A Cohort Study of Bioabsorbable Screws for Syndesmosis Fixation Fixation in Ankle Fracture

Surgical Technique The operation requires the patient positioned supine with a sandbag beneath the ipsilateral buttock to internally rotate the leg to permit the ankle and foot to sit in neutral. Appropriate antibiotics as per local guidelines should be administered prior to insufflation of a tourniquet. Fluoroscopy is required throughout the procedure and should be positioned on the contralateral side to the injured limb to improve the access for the surgical team.

Depending on the injury type the fibula may or may not require fixation (maissoneuve or weber B/C type injury). This will be performed if necessary via a direct lateral approach to the fibula, and fixation as per surgeon preference appropriate for the fracture configuration. Typically a lag screw and one-third tubular neutralisation plate is used. Plates should be applied to the posterolateral surface of the fibula to permit passage of the syndesmosis screw through the plate and for increased mechanical stability. Following this the syndesmosis will be reduced with the foot plantigrade using large pointed reduction forceps with or without a K-wire. Medial malleolar fixation, if required, is performed after fibula fixation.

Bio-absorbable screw fixation A single 4.5 mm fully threaded ActivascrewTM (2094913CE01) is placed through four cortices if the fibula fracture is being fixed, through the plate if feasible. Two are used in the case of high fibula or maissoneuve injuries. These will all be through four cortices. A countersink may be used. The screws should be placed parallel to the tibial plafond, 2-4cm proximal to the tibio-talar joint and 30° from posterior to anterior. In the case of fibula fixation this should be though the plate if feasible. The reduction of the syndesmosis and appropriate placement of the positioning screw(s) should be checked intra-operatively with fluoroscopy. The syndesmosis is reduced, using reduction forceps. A hole is drilled with the 3.5mm drill, then tapped with the 4.5mm tap and measured. The ActivascrewTM holder and screwdriver are used to pick up and insert the desired screw. Once the screw is in position the insertion adapter is removed and discarded.

Standardised rehabilitation protocol Post operatively the patient remains non weight-bearing in a Plaster for a total of 6 weeks with a cast change, wound check and removal of sutures at 2 weeks. Following this the patient would then remain partial weight bearing in a protective boot for a further 6 weeks. The patients should be prescribed 6 weeks of Low Molecular Weight Heparin for venous thromboembolic prophylaxis as per local protocol.

Sample size considerations A total number of 40 patients should be sufficient to assess the outcome of fixation using this device.

Patients selection and enrolment Patients will be thoroughly screened to assess their suitability for the study and must fit the inclusion and exclusion criteria.

Inclusion criteria

• • Patient has a Weber C fibula fracture with or without a medial malleolus fracture and evidence of radiological syndesmotic widening on intra-operative stressing

• Patient has a Weber B fracture with evidence of syndesmosis widening radiologically on stressing intra-operatively
• Patient has a maissoneuve type injury with evidence of syndesmotic diastasis
• Patient mobilises independently, with or without aids.
• Patient has given formal consent to be involved in the trial and has completed the study consent form
• Patient is likely to comply with study requirements
• Patient is over the age of 18 years and under 65 years

Exclusion criteria

• • Immobility

• Presence of a posterior malleolus fracture involving >25% of articular surface
• Open fractures
• Pathological fractures
• Other fractures involving the same lower extremity
• Patient unwilling to give informed consent to be included in the trial
• Patient has other injuries that would influence the study
• Any ankle fracture that the treating surgeon feels inappropriate to be included in the study