Screw Versus Tightrope Syndesmotic Injury Fixation in Weber C Ankle Fractures. A Prospective Randomized Study.

The aim of our study is to compare two different syndesmosis transfixation methods in AO/OTA Weber C ankle fractures. Screw fixation is widely and mostly used transfixation but suture-button is also shown to be a biomechanically stable and probably more physiologic transfication method. It is shown that even 50 % of the syndesmosis srews and thus fibulas are in malposition. With more physiologic suture-button transfixation this malposition is thought to be less commmon. There is no studies comparing screw and suture-button syndesmosis transfixation methods in AO/OTA Weber C ankle fracture patients.

Our hypothesis is that 50% of screw fixed fibulas but only 5% of suture-button fixed fibulas are in malposition assessed in the intraoperative computed tomography. Malposition is assessed to present if difference between fractured and non-fractured side is at least 2 mm in the tibiofibular joint. Thus, the sample size is assessed to be 19 patients per group (alpha=0.05, Beta=0.2, 20% drop out).

All skeletally mature patients (16 years or older) with AO/OTA Weber C type fractures operated within a week after trauma are included into the study. Exclusion criteria are previous ankle fracture, concomitant tibial fracture, diabetes with peripheral neuropathy, pathological fracture or inadequate co-operation.

After bony fixation the tibiofibular transfixation is randomly performed either by a 3,5 mm tricortical screw or a suture-button (TightRope). An intraoperative computed tomography is imaged from the both ankles of all patients. The operation is continued with six weeks casting without weight-bearing.

Clinical outcome was assessed using the Olerud-Molander scoring system, RAND 36-Item Health Survey, and Visual Analogue Scale (VAS) to measure pain and function after a minimum 1-year of follow-up.