infection, malocclusion, malunion, screw breakage, and any other technical difficulties between the two groups.

Results: Thirteen patients were included in the R group, where 39 resorbable plates were applied. The T group consisted of 16 patients who received 48 titanium plates. The mean age in the R and T groups was 28.29 and 24.23 years, respectively. Primary healing of the fractured mandible was obtained in all patients in both groups. Postoperative complications were minor and transient. Moreover, there were no significant differences in the rates of various complications between the two groups. Breakage of 3 screws during the perioperative period was seen in the R group, while no screws or plates were broken in the T group.

Conclusion: Resorbable plates can be used to stabilize combined mandibular angle and symphysis fractures.

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Can resorbable screws effectively be used in fixating bilateral sagittal split osteotomies for mandibular advancement? A randomized controlled trial, Yu et al. (2014).
J Oral Maxillofac Surg. 2014 Nov;72(11):2273-7.

Purpose: Resorbable fixation material is an attractive option for those patients undergoing orthognathic surgery. The efficacy of resorbable screws was tested in bilateral mandibular sagittal split osteotomies (BSSOs) performed for correction of retrognathic mandibles.

Materials and methods: One hundred one patients were enrolled in this prospective randomized clinical trial. Patients in group 1 (n = 51) received titanium screws (Stryker) and patients in group 2 (n = 50) received resorbable screws (Inion CPS). Outcome measurements were compared for statistical significance.

Results: There was a statistically significant difference in the use of postoperative elastics (P < .0001). There was no statistically significant difference in other outcome measurements, including clinical evidence of relapse.

Conclusion: Resorbable screws can be used effectively for fixation of BSSO for mandibular advancement. A higher incidence of rotation around positional screws can result secondary to the mechanical “looseness” when using resorbable screws. This can be treated effectively using Class III mechanic elastics during the initial stages of bone healing.

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3D vector analysis of mandibular condyle stability in mandibular setback surgery with bicortical bioabsorbable screw fixation, Lee et al. (2014).
J Craniomaxillofac Surg. 2014 Jul;42(5):e105-10.

Introduction: Bioabsorbable screws became widely used for stable fixation in orthognathic surgery as biomechanical technology advanced. Recently, 3D image analyses begin to be used to evaluate surgical changes. The purpose of this study was to evaluate, using 3D vector analysis, the stability of bicortical bioabsorbable screw fixation in mandibular setback using a sagittal split ramus osteotomy. Spatial change of the mandibular condyle was determined by 3D coordinates containing directional information.

Materials and methods: Bicortical screw fixation was performed using either a bioabsorbable screw (25 patients) or a titanium screw (5 patients) in orthognathic surgery. Pre- and post-operative CT images (6 months after surgery) were superimposed digitally. A 3D coordinate (X, Y, Z) and vectors were employed to quantify spatial changes of the condyle and analysed statistically.

Results: Measuring on 3D image showed stable error about 0.16 mm. There were no significant differences in the total spatial changes of the condyle between titanium and bioabsorbable screws with the exception of the lateral-medial direction of the condylar centre (P = 0.042). The directional vector components were stable, regardless of mandibular setback.

Conclusion: In 3D vector analysis, bioabsorbable screw fixation in SSRO with distal segment osteotomy shows clinically acceptable postoperative condylar position stability.

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Skeletal stability of bioresorbable fixation in orthognathic surgery: a systemic review, Yang et al. (2014).
J Craniomaxillofac Surg. 2014 Jul;42(5):e176-81.

Background: Over the past 20 years, there has been an increase in the use of bioresorbable fixation system in orthognathic surgery, but concerns remain about the stability of fixation. This review is to seek evidence for the effectiveness of bioresorbable fixation systems compared to titanium systems used for orthognathic surgery.

Methods: A systematic review of the scientific literature listed on PubMed, Embase, Cochrane Central Register of Systemic Reviews and Cochrane Central Register of Controlled Trials was performed, up to December 2012.

Results: Twenty articles were selected based on inclusion and exclusion criteria: five RCTs and fifteen prospective. We compared these studies, published between 1997 and 2012 and involving 1092 participants examining skeletal stability of bioresorbable fixation in orthognathic surgery.

Conclusion: This review found that the published data have shown that bioresorbable fixation systems produce reliable skeletal stability.

Link to the article


The “in situ molding technique: ” an accurate and simple way to fix resorbable plates to the facial skeleton, Sadigh et al. (2014).
J Craniofac Surg. 2014 Sep;25(5):1766-8.

Bioabsorbable plates developed for use in the facial skeleton have become an integral part of the craniomaxillofacial surgeon’s reconstructive armamentarium. They avoid the problems associated with the retention of metal plates and can be easily contoured when heated in a thermobath. The technical process of molding and securing these devices, often through small access incisions, to achieve rigid fixation of facial fractures can be difficult. In this article, we describe a simple, novel technique that we have developed, using hot water suction irrigation, to achieve in situ molding of resorbable plates during facial fracture fixation. We used this technique to fix 123 facial fractures in 110 patients over a 4-year period. No complications secondary to the use of hot water suction irrigation were encountered.

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Are bioresorbable polylactate devices comparable to titanium devices for stabilizing Le Fort I advancement?, Blakey et al. (2014).
Int J Oral Maxillofac Surg. 2014 Apr;43(4):437-44.

The purpose of this study was to evaluate whether skeletal and dental outcomes following Le Fort I surgery differed when stabilization was performed with polylactate bioresorbable devices or titanium devices. Fifty-seven patients with preoperative records and at least 1 year postoperative records were identified and grouped according to the stabilization method. All cephalometric X-rays were traced and digitized by a single operator. Analysis of covariance was used to compare the postsurgical change between the two stabilization methods. Twenty-seven patients received bioresorbable devices (group R), while 30 received titanium devices (group M). There were no statistically significant differences between the two groups with respect to gender, race/ethnicity, age, or dental and skeletal movements during surgery. Subtle postsurgical differences were noted, but were not statistically significant. Stabilization of Le Fort I advancement with polylactate bioresorbable and titanium devices produced similar clinical outcomes at 1 year following surgery.

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To evaluate the efficacy of biodegradable plating system for fixation of maxillofacial fractures: A prospective study, Bali et al. (2013).
Natl J Maxillofac Surg. 2013 Jul;4(2):167-72.

Aims: The present study was undertaken to evaluate the efficacy of biodegradable plating system for fixation of maxillofacial fractures and to study the morbidity associated with the use of biodegradable plates and screws.

Materials and methods: This prospective study consisted of 10 patients with maxillofacial fractures requiring open reduction and internal fixation. Fractures with infection, comminuted and pathological fractures were excluded. All were plated with biodegradable system (Inion CPS) using standard plating principles and observed for a total period of 24 weeks. Characteristics of the fractures, ease of use of bioresorbable plate/screw system and post operative complications were assessed.

Results: Of total 10 patients, eight patients were of midface fracture and two pediatric patients with mandibular fracture, with nine male and one female. The mean age was 32.8 years. Out of 20 plates and 68 screws applied to the 10 fractures sites; there were three incidences of screw breakage with no other intraoperative difficulties. Paresthesia of the infraorbital nerve was present in two patients, and recovered completely in four weeks after surgery. Fracture reduction was considered to be satisfactory in all cases. One patient developed postsurgical infection and was managed with oral antibiotics and analgesics.

Conclusions: Favorable healing can be observed through the use of biodegradable plates and screws to stabilize selected midface fractures in patients of all ages, as well as mandible fractures in early childhood, however further studies with more sample size are required.

Link to the article


Treatment of mandible fractures using resorbable plates with a mean of 3 weeks maxillomandibular fixation: a prospective study, Vázquez-Morales et al. (2013).
Oral Surg Oral Med Oral Pathol Oral Radiol. 2013 Jan;115(1):25-8.

Purpose: In this study, a 2.5-mm resorbable plating system (Inion CPS, Tampere Finland) was assessed for the fixation of mandibular fractures with 3 weeks of maxillomandibular fixation.

Patients and methods: Fifty mandibular fractures in 34 patients (32 males, 2 females) with a mean of 20.8 days of maxillomandibular fixation (MMF) were included in this study. The 2.5-mm resorbable plates were adapted along Champy’s line of ideal osteosynthesis and secured with four 8 × 2.5 mm monocortical resorbable screws. All patients were followed for a minimum of 6 weeks with an average long-term follow-up of 10 months. The incidence of soft tissue infection, nonunion, malunion, malocclusion, osteomyelitis, nerve injury, and tooth damage was prospectively assessed.

Results: Primary bone healing was achieved in 100% of cases. Ten minor complications (20%) were observed: 5 soft tissue infections (10%), 4 plate dehiscences (8%), and 1 malocclusion (2%). No evidence of malunion, nonunion, osteomyelitis, plate fracture, or iatrogenic dental or nerve injury was noted; no readmission or reoperation was necessary.

Conclusion: The Inion 2.5-mm resorbable plating system along Champy’s line of ideal osteosynthesis plus 3 weeks of MMF is a viable option for the treatment of mandible fractures.

Link to the article


Can resorbable screws effectively be used in fixating bilateral sagittal split osteotomies for mandibular advancement? A randomized controlled trial, Yu and Bloomquist (2013).
J Oral Maxillofac Surg. 2014 Nov;72(11):2273-7.

Purpose: Resorbable fixation material is an attractive option for those patients undergoing orthognathic surgery. The efficacy of resorbable screws was tested in bilateral mandibular sagittal split osteotomies (BSSOs) performed for correction of retrognathic mandibles.

