Biodegradable solutions to surgery
Surgical biomaterials are essential in treating severe fractures and injuries, or treating congenital malformations or surgical defects in humans. The first materials used as substitute to body’s own tissue were wood and animal tissues. During decades of development, the modern inert metals such as stainless steel and titanium were developed. These two materials revolutionised surgical treatment of injured bone. Nowadays it is possible to stabilise fractures and surgical defects with for example metallic plates, screws and rods. However, using metal inside the human body is not without problems.
Although metals are easy to implant, they are difficult to contour to the exact patient anatomy. Elaborate tools have been developed to enable slight modification of the implant geometry during surgery. Also a wide selection of different implant sizes and shapes have been made available to overcome this issue. Therefore, a hospital shelf is packed with numerous different implant options, shapes and sizes.
Postoperative follow-up of patient healing is commonly done using imaging techniques such as radiographs. All metals interfere with these imaging techniques and therefore it is not possible to check bone healing after a metallic implant has been put in place.
Metals are strong. They are much stronger than bone. Initially this was thought to be an advantage, but soon it was discovered that too strong implants such as those made of stainless steel would cause bone loss (due to “stress shielding”) leading to a risk of re-fracture at the same site. Revision surgery to bone which has already been stabilised with a metallic implant is complicated. It requires removal of the existing implant and re-stabilisation of the bone.
Removal of implant is always traumatic to bone and tissues. It also requires much from the patient who needs to recover from a secondary surgery. Removal of metal implants is especially common in growing children because an inert and strong metal implant may hinder bone growth.
Lactic acid based implants have been used in clinical practice to treat ankle fractures since 1988. Since then numerous scientific and clinical publications have shown biodegradable materials a success in treating injuries to the bone and soft tissues. Essentially, biodegradable materials are the next generation osteosynthesis materials which have the advantages of metal, but they do not interfere with imaging, are strong enough for long enough, and they biodegrade completely. A surgeon can monitor bone healing easily with imaging techniques. The implants do not cause bone loss due to stress shielding, and they allow micromotion which is essential for new bone formation.
A major advantage of biodegradable implants to surgeons is that they are very easily contoured to the exact patient anatomy. Also shaping of the implant is easy. Each implant is therefore always a custom implant, and there is no need to have as many implant boxes on the hospital shelf as with metallic products.
Inion uses its modern Inion® family of biodegradable materials which have years of evidence of safe clinical use in humans to offer products in four different product lines: