Inion^® OTPS^TM - Frequently Asked Questions

Patients, when given a choice, usually voice a preference for a biodegradable implant rather than for one that remains permanently in their body or enduring a second removal procedure.

They are made of a blend of rigid and elastic polymers selected for their strength, malleability and degradation properties.

Polymers consisting of only one kind of repeating units are called homopolymers.

Copolymers are formed from two or more different repeating units.

TMC will add ductility to Inion implants.

Yes, TMC is used as a co-monomer in various wellknown products like: Maxon®, Suretac®, Endo Screw®

Most problems that have been reported in printed publications were thought to be due to the fast degradation of polymers. Inion Optima^TM Materials used in all of the implants have been tailored to degrade gradually in each application. In addition, Inion materials are completely or substantially amorphous, even after processing, and therefore are not crystalline or semi-crystalline.

The implants initially lose molecular weight, then strength and finally mass.

The implant mass usually starts to reduce at 35 weeks. As a guide the resorption times of the implants are 2 to 4 years.
 

The implants degrade by hydrolysis and over a period of time are metabolised into carbon dioxide and water, which is then exhaled and excreted.

Crystalline polymers have a regular internal structure and because of the orderly arrangement are slow to degrade. Amorphous polymers have a random structure and are completely and more easily degraded. Semi-crystalline polymers have crystalline and amorphous (random structure) regions. Hydrolysis begins at the amorphous area leaving the more slowly degrading crystalline debris. These crystalline regions (crystals) are extremely small. Inion Optima TM materials are completely or substantially amorphous – the ideal for biodegradable implants.

No. All Inion implants are packaged for single use only. This prevents the potential cross infection risk and alleviates problems of decontamination, which are of increasing concern due to HIV and vCJD.

No. The screw holes can be seen in post operative X-rays.

Optima^TM is the name of Inion’s family of materials. The Inion Optima^TM materials are blends of polymers to give different combinations of strength, toughness (malleability) and degradation profiles to meet particular clinical requirements

Inion OTPS^TM stands for Orthopaedic Trauma Plating System. All trauma products belong to the OTPS product group.

The Inion OTPS^TM system loses most of its strength between 18  and 36 weeks. At 36 weeks they will have lost 90% of their strength and at that time resorption increases.

As with metal fixation methods of fractured ankles patients need to have some form of additional external immobilization ( for examble, plaster cast) and be non weight bearing at the beginning. Post operative rehabilitation should be the same as with other fixation methods.

Yes but they need to be “activated” first by heating in the water bath. “Activating” the plate by heat changes it from being brittle to malleable.  After heating in the bath the plates are very malleable but as they cool they begin to feel stiffer and can be adapted using plate benders if required. They can be put back in the water bath at any time during the procedure to heat again (reactivate). If dipped in for a few seconds the plates will just soften. If left in the bath for 5 seconds they will return to their original shape.

The Inion Thermo+ 70 C degree water bath is used to activate the ankle and mesh plates while the Thermo water bath for the mini plating system is set at 55 C degrees.

Yes. Plates are more brittle before heating. To maintain the desired position of the bone fragments it is essential that the plate is adapted precisely . It is therefore recommended that surgeons do activate the plate.

Yes.

Yes. They can be cut to the required length with surgical scissors or wire cutters. However, the plates should be activated prior to cutting as beforehand they are quite brittle. 

It is necessary to tap when using resorbable implants.  

A new screw of the same size can be inserted following re-drilling and tapping directly into the original screw position if needed.

This makes screw insertion easier and smoother by flushing away debris caused by the drilling and tapping.

Providing the screws heads have not been misshapened the screws can be unscrewed and removed. If it is not possible to remove them, the heads can be taken off and the plate removed for repositioning.

The drilling and tapping technique is critical for good screw engagement. Drilling must be mono-axial (one direction) with a single, smooth, in-and-out movement. If the drill is left running in the bone the hole will become too large. The tapping, which is done to cut threads in the bone for the engagement of the screw, must be done gently and slowly, without undue movement or force. After tapping to the required depth, the tap must be gently unscrewed and not pulled out.  

Other reasons for the non-engagement of screws are:

• bone is too soft (can be found close to fracture sites)

• “whipping” of the drill, which makes an eccentric hole (check drill handpiece before the start of the procedure)

It is important that the screws are NOT overtightened as this can cause the fine pitch to pulp the bone between the threads so the screws can't grip.

Surgeons are used to the feel of metal, which requires less delicate handling and where the screws are self-tapping. They soon learn to get the feel of OTPS screws and to recognise when the screw is “binding” in the bone and the amount of pressure they can apply.

No.

As stated in the IFU, Inion OTPS^TM implants are not intended for use in patients who have active or potential infection. Just as when using metal implants, these conditions increase the risk of post operative wound infection. Inion OTPS^TM implants are also contraindicated in patients who have conditions that include a limited blood supply, insufficient quantity or quality of bone; and where patient cooperation cannot be guaranteed (for example, alcoholism, drug abuse).

The idea is that the screw maintains the position of the fibula and tibia so that healing of the ligamentous syndesmosis can occur meanwhile the additional external immobilization (i.e., plaster cast) supports/protects the fixation from loading. When the plaster cast is removed and the patient starts bear full weight the screw can be expected to break/allow normal joint function without need for additional implant removal surgery.

Please carefully follow the guidelines in the IFU.

K-wire should always be used for predrilling, and an x-ray check should be made to confirm correct location of the K-wire before the final drill hole for the screw is created by drilling over the K-wire with a cannulated drill bit. Tapping fully the entire drill hole and through all involved cortices is very important. If tapping is improperly performed, screw insertion may not be possible to complete and the screw can break during insertion. In addition, after tapping, the drill hole should be rinsed with sterile saline to flush out bone debris before screw insertion. The cannulated syndesmosis screws should always be inserted over a K-wire to ensure correct screw placement and to provide extra support to the cannulated screw during its insertion. The screw should not be overtightened. It is also very important not to rotate the fibula when inserting the syndesmosis screw as this results in the screw insertion being forced. The screw is then under pressure and can break. If this does happen a new screw of the same size can be inserted following re-drilling and tapping directly into the original screw position. It is important for surgeons to practice inserting a biodegradable syndesmosis screw into a Sawbones ankle before use on a patient as they do handle differently from metal.

Inion OTPS^TM  screws must not be used to secure any plates and meshes other than Inion's (for example, metal plates). However, while asyndesmosis screw can be placed through a plate it’s function is not to secure the plate but rather to fix the ligament. Therefore, in this application it is possible to use a resorbable syndesmosis screw at the same time as a metal plate is used to fix a fibular fracture.

Consider using a countersink in this area. Also, when using fully threaded screws the heads can be cut off once insertion is complete.      

It is recommended that 2 pins are used to fix unstable factures. Place 2 K-wires at the start to stabilise the fracture and then replace each with a pin in turn. Alternately, it may be possible to use a bone clamp.

The surgeons who are using our products do not find this a problem as the use of guide wires  enables them to use imaging during surgery. They can also use imaging as they tap and drill to judge how deep the implants will be placed.

Drug and cosmetic (D&C) Green No. 6 is cleared by US FDA as a colour additive in certain medical devices. D&C Green No. 6 can be safely used in amounts up to 0.1% weight of PGA suture or 0.21% of Glycolide and TMC copolymer sutures. Inion uses less than these amounts in its implants.