Materials and methods: One hundred one patients were enrolled in this prospective randomized clinical trial. Patients in group 1 (n = 51) received titanium screws (Stryker) and patients in group 2 (n = 50) received resorbable screws (Inion CPS). Outcome measurements were compared for statistical significance.

Results: There was a statistically significant difference in the use of postoperative elastics (P < .0001). There was no statistically significant difference in other outcome measurements, including clinical evidence of relapse.

Conclusion: Resorbable screws can be used effectively for fixation of BSSO for mandibular advancement. A higher incidence of rotation around positional screws can result secondary to the mechanical “looseness” when using resorbable screws. This can be treated effectively using Class III mechanic elastics during the initial stages of bone healing.

Link to the article


Two-Year Follow-up on the Use of Absorbable Mesh Plates in the Treatment of Medial Orbital Wall Fractures, You et al. (2013).
Arch Plast Surg. 2013 Nov;40(6):728-34.

Background: Absorbable materials offer many advantages in the reconstruction of orbital walls; however, the possibility of postoperative enophthalmos after complete absorption cannot be excluded. We evaluated the postoperative results of absorbable mesh plates used as onlay implanting on the medial orbital wall to determine whether they are suitable for medial orbital wall reconstruction.

Methods: The study included 20 patients with medial orbital wall fractures who were followed up for more than 2 years postoperatively. We used absorbable mesh plates in all of the patients. We measured the following: the changes in the expanded orbital volume by comparing the preoperative and postoperative computed tomography (CT) scans and the degree of clinical enophthalmos.

Results: There were no major complications associated with the use of absorbable materials such as infection, migration, or extrusion of mesh plates during the long-term follow-up. The orbital volumetric changes between the preoperative and postoperative CT scans were not statistically significant. However, the expanded orbital volume was not related to the degree of clinical enophthalmos.

Conclusions: The reconstructed orbital wall may provide supportive scar tissue to the orbital contents even after the absorbable materials have dissolved completely. Absorbable mesh plates could be another option for the reconstruction of the medial orbital wall.

Link to the article


Evaluation of the Fatigue Performance and Degradability of Resorbable PLDLLA-TMC Osteofixations, Landes et al. (2013).
Open Biomed Eng J. 2013 Nov 29;7:133-46.

The fatigue performance of explanted in-situ degraded osteofixations/osteosyntheses, fabricated from poly (70L-lactide-co-24DL-lactide-6-trimethylane-carbonate or PLDLLA-TMC) copolymer was compared to that of virgin products. The fatigue test was performed on 21 explants retrieved from 12 women and 6 men; 16-46 years by a custom-designed three-point bend apparatus using a staircase method and a specified failure criterion (an increase of the deflection of the specimen > 1 mm) with run-out designated as “no failure” after 150,000 loading cycles. While all the virgin products showed run-out at 38N, all of the specimens fabricated from explants failed at this load level. For the explant specimens, although there was a trend of decreased failure load with increased in-situ time, this decrease was pronounced after 4 months in-situ, however, not yet statistically significant, while a 6-month in-situ explant had significantly less failure load. Three and four month in-situ explants had highly significant differences in failure load between measurements close and distant to the osteotomy line: p=0.0017 (the region of maximum load in-situ). In the virgin products, there were only traces of melt joining and cooling, left from a stage in the manufacturing process. For the implants retrieved after 4.5 months in-situ, the fracture surfaces showed signs of degradation of the implants, possibly caused by hydrolysis, and for those retrieved after 9 months in-situ, there were cracks and pores. Thus, the morphological results are consistent with those obtained in the fatigue test. The present results suggest that resorbable osteofixations fabricated from PLDLLA-TMC are stable enough to allow loading of the healing bone and degrade reliably.

Link to the article


Fixation of zygomatic and mandibular fractures with biodegradable plates, Degala et al. (2013).
Ann Maxillofac Surg. 2013 Jan;3(1):25-30.

Context: In this prospective study, 13 randomly selected patients underwent treatment for zygomatic-complex fractures (2 site fractures) and mandibular fractures using 1.5 / 2 / 2.5-mm INION CPS biodegradable plates and screws.

Aims: To assess the fixation of zygomatic-complex and mandibular fractures with biodegradable copolymer osteosynthesis system.

Materials and methods: In randomly selected 13 patients, zygomatic-complex and mandibular fractures were plated using resorbable plates and screws using Champy’s principle. All the cases were evaluated clinically and radiologically for the type of fracture, need for the intermaxillary fixation (IMF) and its duration, duration of surgery, fixation at operation, state of reduction at operation, state of bone union after operation, anatomic reduction, paresthesia, occlusal discrepancies, soft tissue infection, immediate and late inflammatory reactions related to biodegradation process, and any need for the removal of the plates.

Statistical analysis used: Descriptives, Frequencies, and Chi-square test were used.

Results: In our study, the age group range was 5 to 55 years. Road traffic accidents accounted for the majority of patients six, (46.2%). Postoperative occlusal discrepancies were found in seven patients as mild to moderate, which resolved with IMF for 1-8 weeks. There were minimal complications seen and only as soft tissue infection.

Conclusions: Use of biodegradable osteosynthesis system is a reliable alternative method for the fixation of zygomatic-complex and mandibular fractures. The biodegradable system still needs to be refined in material quality and handling to match the stability achieved with metal system. Biodegradable plates and screws is an ideal system for pediatric fractures with favorable outcome.

Link to the article


Bio-resorbable plates as effective implant in paediatric mandibular fracture, Singh et al. (2012).
J Maxillofac Oral Surg. 2012 Dec;11(4):400-6.

Aim: To evaluate the efficacy of bio-resorbable plates in paediatric mandibular fracture.

Materials and methods: In the present study, 40 cases of mandibular fractures were treated by Inion Cps plating system using, 2 and 2.5 mm (LPLA/DLPLA/TMC/PGA) bio-resorbable bone plates and screws of 6 and 8 mm screws. The assessment of the patients was done at 2 week, 1, 3, and 6 months using the clinical parameters and bite force recording.

Results: There was significant reduction in pain at different follow-ups. Paraesthesia was found in two patients with body fracture which remained for 2 week and 1 month follow-up. No paraesthesia was found after 3rd follow-up. Significant stability of fracture fragments were found on different follow ups. Implant exposure was present only in two patients (5%) at 1 month follow up. There was significant increase in incisor, right molar and left molar bite force at 1, 3 and 6 months, from 2nd week onwards.

Conclusion: These findings show that the use of bio-resorbable plates in paediatric mandibular fracture was efficacious enough to bear the masticatory loads during osteosynthesis of the fracture. The recent and significant achievement is the advent of bio-resorbable osteosynthesis devices that has almost solved the problems of stress shielding, secondary surgery and corrosion when metal implants are left-in situ.

Link to the article


Comparative study of skeletal stability between bicortical resorbable and titanium screw fixation after sagittal split ramus osteotomy for mandibular prognathism, Paeng et al. (2012).
J Craniomaxillofac Surg. 2012 Dec;40(8):660-4.

Introduction: Resorbable screw fixation for orthognathic surgery is widely used in oral and maxillofacial surgery and has several advantages. However, surgeons are concerned about using resorbable screws in orthognathic surgery because of possible postoperative complications such as relapse, screw fracture, and infection. The purpose of this study was to evaluate the skeletal stability of bicortical resorbable screw fixation after sagittal split ramus osteotomies for mandibular prognathism.

Materials and methods: This study included 25 patients who underwent mandibular setback surgery fixed with resorbable screws after sagittal split osteotomy at the Department of Oral and Maxillofacial Surgery at Seoul National University Dental Hospital. Five resorbable screws (Inion CPS(®), Inion Ltd., Finland) were applied bicortically at each osteotomy site via a transbuccal approach. No rigid intermaxillary fixation was applied on the first postoperative day. Passive mouth opening exercises were allowed, using two light, rubber elastics for guidance. The control group was 25 patients fixed with four titanium screws. The follow-up period was 12-22 months (mean 17.8 months). Postoperative skeletal changes on lateral cephalometric radiographs were analyzed and compared between the two groups preoperatively, immediately postoperatively, and 6 months postoperatively.

Results: The average setback was 6.9 mm and no major intraoperative complications occurred. One patient experienced infection immediately after surgery that was controlled uneventfully. The data did not demonstrate any significant difference in postoperative skeletal stability between the two groups. Differences between the immediate postoperative state and 6 months after surgery were not significant. In earlier cases, especially for patients with severe mandibular prognathism, immediate postoperative elastic traction was needed for stable occlusal guidance.

Conclusions: The results of this study indicate that bicortical resorbable screws offer a clinically stable outcome for the fixation of mandibular sagittal split osteotomies in mandibular prognathism. However the resorbable screws showed less stable results vertically than the titanium screws.

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Treatment of frontal sinus fracture using bioabsorbable mesh plates, Kim et al. (2012).
J Craniofac Surg. 2012 Mar;23(2):549-51.

Accurate reduction and stable fixation are important in the treatment of frontal sinus fracture. Usually, metal plates and screws were used because of easy handling and delicate fixation. However, palpability and possibility for secondary operation for plate removal were shortcomings. For improving these problems, we used absorbable mesh plate for fixation of reduced frontal bones.In this study, 14 patients with frontal sinus fracture were treated by open reduction and rigid fixation using absorbable mesh plates. Mean follow-up period was 17.6 months. Considering anterior and posterior table involvement, nasofrontal duct injury, and concomitant neurosurgical problems, additional surgical procedures including degloving sinus mucosa, cranialization, and obliteration of nasofrontal duct were also conducted.There was no remarkable early and late postoperative complication. Aesthetic results were also satisfactory. Absorbable mesh plates were easy to mold and convenient for screw fixation. Moreover, there was no necessity of secondary operation for removal of plates.We believe that absorbable mesh plates might be a useful material for fixation instead of metal plates and screws especially in mild to moderate degree of frontal bone fractures.

