Open reduction and internal fixation of the posterior malleolus fragment via the posterolateral approach is radiologically superior to 'A to P' screw fixation.

Purpose: Functional outcome in trimalleolar fractures is largely correlated to the reduction of the posterior fragment. Until recently, fixation was mainly performed for large fragments, by percutaneous anterior to posterior ('A to P') screw placement after closed reduction. Nowadays, ORIF via a posterolateral approach seems to gain in popularity. The aim of this study was to compare the postoperative photographs of operated trimalleolar fractures after either fracture treatment method, for fracture diastasis and step-off.

Material And Methods: All consecutive patients with trimalleolar fractures, including posterior fragments of >5% of the articular surface and operated between 2007-2013 were analysed on size of posterior fragment, post-operative gap and step-off by three observers. The patients were divided into three groups; A to P screw fixation, ORIF via the posterolateral approach and no posterior fragment fixation at all.

Results: 180 patients with trimalleolar ankle fractures were included for analyses. Twenty five posterior fragments were fixated percutaneously from anterior to posterior (group 1) and 51 underwent open reduction and internal fixation through a posterolateral approach (group 2). 104 patients underwent no posterior malleolus fixation (group 3). The average size of posterior fragment was 34% in group 1, 27% in group 2 and 16% in group 3. A postoperative step-off >1 mm was found in 40% (group 1), 9% (group 2) or 34% respectively (group 3).

Conclusions: Fixation of the posterior malleolus through an open posterolateral approach leads to better radiological results as compared to percutaneous 'A to P' screw fixation or no fixation at all.