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Effect of number and geometry of resorbable screws on biomechanical stability of in vitro model with sagittal split ramus osteotomy, Hwang et al. (2012).
J Craniofac Surg. 2012 Mar;23(2):363-6.

The purpose of this study was to investigate the effect of the number and the geometry of resorbable screws (RSs; Inion CPS System; Inion Ltd, Tampere, Finland) on the biomechanical stability of the in vitro model with sagittal split ramus osteotomy. The sagittal split ramus osteotomy polyurethane hemimandible (Synbone, Malans, Switzerland) was fixed by 7 osteosynthesis methods after 5 mm advancement of the distal segment (n = 5 for each method): 1TP (1 titanium miniplate and 4 screws), 3RL (3 RSs with linear configuration at the retromolar area [RMA]), 2R1B (2 RSs at RMA and 1 RS at the mandibular body [MB]), 2R1A (2 RSs at the RMA and 1 RS at the mandibular angle [MA]), 3R1B (3 RSs at RMA and 1 RS at the MB), 3R1A (3 RSs at RMA and 1 RS at the MA), and 3R1A1B (3 RSs at the RMA, 1 RS at the MA, and 1 RS at the MB). Values of linear compressive load were measured at 1- to 5-mm displacement of the lower first molar with a 1-mm interval and were statistically analyzed. From 1- to 5-mm displacement, there were significant differences in load values among groups (P < 0.05, P < 0.01, P < 0.01, P < 0.001, and P < 0.001, respectively). When the amount of displacement was increased, the difference in load values between 1TP, 3RL, and 2R1B became significantly prominent. There was a significant difference in total load values according to number and geometry of RSs (P < 0.001). All kinds of geometry with more than 3 RSs were more rigid than 1TP. The 3R1A1B method showed better biomechanical stability than 1TP, 3RL, and 2R1B. In 3 RS and 4 RS groups, fixation in MA (2R1A, 3R1A) exhibited a tendency of better stability than fixation in MB (2R1B, 3R1B). Fixation with 2R1A could provide better biomechanical stability than 1TP and similar rigidity with 3R1A1B.

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Comparative study of bone repair in mandibular body osteotomy between metallic and absorbable 2.0 mm internal fixation systems. Histological and histometric analysis in dogs: a pilot study, Sverzut et al. (2012).
Int J Oral Maxillofac Surg. 2012 Nov;41(11):1361-8.

The objective of this study was to compare the bone repair along a mandibular body osteotomy stabilized with 2.0 mm absorbable and metallic systems. 12 male, adult mongrel dogs were divided into two groups (metallic and absorbable) and subjected to unilateral osteotomy between the mandibular third and fourth premolars, which was stabilized by applying two 4-hole plates. At 2 and 18 weeks, three dogs from each group were killed and the osteotomy sites were removed and divided equally into three parts: the upper part was labelled the tension third (TT), the lower part the compression third (CT), and the part between the TT and CT the intermediary third (IT). Regardless of the treatment system, union between the fragments was observed at 18 weeks and the CT showed more advanced stages of bone repair than the TT. Histometric analysis did not reveal any significant differences among the 3 parts or systems in the distance between bone fragments at 2 weeks. Although at 18 weeks the proportions of newly formed bone did not differ among TT, IT and CT, significantly enhanced bone formation was observed in all sections for the metallic group. The patterns of repair were distinct between treatments.

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Segmental stability of resorbable P(L/DL)LA-TMC osteosynthesis versus titanium miniplates in orthognatic surgery, Ballon et al. (2012).
J Craniomaxillofac Surg. 2012 Dec;40(8):e408-14.

After two decades of the use of resorbable miniplates, new polymer compositions for resorbable osteosynthesis are still being developed to make the handling and outcome of operations even more predictable and give higher stability to the repositioned segments. This study investigates a new resorbable osteosynthesis system in orthognathic patients. 50 patients were treated with P(L/DL)LA-TMC resorbable osteosynthesis and compared to a group of 50 patients treated with titanium miniplates. Segmental stability and relapse were measured comparing preoperative, postoperative and follow-up lateral cephalograms. Throughout this study, resorbables appeared to be as stable as titanium miniplates except in maxillary elongation and mandibular setback. Here, the titanium miniplates showed significantly higher stability than resorbable plates. P(L/DL)LA-TMC osteosynthesis seem to have less strength against compressive forces after maxillary elongation and they are less resistant to the forces the tongue exerts, pressing against the mandible after setback. It can therefore be concluded that the resorbable osteosynthesis can be used in the same situations as titanium miniplates except in maxillary elongation and mandibular setback.

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Patients’ preoperative expectations and postoperative satisfaction of dysgnathic patients operated on with resorbable osteosyntheses, Ballon et al. (2011).
J Craniofac Surg. 2011 Mar;22(2):730-4.

Background: This study evaluated whether personal expectations and satisfaction throughout orthognathic surgery were fulfilled. In addition, patients were interrogated about their experience of resorbable osteosynthesis.

Methods: A total of 50 patients were interviewed 3 times each throughout the study by a mixed questionnaire of standard psychologic tests and a tailored itemized questionnaire regarding their expectations regarding resorbable osteofixation and their postoperative satisfaction.

Results: A postoperative increase in self-esteem and approach to life were evident. An examination of Oral Health-Related Quality of Life showed constant quality of life; an examination of Oral Health Impact Profile-Germany) showed no postoperative difficulties in dental hygiene and nutrition. No statistically significant change in any of the tests could be expressly determined. Avoidance of secondary surgery motivated 94% to choose resorbable osteofixations, although a mere 66% had heard of them before; 90% of patients were satisfied with the operation result.

Conclusions: Orthognathic surgery cannot change preexistent depression or a problematic social background. Mastication and oral health improved, and postoperative happiness and confidence increased. When given the choice between resorbable fixation and titanium osteofixation, patients generally preferred resorbable fixations.

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Poster 49: Assessment of Biomechanical Stability, Stress Distribution and Resorption Patterns of Biodegradable 2.0mm Inion® CPS Fixation System in a Rabbit Model, Atali et al. (2011).
J Oral Maxillofac Surg 2011; 69(9).

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Poster 66: Evaluation of the Inion Resorbable Plating System for Open Reduction Internal Fixation (ORIF) of Mandible Fractures, Rock et al. (2011).
J Oral Maxillofac Surg 2011;69(9).

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The perilobule approach to subcondylar fractures, Baek et al. (2011).
Ann Plast Surg. 2011 Mar;66(3):253-6.

Several approaches to the management of subcondylar fractures have been used, including the submandibular approach, the preauricular approach, and the retromandibular approach. Although they provide excellent access to repair fractures of body, ramus, and condyle, we have found it difficult to manage subcondylar fractures using either of these approaches. We describe a novel approach for subcondylar fractures that provides direct access to the fracture site. A total of 17 consecutive patients underwent open reduction and internal fixation of their subcondylar fractures using this technique. The incision line is located just anterior and posterior to the ear lobe, and is comprised of lower part preauricular and upper retroauricular incisions. Intraoperatively, the method applied shortened the time necessary for and simplified the procedure of reduction and osteosynthesis. The postoperative course was uneventful in most patients. Radiologic follow-up revealed correct reduction and fixation in all the cases. There were no occlusal disturbances, no trismus, no lateral deviations of the mandible, and no nerve lesions. Our findings indicate that the short perilobe approach is an easy and safe technique for displaced subcondylar fractures.

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Biodegradable fixation for craniomaxillofacial surgery: a 10-year experience involving 761 operations and 745 patients, Turvey et al. (2011).
Int J Oral Maxillofac Surg. 2011 Mar;40(3):244-9.

Patient acceptance, safety, and efficacy of poly-l/dl-lactic acid (PLLDL) bone plates and screws in craniomaxillofacial surgery are reported in this article. Included in the sample are 745 patients who underwent 761 separate operations, including more than 1400 surgical procedures (orthognathic surgery (685), bone graft reconstruction (37), trauma (191) and transcranial surgery (20)). The success (no breakage or inflammation requiring additional operating room treatment) was 94%. Failure occurred because of breakage (14) or exuberant inflammation (31). All breakage occurred at mandibular sites and the majority of inflammatory failure occurred in the maxilla or orbit (29), with only two in the mandible. Failures were evenly distributed between the two major vendors. PLLDL 70/30 bone plates and screws may be used successfully in a variety of craniomaxillofacial surgical applications. The advantages include the gradual transference of physiological forces to the healing bone, the reduced need for a second operation to remove the material and its potential to serve as a vehicle to deliver bone-healing proteins to fracture/osteotomy sites. Bone healing was noted at all sites, even where exuberant inflammation required a second surgical intervention.

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Evaluating the applicability of a biodegradable osteosynthesis plating system in the management of zygomatico-maxillary complex fractures, Singh et al. (2011).
Otolaryngol Head Neck Surg. 2011 Dec;145(6):924-9.

Objective: The present study was undertaken to evaluate and analyze the efficacy of bioresorbable plates and screws in internal fixation of zygomatico-maxillary complex (ZMC) fractures and to evaluate the incidence of complications associated with the procedure.

Study design: Case series with planned data collection.

Setting: Pt BD Sharma University of Health Sciences.

Subject and methods: A total of 14 patients with isolated ZMC fractures were included, and exclusion of grossly comminuted, pathological, and infected fractures was done. Open reduction internal fixation was done with biodegradable plates and screws. All patients were reviewed clinically and radiographically at regular follow-up. Occlusion, stability of fracture segments, anesthesia or paresthesia of the infraorbital nerve region, and various complications were assessed periodically.

Results: Fourteen patients with 34 fracture sites were included in the study. Intraoperatively, there were 2 incidences of screw head fracture. As observed clinically, there was complete stability of fracture segments, and no maxillomandibular fixation was required postoperatively. Paresthesia of the infraorbital nerve was present in 5 patients, but the sensation recovered completely in the first 3 months after surgery. The mean pain score was 3 on a visual analogue scale. In 1 case, ectropion developed, and dehiscence occurred in another patient in the early postoperative period. Postoperative radiographs were evaluated for the accuracy of fracture reduction and stability of fixation.

Conclusion: The biodegradable osteosynthesis system exhibits adequate strength and has negligible complications. This system is technique sensitive with satisfactory results in the management of mild to moderately displaced ZMC fractures.

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Fractured facial bone reduction and resorbable plate fixation using tapper, Kim and Kim (2011).
J Craniofac Surg. 2011 Jul;22(4):1215-8.

A resorbable fixation system has many advantages, but there are complicated procedures to be accomplished to fix a resorbable plate. The complicated procedures in the fixation of a resorbable plate make the operation for facial fractures more difficult and can result in extended operation time and incomplete reduction or fixation. For these reasons, we suggest a new way of using a tapper that can make the surgery more simple and accurate than before. After the resorbable plate is properly located above the fractured site, a hole on the fracture fragment is made by drill, and the tapper is inserted into the hole. When the tapper is inserted at the proper depth, the fracture fragment can be reduced to right place by handling the inserted tapper. Then, the tapper is inserted to the end, and the handle is split. While the inserted tapper acting as a temporary metal screw is placed, another hole is made at nearby site and the screw is inserted. Next, the inserted tapper acting as a temporary metal screw is removed, and another screw is inserted into the hole from which the tapper was removed. From October 2006 to April 2008, we applied this procedure to 106 facial bone fractures in 68 patients, and no major complications were noted. In conclusion, we tried to make the operation more simple and accurate by using the tapper as an instrument for reduction and fixation of fracture fragment.

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Equivalence randomized controlled trial of bioresorbable versus titanium miniplates in treatment of mandibular fracture: a pilot study, Bhatt et al. (2010).
J Oral Maxillofac Surg. 2010 Aug;68(8):1842-8.

Purpose: The present study was undertaken to test bioresorbable fixation versus titanium for equivalence in terms of clinical union and complications using the American Association of Oral and Maxillofacial Surgeons parameters of care. The study design was a randomized, controlled, equivalence trial.

Materials and methods: A total of 40 patients were enrolled and allocated to the titanium group and bioresorbable group using a computerized randomization table. All were plated using standard plating principles. In the bioresorbable group, 2 weeks of maxillomandibular fixation was also used. Evaluation of the study endpoint was done at 8 weeks postoperatively. For statistical analysis, the upper limit of the 95% confidence interval was calculated for failure to achieve the primary outcome variable and compared with the maximal clinically acceptable difference between the standard and test modalities in the failure to achieve clinical union (delta). Delta was predetermined as 2%. The other complications were tested for significance using Fisher’s exact test.

Results: Of the 40 patients, 21 were in the titanium group and 19 were in the bioresorbable group, with 20 men and 1 woman in the titanium group and 18 men and 1 woman in the bioresorbable group. The mean age was 28.7 years in the titanium group and 26.6 years in the bioresorbable group. In the titanium group, the complications noted were nonunion in 0%, malocclusion in 7.7%, continued postoperative swelling in 0%, chronic pain in 2%, infection in 5.2%, an inability to chew hard food after 8 weeks in 7.7%, the need for alternative treatment in 0%, and the need for reoperation in 31%. In the bioresorbable group, the complications were nonunion in 4.17%, malocclusion in 11.1%, swelling in 8.3%, chronic pain in 37.5%, infection in 0%, an inability to chew hard food in 11.1%, the need for alternative treatment in 11.1%, and need for reoperation for plate removal in 0%.

Conclusions: The small sample size did not allow any meaningful conclusion to be drawn from the present study in terms of the primary question of achieving union. Both groups matched in outcomes when evaluated only on a clinical basis. The avoidance of repeat surgery for plate removal is a definite advantage of using resorbable plates. However, the results are inconclusive in favor of any particular plating system.

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Treatment of mandibular angle fractures using a single bioresorbable miniplate, Bayat et al. (2010).
J Oral Maxillofac Surg. 2010 Jul;68(7):1573-7.

Purpose: This study evaluated the treatment of mandibular angle fractures via a single biodegradable plate and addressed complications such as malocclusion, infection, soft tissue dehiscence, and nonunion in these patients.

Patients and methods: This prospective study consisted of 19 fractures in 19 patients (18 males and 1 female) with unilateral fractures of the mandibular angle treated by open reduction and rigid internal fixation using 1 biodegradable plate through an intraoral incision. The resorbable plates and screws used consisted of an amorphous injection molded copolymer of L-lactide/D-lactide/trimethylene carbonate (Inion CPS System, Tampere, Finland). Light elastic traction was placed for 14 days postoperatively and patients were followed after operation at 1, 4, 8, and 24 weeks. Panoramic and posteroanterior views of the mandible were taken for evaluation of union.

Results: Clinical and radiographic evaluation indicated union of all fractures after 24 weeks. Three of the patients (15.7%) treated with single biodegradable plate experienced some complications. All the complications were minor and treated in the office. Two patients with infection were treated with oral antibiotic administration without plate removal. One patient with mild malocclusion was treated with elastic traction. There were no cases of nonunion or dehiscence.

Conclusion: Based on this limited series of patients, the use of a single biodegradable plate for unilateral mandibular angle fractures is a reliable fixation technique with minor complications.

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A use of poly-L-lactide, D-lactide sheet on posterior orbital floor fracture, Hwang et al. (2010).
J Craniofac Surg. 2010 Jul;21(4):1221-3.

We present the cases of orbital posterior wall fractures that were fixed with poly-l-lactide, D-lactide (PLDLA) sheets. Poly-L-lactide, D-lactide sheet (0.5-mm thickness) was shaped exactly to fit to the area of orbital floor, and then an extended 1 cm was bent across on the infraorbital rim. That part was fixed with 2 absorbable screws to prevent the sheet from crumpling. Orbital floor fractures of 6 patients (3 posterior-one-half defects and 3 posterior-two-thirds defects) were repaired using PLDLA sheets. Diplopia in 5 patients before surgery was improved, usually within 6 months postoperatively. Clinical enophthalmos was not appreciated in any patient. However, preoperative exophthalmometry measured -1.3 +/- 0.3 mm and postoperatively -0.4 +/- 0.2 mm, respectively. Poly-l-lactide, d-lactide sheet is applicable to safely repair the orbital posterior floor fracture.

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Comparison of the supporting strength of a poly-L-lactic acid sheet and porous polyethylene (Medpor) for the reconstruction of orbital floor fractures, Hwang and Kim (2010).
J Craniofac Surg. 2010 May;21(3):847-53.

The aim of this study was to elucidate the supporting strength of the curved poly-L-lactic acid (PLLA) sheet and porous polyethylene (Medpor) for reconstruction of orbital floor fractures. For one-half and two-thirds orbital floor fractures, reconstruction was performed using the PLLA sheet and Medpor. The PLLA sheet was molded to fit the orbital floor (concavity). The anterior portion (1 cm) was curved to fit the inferior orbital rim and fixed with a screw. Medpor was designed to fit the orbital floor. A screw was fixed 6 mm away from the anterior border of the orbital floor. Each implant was hung by wire, and the degree of sagging of the implant was measured using micrometers by the power of a force gauge. For one-half orbital floor fractures, the power of the PLLA sheet to sag 5 mm was 2.46 (SD, 0.14) N, and that of Medpor was 0.59 (SD, 0.04) N. The power of the PLLA sheet to sag 10 mm was 6.9 (SD, 0.14) N, and that of Medpor was 1.52 (SD, 0.16) N. For two-thirds orbital floor fractures, the power of the PLLA sheet to sag 5 mm was 1.79 (SD, 0.24) N, and that of Medpor was 0.39 (SD, 0.04) N. For 10 mm of sagging, the power of the PLLA sheet was 5.61 (SD, 0.29) N, and that of Medpor was 0.94 (SD, 0.09) N. For sagging of 15 mm, the power of the PLLA sheet was 8.99 (SD, 0.16) N, and that of Medpor was 2.98 (SD, 0.24) N. The PLLA sheet was irreversibly bent when the force reached approximately 8 to 9 N. For Medpor, the degree of sagging during the early stage was larger than at the later stage. In all situations, the supporting power of the PLLA sheet was greater than that of Medpor. The differences were significant in all situations (P = 0.000). The degree of sagging in one-half orbital floor fractures was 2.87 mm for the PLLA sheet and 7.96 mm for Medpor. There was an increased orbital volume of 0.4 mL with the PLLA sheet and 1.19 mL for Medpor. The predicted enophthalmos was 0.41 mm with the PLLA sheet and 1.07 mm with Medpor. The degree of sagging for the two-thirds orbital floor fractures was 4.28 mm for the PLLA sheet and 11.47 mm for Medpor. The increased orbital volume was 0.78 mL for the PLLA sheet and 2.22 mL for Medpor. The predicted enophthalmos was 0.73 mm with the PLLA sheet and 1.93 mm with Medpor. The predicted enophthalmos was below 2 mm with both the PLLA sheet and Medpor for reconstruction of orbital floor fractures; however, it was near 2 mm with Medpor in reconstruction of two-thirds orbital floor fractures. The results of this study show that the PLLA sheet and Medpor were sufficient for reconstruction of one-half and two-thirds orbital floor fractures with a defective posterior part. However, the supporting power of the PLLA sheet was stronger than that of Medpor.

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The fate of an extruded biodegradable mandibular plate, Nazim (2009).
Journal of Plastic Reconstructive and Aestethic Surgeons, 2009; 62(6): 850-852.

After the introduction of biodegradable plates and screws for maxillo-facial fixation over the last decade, there have been many studies related to safety, indications, contraindications, complications, outcomes and other aspects of clinical use. 1 , 2 , 3 , 4 , 5 Degradation by converting into CO2 and H2O via bulk hydrolysis by the liver removes the need of re-operation to remove the plates and screws. Problems associated with metal fixation such as growth disturbances in young children, hypersensitivity to cold exposure, interference with radiological evaluation, stress shielding and bone resorption are no longer considerations.

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Do we have to dissect infraorbital nerve from periorbita in orbital floor fracture?, Hwang and Hwang (2009).
J Craniofac Surg. 2009 Jul;20(4):1260-2.

The aim if this study was to see whether we have to dissect the infraorbital nerve from periorbita in orbital floor fractures.Orbital floors were reconstructed in 174 patients. Among them, 31 patients were treated with horseshoe-shaped synthetic sheets. Preoperative and postoperative findings including hypesthesia, diplopia, Hertel exophthalmometry, and occurrence of complications were checked.After the subciliary incision through skin and orbicularis oculi muscle, the skin-muscle flap was elevated just superficial to the orbital septum to the arcus marginalis. The periosteum was incised and elevated to expose the fracture site. The orbital branch of the infraorbital artery was identified. The periorbita was not separated from the infraorbital nerve, and the orbital branch of the infraorbital artery was preserved. The sheet was trimmed in horseshoe shape as the cleft fits to the infraorbital groove.On physical examination before surgery, diplopia was the most common (58.1%) associated complication, followed by hypesthesia (35.5%), limited ocular movement (9.7%), enophthalmos (3.2%), and hematoma (3.2%).Even if the fracture site is the posterior half, the periorbita does not have to be separated from the infraorbital nerve to avoid injury of the orbital branch of the infraorbital artery. Instead, the fracture site might be covered by a horseshoe-shaped sheet.

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Medial orbital wall reconstruction through subciliary approach: revisited, Hwang et al. (2009).
J Craniofac Surg. 2009 Jul;20(4):1280-2.

The aim of this study is to determine the safety and complication of subciliary approach through the retrospective review of our experiences. From 2005 through 2008, the subciliary skin-muscle flap methods were used in 30 patients undergoing medial orbital wall reconstruction. Preoperative and postoperative ophthalmic findings including diplopia, Hertel exophthalmometry, and occurrence of complications were checked. Resorbable polylactic acid sheet or porous polyethylene sheet was trimmed and molded in L shape, vertical portion to cover the medial wall defect and horizontal portion for stability in orbital floor.In the follow-up of diplopia, half of the patients (3 cases) presenting with diplopia improved during the first month of follow-up, and all of them improved by 6 month. For hypesthesia, all patients improved by 3 months. Enophthalmos of 1 patient improved after operation and did not recur. No patients complained of visible scar 6 months postoperatively, and no ectropion was observed.We think that medial orbital wall could be reconstructed safely through skin-muscle flap subciliary approach without resulting in ectropion or lacrimal canaliculus injury.

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Analysis of orbital bone fractures: a 12-year study of 391 patients, Hwang et al. (2009).
J Craniofac Surg. 2009 Jul;20(4):1218-23.

This retrospective study evaluates 391 patients with orbital bone fractures from a variety of accidents that were treated at the department of Plastic and Reconstructive Surgery, Inha University Hospital, Incheon, South Korea, between February 1996 and April 2008. The medical records of these patients were reviewed and analyzed to determine the clinical characteristics and treatment of the orbital bone fractures.The following results were obtained. The mean age of the patients was 31.1 years, and the age range was 4 to 78 years. The most common age group was the third decade of life (32.5%). There was a significant male predominance in all age groups, with a ratio of 4.43:1. The most common etiology was violent (assault) or nonviolent traumatic injury (57.5%) followed by traffic accidents (15.6%) and sports injuries (10.7%).The most common isolated orbital bone fracture site was the orbital floor (26.9%). The largest group of complex fractures included the inferior region of the orbital floor and zygomaticomaxilla (18.9%). Open reduction was performed in 63.2% of the cases, and the most common fracture reconstruction material was MEDPOR (56.4%) followed by a resorbable sheet (41.1%). The postoperative complication rate was 17.9%, and there were no statistically significant differences among the reconstruction materials with regard to complications. During follow-up, diplopia, hypoesthesia, and enophthalmos occurred as complications; however, there was no significant difference between porous polyethylene sheet (MEDPOR) and resorbable sheet groups.Long-term epidemiological data regarding the natural history of orbital bone fractures are important for the evaluation of existing preventative measures and for the development of new methods of injury prevention and treatment.

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Degradative and mechanical properties of a novel resorbable plating system during a 3-year follow-up in vivo and in vitro, Nieminen et al. (2010).
J Mater Sci Mater Med. 2008 Mar;19(3):1155-63.

We tested the tissue reactions and mechanical strength of a novel biodegradable craniomaxillofacial plating system, Inion CPS, in the course of degradation. Plates and screws composed of L-lactide, D-lactide and trimethylene carbonate were implanted to the mandible and dorsal subcutis of 12 sheep. The animals were sacrificed at 6-156 weeks. Histological evaluation was done using paraffin and methylmetacrylate techniques. Degradative and mechanical properties during the follow-up were measured both of in vivo and in vitro implants. In light microscopy, the in vivo implant material began to fragment at 52 weeks and could not be detected at 104 weeks. No significant foreign body reactions were seen in the mandibles. The dorsal subcutis disclosed mild reactions, which were, however, not of clinical significance. The implants in vitro maintained their entire mass for 26 weeks and lost 63-80% of the mass by week 104. The inherent viscosity of the implants in vitro and in vivo diminished uniformly. The screws retained their shear strength for 12-16 weeks. The plates maintained their tensile strength for at least 6 weeks. The maximum capacity of the plates in 3-point bending tests diminished gradually by 87% in 26 weeks. In conclusion, the plates and screws examined maintain adequate strength for the healing period of a bone fracture or osteotomy, producing no harmful foreign body reactions.

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Stability and morbidity of Le Fort I osteotomy with bioresorbable fixation: a randomized controlled trial, Cheung et al. (2008).
Int J Oral Maxillofac Surg. 2008 Mar;37(3):232-41.

A randomized controlled clinical trial was conducted to compare the use of bioresorbable and titanium mini-plates and screws in Le Fort I maxillary osteotomies for evaluation of clinical morbidity and stability. Forty patients requiring Le Fort I osteotomies were randomly assigned to two groups. One group underwent bioresorbable mini-plate fixation and the other titanium mini-plate fixation. Stability of the maxilla was determined by serial cephalometric analysis at 2 and 6 weeks and at 3, 6 and 12 months postoperatively. Subjective and objective assessment of clinical morbidity was made prospectively. There were no differences in complications between the two fixation materials. Maxillae with bioresorbable fixation were significantly more mobile at the second postoperative week. Bioresorbable plates were initially more easily palpable, but their palpability decreased with time. Titanium plates became significantly more palpable at the 1-year follow-up. There was no difference in neurosensory disturbance between groups. Patients with bioresorbable plate fixation showed significantly more upward displacement in anterior maxilla following impaction and posterior maxilla following downgrafting from the 2nd to 6th postoperative week. The horizontal and angular relapses in the two groups were comparable. Le Fort I osteotomy with bioresorbable fixation results in no greater morbidity than with titanium fixation up to 1 postoperative year.

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INION compared with titanium osteosynthesis: a prospective investigation of the treatment of mandibular fractures, Leonhardt et al. (2008).
Br J Oral Maxillofac Surg. 2008 Dec;46(8):631-4.

We prospectively studied two groups of 30 patients to assess the outcome of treatment of mandibular fractures with the biodegradable INION system compared with osteosynthesis with titanium miniplates. The degree of occlusion, wound healing, and swelling, were noted preoperatively and at 1 week, 6 weeks, and 6 months postoperatively. All fractures healed uneventfully, both clinically and radiologically, and independently of the osteosynthesis used. We found no long-term disturbance of occlusion, but there were twice as many malocclusions in the INION group at one week. We now use a 3-5 day period of postoperative elastic intermaxillary fixation (IMF) to prevent material deformities. Both groups developed problems with wound healing; with INION adequate soft tissue closure combined with appropriate positioning of the plates prevented this. At 6 months a dense swelling developed in some patients in the INION group as a result of biodegradation of the plates. INION plates were biocompatible and strong enough to treat mandibular fractures.

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Bicortical biodegradable screws for rigid fixation of traumatic sagittal split mandibular fracture, Canter and Mavili (2007).
J Craniofac Surg. 2007 May;18(3):626-9.

Rigid fixation is the most important issue in the bone healing process. Although internal metallic bone fixation has become increasingly popular over the past 10 years, the presence of several potential problems of metallic bone implants with the popularity of the use of biodegradable plates and screws for craniomaxillofacial fixation have increased in the last 10 years. Rigid fixation of bony fragments was achieved by bicortical applied biodegradable screws in a patient with a sagittal oblique mandibular fracture. Precise bone reduction was maintained with bicortical applied biodegradable screws in the postoperative period. The postoperative period was uneventful and the patient retained the intraoperatively achieved perfect occlusion within a 9-month follow-up period. In this particular case, the advantages of use of resorbable fixation systems are combined with the advantages of bicortical screw fixation of split osteotomy without sacrificing the stability of rigid fixation.

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Resorbable plates for the fixation of mandibular fractures: a prospective study, Laughlin et al. (2007).
J Oral Maxillofac Surg. 2007 Jan;65(1):89-96.

Purpose: The hypothesis for this prospective evaluation is that resorbable plates are equal to the performance of titanium 2-mm plates, regarding healing of the fracture with bone union and restoration of function. To prove this hypothesis, specific end points will be compared with literature norms for titanium 2-mm miniplate rigid fixation. The primary end point variable for this analysis is the union of the fracture and return to normal function. Secondary end point variables included the incidence of complications such as infection, malunion with malocclusion, soft tissue dehiscence, the need for revision surgery, specific technical challenges, operative time, and the learning curve for the surgeon.

Patients and methods: This prospective study consisted of a sequential enrollment of 50 fractures that met the inclusion criteria of having a fracture of the mandibular body, symphysis, angle, or ramus, and required an open reduction and internal fixation for stabilization and repair. The resorbable plates and screws used consisted of an amorphous injection molded copolymer of L-lactide/D-lactide/trimethylene carbonate (Inion CPS system, Tampere, Finland). Data were collated and compared with literature norms for titanium plates and also compared with nonrigid fixation data from a prospective study performed on a similar population in the same institution.

Results: Clinical and radiographic evaluation indicated union of all fractures at the eighth follow-up visit. Three sites (6%) noted to have clinical signs of infection were treated immediately upon presentation, with fracture union by 8 weeks. There was no need for revision surgery in this series of patients; 12 screw heads fractured during screw placement and were immediately replaced without significant fracture sequelae.

Conclusion: Based on this limited series of patients, the hypothesis formulated for this study was validated.

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Reconstruction of traumatic orbital floor fractures with resorbable mesh plate, Tuncer et al. (2007).
J Craniofac Surg. 2007 May;18(3):598-605.

Various materials such as autogenous bone, cartilage and alloplastic implants have been used to reconstruct orbital floor fractures. A new material is needed because of disadvantages of nonresorbable alloplastic materials and difficulties in harvesting autogenous tissues. In this study safety and value of the use of resorbable mesh plate in the treatment of orbital floor fractures are discussed. Between 2002 and 2004 a total of 17 maxillofacial trauma patients complicated with orbital floor fractures were treated with resorbable mesh plate through subciliary or transconjunctival incisions. Pure blow-out fractures were determined in 6 patients and 11 patients had accompanying maxillofacial fractures. Resorbable plate was easily shaped to fit to the orbital floor by cutting with scissors. Patients were evaluated clinically and with computed tomography scans preoperatively and at 3-, 6- and 12-month intervals postoperatively. Twelve patients had preoperative enophthalmos. Two patients had diplopia that was corrected postoperatively. In all 17 cases there was no evidence of infection, diplopia and gaze restriction postoperatively. Scleral show appeared in three patients by the second postoperative week but resolved totally within 3 to 6 weeks except one patient. In this patient anterior displacement of mesh was evident which caused ectropion and enophthalmos and required re-operation. No any other mesh related problems were seen at 15 months mean follow-up time. The advantage of the resorbable mesh system in orbital floor fracture is the maintenance of orbital contents against herniation forces during the initial phase of healing and then complete resorption through natural processes after its support is no longer needed. Our experience represents that resorbable mesh is a safe and effective material for reconstruction of the selected, non-extensive orbital floor fractures.

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Inion CPS™ Baby


Frontal cranial modeling using endocranial resorbable plate fixation in 27 consecutive plagiocephaly and trigonocephaly patients, Salokorpi et al. (2015).
Childs Nerv Syst. 2015 Jul;31(7):1121-8.

Introduction: Premature ossification of coronal and metopic sutures is treated by fronto-orbital remodeling. Such operations require stable fixation of the reshaped cranial bones. Currently, biodegradable plating systems are used to provide sufficient stability over the time that takes for the osteotomies to ossify. Plates that are placed traditionally on the outer surface of the cranium are often palpable and even visible through the thin overlying skin, compromising the cosmetic results of these operations. Improved aesthetics could be achieved by placing the plates endocranially.

Purpose: This study aimed to evaluate endocranial resorbable plate fixation and its clinical and radiographic results in frontal remodeling cranioplasty for plagiocephaly and trigonocephaly patients with follow-up sufficiently long for the plates to have been completely resorbed.

Methods: A poly(lactide-co-glycolide) (PLGA) resorbable plating system was used on the inner aspect of frontal bone in 27 patients treated for coronal and metopic craniosynostoses. The outcome was evaluated at follow-up visits. The mean follow-up was 79.2 months.

Results: Three patients had complications that required reoperations. None of these complications were related to the endocranial location of the plates. There were no problems with ossification of the osteotomy sites. All but one patient’s outcome was judged as good or excellent.

Conclusion: Placement of resorbable fixation on the endocranial surface of the calvarial bones is safe, stable, and results in satisfactory aesthetics without interfering with the ossification of the cranial bones.

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Distraction osteogenesis with pivot plate in the treatment of scaphocephaly, Nam et al. (2011).
J Craniofac Surg. 2011 Jan;22(1):96-9.

In scaphocephaly, traditional distraction osteogenesis increases only the bitemporal width. We describe distraction osteogenesis with a pivot plate for scaphocephaly, which not only increases the bitemporal width but also decreases the anteroposterior length. Three patients with scaphocephaly were treated using distraction osteogenesis with a pivot plate between January 2005 and June 2006. These children underwent cranial reshaping by gradual distraction using an external distraction device and pivot plate. The distraction rate was 1 mm/d, and the latency period was 5 days. The follow-up period after distraction osteogenesis ranged from 16 to 24 months. No specific complications, such as accidental removal of the distraction devices, infection, or neurologic problems in any patient, occurred. The mean distraction was 45 mm. The mean cranial index was 73.6. Distraction osteogenesis for scaphocephaly is still in the development stage, but it is becoming accepted as a useful method because of its many advantages. Distraction osteogenesis with a pivot plate for scaphocephaly is better than other distraction osteogenesis techniques because it induces increased bitemporal width and decreased anteroposterior length synchronously.

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Surgical treatment of metopic synostosis, Hormozi et al. (2011).
J Craniofac Surg. 2011 Jan;22(1):261-5.

Metopic synostosis is characterized by keel-shaped forehead (trigonocephaly), prominent midline ridge of the forehead, bitemporal narrowing, bilateral retrusion of supraorbits, egg-shaped orbits, low nasal dorsum, and reduced volume of the anterior cranial fossa. The mainstay treatment is early surgical intervention before the age of 12 months, which usually consists of bifrontal craniotomy with bilateral recontouring, lateral advancement, and lateral displacement of the superior orbital rims. Here, we have developed a new simplified technique for surgical treatment of trigonocephaly. A total of 60 cases of trigonocephaly were operated on between January 1995 and January 2010 by the first author. Surgical outcomes were evaluated 6 months after surgery using postoperative photographs and clinical examination notes, and scaling was made using the Whitaker classification. The evaluation showed that 85% of them were in class I, 11.6% were in class II, and 3.3% were in class III. No case was in class IV. Only the last 10 cases received the new surgical technique, and all were in class I. Complication rate was 38.3% for all cases and was only 20% for the last 10 cases, that is, the new technique group. Revision rate for trigonocephaly surgery was 13.3%, and the most common reason was hardware removal. None of the patients from the new technique group underwent revision surgery. We believe that our new technique is fast and easy, can provide sufficient bone graft, and is more useful for older patients (>1 y). Early postoperative results have been promising.

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Biodegradation of Inion fast-absorbing biodegradable plates and screws, Losken et al. (2008).
J Craniofac Surg. 2008 May;19(3):748-56.

Biodegradable plates and screws are recommended for use in surgery of the craniofacial skeleton of children. To be effective and not interfere with growth of the child’s skull, the plates must biodegrade sufficiently to release the holding power of the plate and screw within 1 year. It is also essential that excessive foreign body reaction and cyst formation does not occur when the plates and screws biodegrade. The purpose of this experimental study was to evaluate the rate of biodegradation of Inion CPS Baby biodegradable plates and screws under different clinical circumstances in the rabbit craniofacial skeleton and evaluate their efficacy for use in pediatric craniofacial surgery. Foreign body reaction would be evaluated. Inion baby plates and screws were tested in a rabbit model. Plates were applied to the frontal bone, over a bony defect of the parietal bone, to a nasal bone fracture, and inserted in the subcutaneous space over the occipital bone in thirty 6-week-old rabbits. Six rabbits were euthanized at 9, 12, 15, and 18 months’ postoperative time point and examined for residual plates and screws. Bone from each surgical site was excised, fixed by immersion in 10% neutral-buffered formalin, decalcified in Immunocal solution, and examined by 7-microm paraffin sections stained with hematoxylin and eosin. At 9 months, the plates and screws had effectively biodegraded and no longer had holding power on the bones. Fragmentation of the implant material was noted. Residual implant material was still present on gross and histologic examination in rabbits at 9, 12, 15, and 18 months. Residue of a screw was still palpable in 1 rabbit at 18 months. There was no evidence of cyst formation in any of the examined specimens. Macrophages and giant cells were present in most of the specimens at 9, 12, 15, and 18 months. Findings from the current study revealed a relative short resorption time (9 mo) and normal inflammatory sequelae in an adult rabbit model. These findings suggest that these plates may be used safely in fixing the pediatric craniofacial skeleton.

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Effective correction of frontal cranial deformities using biodegradable fixation on the inner surface of the cranial bones during infancy, Serlo et al. (2007).
Childs Nerv Syst. 2007 Dec;23(12):1439-45.

Purpose: Fixation of cranial bones in pediatric craniofacial surgery with biodegradable materials has developed into an accepted method. However, placing the fixation material on the outer surface of the cranial bone at the frontal cranium in infants can result in suboptimal cosmetic outcomes, as the plates and screws can be palpable. The placement of resorbable fixation devices on the inner surface of the skull would allow for less obvious fixation beneath the skin with a potentially superior cosmetic result. The authors report the use of such resorbable fixation devices on the inner or endocranial aspect of the cranium which appears to be novel.

Materials and methods: Ten patients with the mean age of 14 months (range 7-35 months) were treated with cranial remodeling using poly(lactide-co-glycolide) (PLGA) biodegradable fixation on the inner surface of the cranial bones. Five patients had trigonocephaly, four plagiocephaly, and one brachycephaly. All patients had 3D computed tomography (CT) and clinical photographs done preoperatively and postoperatively at follow-up. The outcome was judged at follow-up by clinical evaluation, photographs, 3D CT, and interview of the parents. The mean follow-up time was 3.5 years (range 0.5-6 years).

Results: The primary recovery was uneventful in all cases. No wound infection occurred, but one patient had a minor skin necrosis which required a single revision operation to correct. The cosmetic outcome was scored as excellent, good, fair, or poor. There was no case with delayed union. Seven out of ten cases were judged as excellent and three as good, none as fair or poor.

Conclusions: The use of resorbable PLGA fixation devices on the inner aspect of the skull appears to provide a satisfactory cosmetic result in this small preliminary group of pediatric patients. Further long-term study of these materials in this specific location in a larger patient group is needed.

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Treatment of a mandibular fracture with biodegradable plate in an infant: report of a case, Senel et al. (2006).
Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006 Apr;101(4):448-50.

Mandibular fractures in infants are rare. Different methods have been described for treatment of fractures of the mandible in infants. Internal fixation of a mandibular fracture with a biodegradable plate in an 8-month-old baby is described. In addition, choices of treatment modality in such cases are discussed.

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Bone Grafting

Inion BioRestore™


Osteogenic medium is superior to growth factors in differentiation of human adipose stem cells towards bone-forming cells in 3D culture, Tirkkonen et al. (2013).
Eur Cell Mater. 2013 Jan 30;25:144-58.

Human adipose stem cells (hASCs) have been recently used to treat bone defects in clinical practice. Yet there is a need for more optimal scaffolds and cost-effective approaches to induce osteogenic differentiation of hASCs. Therefore, we compared the efficiency of bone morphogenetic proteins (BMP-2 and BMP-7), vascular endothelial growth factor (VEGF), and osteogenic medium (OM) for the osteo-induction of hASCs in 3D culture. In addition, growth factors were tested in combination with OM. Commercially available bioactive glass scaffolds (BioRestore) and biphasic calcium phosphate granules (BoneCeramic) were evaluated as prospective carriers for hASCs. Both biomaterials supported hASC-viability, but BioRestore resulted in higher cell number than BoneCeramic, whereas BoneCeramic supported more significant collagen production. The most efficient osteo-induction was achieved with plain OM, promoting higher alkaline phosphatase activity and collagen production than growth factors. In fact, treatment with BMP-2 or VEGF did not increase osteogenic differentiation or cell number significantly more than maintenance medium with either biomaterial. Moreover, BMP-7 treatment consistently inhibited proliferation and osteogenic differentiation of hASCs. Interestingly, there was no benefit from growth factors added to OM. This is the first study to demonstrate that OM enhances hASC-differentiation towards bone-forming cells significantly more than growth factors in 3D culture.

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Three-dimensional evaluation of bone changes following ridge preservation procedures, Clozza et al. (2012).
Int J Oral Maxillofac Implants. 2012 Jul-Aug;27(4):770-5.

Purpose: To evaluate three-dimensionally the bone change following ridge preservation procedures (RPP) using computed tomography (CT).

Materials and methods: Subjects in need of implant therapy were enrolled in the study. The teeth were extracted, and sockets underwent RPP with a bioactive glass (Inion BioRestore, Inion Oy). The patients were scanned with CT within 1 week and 3 months after surgery. Horizontal and vertical radiographic measurements were performed on superimposed CT scans to evaluate bone changes in the alveolar sites during the 3-month period.

Results: Thirteen subjects participated, and 32 teeth were extracted and treated with grafting. Alveolar sites treated with RPP demonstrated a preservation of about 77% of the original width dimensions, with a mean loss of 1.8 ± 1.1 mm in width. Moreover, it was observed that the vertical loss of buccal bone was 2.7 ± 1.1 mm, while the loss of lingual bone was 1.9 ± 1.2 mm.

Conclusions: The CT evaluation was helpful to assess that the bone loss in width was less than the vertical bone loss of both walls 3 months after RPP.

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Calcium phosphate surface treatment of bioactive glass causes a delay in early osteogenic differentiation of adipose stem cells, Haimi et al. (2009).
J Biomed Mater Res A. 2009 Nov;91(2):540-7.

Human adipose stem cells (ASCs) combined with osteostimulative material provide an attractive approach for clinical bone regeneration. The effect of calcium phosphate (Ca-P) surface treatment of three-dimensional bioactive glass scaffolds on the attachment, proliferation, and osteogenic differentiation of ASCs was studied. Three types of bioactive glass scaffolds (nontreated, thick and thin Ca-P treated) were compared. All scaffold types supported ASC attachment, spreading, and proliferation equally as detected by scanning electron microscopy, fluorescence staining, and DNA measurement. Indices of osteogenic differentiation including the expression of osteopontin and alkaline phosphatase (ALP) were consistently higher in the nontreated and thin Ca-P-treated scaffolds when compared with thick Ca-P-treated scaffolds at 2 weeks. ASCs cultured on nontreated bioactive glass scaffolds showed significantly higher ALP activity when compared with both thin and thick Ca-P-treated scaffolds after 1 week in culture, but these differences equalized between the three scaffolds by the 2-week time point. In conclusion, osteogenic differentiation appears to be delayed on the Ca-P surface-treated scaffolds. This delay is more pronounced with thick Ca-P treatment of the scaffolds.

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Rabbit pilot study on the resorbability of three-dimensional bioactive glass fibre scaffolds, Moimas et al. (2006).
Acta Biomater. 2006 Mar;2(2):191-9.

Bioactive glass composed of Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2 is used in this study to manufacture three-dimensional glass fibre scaffolds for a synthetic bone filler material for the treatment of bone defects. The glass is characterized by a large working range, which is the temperature interval at which forming of glass can take place. A preliminary in vivo study on New Zealand skeletally mature rabbit’s tibia is reported here. Bone defects were prepared in the medial surfaces of the diaphyses of the tibia. For the first time melt derived three-dimensional bioactive glass fibre constructs were used to fill the cavities. The different implants investigated here were a scaffold with a porosity of 45-50%, scaffold with a porosity of 55-60% and morsels with a porosity of 55-60%. The implanted bone substitutes were dissected after 6 months and evaluated by histological and synchrotron radiation micro tomography analysis. PerioGlas and empty defects were used as positive and negative controls, respectively. The result was that the surgically created tibial defects were healed and new bone formation was found in the medullary cavities. Despite the intrinsic limitations of a pilot study, the preliminary results indicate that in 6 months the glass fibre scaffolds are completely resorbed and that the osteoconductive properties of the filling material are strictly correlated with the structural and morphological characteristics of the bone substitute.

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Inion S-1™


Outcomes observed during a 1-year clinical and radiographic follow-up of patients treated for 1- or 2-level cervical degenerative disease using a biodegradable anterior cervical plate, Chen et al. (2016).
J Neurosurg Spine. 2016 Aug;25(2):205-12.

The purpose of this study was to present an initial surgical experience in the management of 1- or 2-level degenerative disc disease of the cervical spine using biodegradable anterior cervical plates (bACPs) in anterior cervical discectomy and fusion (ACDF). The authors also aimed to provide insight into this critical and controversial clinical issue by clarifying outcomes for patients receiving bACPs and by comparing their outcomes with those achieved using a traditional metallic anterior cervical plate (mACP) implant.

A retrospective review was conducted for 2 series of patients who had undergone ACDF using either bACP (31 patients, 38 segments) or mACP (47 patients, 57 segments) instrumentation. The patients were followed up for a mean 13.5 ± 0.9 months (range 12–18 months) in the bACP group and 14.8 ± 1.5 months (range 14–22 months) in the mACP group. Clinical outcomes were determined according to scores on the visual analog scale (VAS), the modified Japanese Orthopaedic Association (mJOA) scoring system, and Odom’s criteria. Radiological images were used to assess fusion rates, intervertebral height, Cobb’s angle, and the width of prevertebral soft tissue.

Both VAS and mJOA scores were significantly improved at each follow-up in both groups. Excellent or good results according to Odom’s criteria were achieved in 93.5% (29/31) of patients in the bACP group and 93.6% (44/47) of patients in the mACP group. At 6 months postoperatively, the fusion rate was 94.7% (36/38) in the bACP group and 96.5% (55/57) in the mACP group, but subsidence of the intervertebral space at the surgical level was more evident in the bACP group. Angulation, as measured by Cobb’s angle, demonstrated obvious healing in both groups, while better maintenance was observed in the mACP group. The local inflammatory reaction was uneventful during follow-up. Dysphonia and dysphagia were observed in both groups during the follow-up.

The relatively comparable early clinical and radiographic outcomes and the overall acceptable complication rates for bACP and mACP use suggest that bACPs could be used as alternative instruments in ACDF. Mild graft resorption was noted without evidence of symptoms. However, the prospective efficacy of biodegradable instrumentation can only be elucidated with longer-term observation.

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Long-term follow-up of anterior cervical discectomy and fusion with bioabsorbable plates and screws, Rodrigo et al. (2015).
Clin Neurol Neurosurg. 2015 Sep;136:116-21.

Objective: Anterior cervical discectomy and fusion (ACDF) is an accepted technique for the management of cervical spinal degenerative disease. Recently, new resorbable materials have been proposed for the anterior cervical fusion to eliminate some of the disadvantages and complications of metal plates. The aim of our study was to evaluate the long-term clinical results of the ACDF implants made out of bioabsorbable materials.

Methods: We performed a retrospective descriptive study of a series of 17 ACDF patients operated with the Inion S-1™ resorbable screws and plates (made out of biodegradable copolymers composed of l-lactic acid and d,l-lactic acid 80/20) 5-7 years ago. The mean age of the patients was 45 years. A single-level procedure was carried out in 13 patients and a double-level procedure in four patients, and the most commonly fused level was C5-C6. Clinical background, preoperative and postoperative symptoms, previous trauma, complications, radiographic fusion and condition of the prevertebral space (preoperative and postoperative) were analyzed.

Results: We observed a good fusion rate and stability using resorbable plates and screws. None of the patients had associated severe complications such as adjacent tissue edema or infection, or had to be reoperated due to failure or migration of the used implants.

Conclusions: The results of this retrospective clinical long-term follow up demonstrate that cervical fusion can be successfully achieved using resorbable implants.

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Comparison of bioresorbable and titanium plates in cervical spinal fusion: early radiologic and clinical results, Nabhan et al. (2009).
J Spinal Disord Tech. 2009 May;22(3):155-61.

Study design: This is a prospective, randomized, and controlled study, approved by the local ethical committee of Saarland (Germany), no. 209/06.

Objective: The aim of this study was to compare clinical results, segmental motility, magnetic resonance imaging (MRI) compatibility, and change of the bone density of a cervical spine segment that was treated with either bioresorbable or titanium plates in single level.

Summary and background data: Anterior cervical discectomy and fusion including plate fixation is an accepted technique for treatment of symptomatic degenerative disc disease. Titanium plates have been used but cause imaging artifacts. Radiolucent bioresorbable plates and screws were developed to reduce the imaging artifacts associated with titanium.

Methods: Forty patients with single level cervical radiculopathy were randomized to anterior discectomy and fusion with bioresorbable plate (19 patients, study group) or titanium plate (18 patients, control group). Follow-up used a visual analog scale (VAS) with regard to brachial pain and Neck Disability Index (NDI) for neck pain. Radiostereometry was performed immediately postoperative and after 6 weeks, 3, and 6 months. MRI of the cervical spine was obtained immediately postoperatively at 3 and 6 months to assess hematoma, infection, and swelling. Computed tomography of the operated cervical spine segment was performed to assess bone density, expressed in Hounsfield units.

Results: Three-dimensional analysis of segmental motion (medio-lateral, cranio-caudal and anterior-posterior) did not reveal any statistical difference between both groups at any time postoperatively (P>0.05). Fusion rate and speed evaluated on Radiostereometric analysis and computed tomography of cervical spine segment were similar in both groups. MRI of cervical spine did not show any pathology, especially hematoma and infection. The VAS and NDI did not differ between both groups after 6 months (P>0.05).

Conclusions: Anterior plate fixation by using a bioresorbable plate has the same fusion progress and stability as titanium. During the study, no complications like soft tissue swelling and infection occurred.

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Bioabsorbable instrumentation for single-level cervical degenerative disc disease: a radiological and clinical outcome study, Tomasino et al. (2009).
J Neurosurg Spine. 2009 Nov;11(5):529-37.

Object: The authors present the radiological and clinical outcome data obtained in patients who underwent single-level anterior cervical discectomy and fusion (ACDF) for cervical spondylosis and/or disc herniation; bioabsorbable plates were used for instrumentation. The use of metallic plates in ACDF has gained acceptance as a stabilizing part of the procedure to increase fusion rates, but when complications occur with these devices, the overall effectiveness of the procedure is compromised. As a possible solution, bioabsorbable implants for ACDF have been developed. This study investigates the feasibility and radiological and clinical outcomes of the bioabsorbable plates for ACDF.

Methods: The radiological and clinical outcomes of 30 patients were investigated retrospectively. All patients presented with cervical radiculopathy or myelopathy and underwent single-level ACDF in which a bioabsorbable anterior cervical plate and an allograft bone spacer were placed at a level between C-3 and C-7. Radiological outcome was assessed based on the fusion rate, subsidence, and Cobb angle of the surgical level. Clinical outcome was determined by using a visual analog scale, the Neck Disability Index, and the Odom criteria.

Results: There were no intraoperative complications, and no hardware failure was observed. No signs or symptoms of adverse tissue reaction caused by the implant were seen. Two reoperations were necessary due to postoperative blood collections. The overall complication rate was 16.7%. After 6 months, radiographic fusion was seen in 92.3% of patients. Subsidence at 11.3 +/- 7.2 months was 3.1 +/- 5.8 mm (an 8.2% change over the immediately postoperative results), and the change in the sagittal curvature was -2.7 +/- 2.7 degrees . The visual analog scale score for neck and arm pain and Neck Disability Index improved significantly after surgery (p < 0.001). Overall at 19.5 months postoperatively, 83% of the patients had favorable outcomes based on the Odom criteria.

Conclusions: Absorbable instrumentation provides better stability than the absence of a plate but graft subsidence and deformity rates may be higher than those associated with metal implants. There were no device-related complications, but adverse late effects cannot be excluded. The fusion rate and outcome are comparable to the results achieved with metallic plates. The authors were satisfied with the use of bioabsorbable plates as a reasonable alternative to metal, avoiding the need for lifelong metallic implants.

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Use of resorbable implants for symptomatic cervical spondylosis: experience on 16 consecutive patients, Franco et al. (2007).
J Neurosurg Sci. 2007 Dec;51(4):169-75.

Aim: The aim of this study was to evaluate the results of a consecutive series of 16 patients affected by degenerative cervical spondylosis and operated on by anterior cervical discectomy and fusion (ACFD) by means of anterior bioresorbable plate and screws. Further, the authors compared the results in these patients with a series of 13 patients also affected by degenerative cervical spondylosis in whom arthrodesis was obtained by means of cages without plates.\

Methods: The series included 8 males and 8 females aging from 37 to 69 years, operated from June 2003 to September 2004. They showed signs of cervical myelopathy, radiculopathy or both. The ACDF was performed with the insertion of dense cancellous allograft and application of anterior bioresorbable plate and screws (group A). The group B series included 9 males and 4 females aging from 50 to 77 years, all affected by the same pathology of group A patients and operated on in the same period of time. In these cases the ACDF was followed by the insertion of cages without anterior plates.

Results: The retrospective analysis of our series showed lack of soft tissue reaction, with safeguarding of the vertebral body and disc space height. The degree of alignment of the cervical spine was also preserved, with a good rate of fusion and a good clinical outcome in both series of patients.

Conclusion: The use of a cervical plate increase stability and rate of fusion when added to the interbody device; while the use of a metallic plate may be responsible for several shortcomings, a resorbable plate may overcome these problems.

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In vitro comparison of bioresorbable and titanium anterior cervical plates in the immediate postoperative condition, Freeman et al. (2006).
J Spinal Disord Tech. 2006 Dec;19(8):577-83.

Bioresorbable plates have recently been used with anterior cervical discectomy and fusion (ACDF). Compared with metallic plates, bioresorbable plates provide segmental stabilization with minimal imaging artifact, eventual resorption, and increased load sharing. The objectives of the present study were to determine whether a bioresorbable plate can withstand simulated physiologic static and cyclic loading, to compare the reduction in flexibility provided by bioresorbable and titanium plates, and to quantify load sharing between the plate and spine with graft. Sixteen human cervical motion segments were tested to +/-2.5 Nm in flexion-extension, lateral bending, and axial rotation. Range of motion (ROM) was measured (1) in the intact state, (2) with ACDF without plating, (3) after addition of either a bioresorbable or titanium plate, and (4) after 500 cycles of combined flexion-extension and axial torsion. Load sharing was evaluated by applying the same fixed rotation both without and with the plate, and was calculated as the moment resisted by the uninstrumented ACDF expressed as a percentage of the plated ACDF state. No plate failures or graft migration occurred during testing. Compared with the uninstrumented ACDF, bioresorbable plates reduced mean ROM by 49% in flexion-extension and 25% in lateral bending, with very little change in torsion. Titanium plates reduced uninstrumented ACDF ROM by 69% in flexion-extension, 45% in lateral bending, and 27% in torsion. Differences between bioresorbable and titanium plates were significant in flexion-extension and lateral bending. Cyclic loading did not significantly change ROM for either plate. More moment was shared in lateral bending by the spine/graft with bioresorbable plates (78%) compared with titanium plating (63%). Bioresorbable plates contained an intervertebral graft, provided some stabilization, remained intact throughout the simulated immediate postoperative loading, and shared more load with the graft and osteoligamentous spine than titanium plates.

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