The reliability of posterior malleolar ankle fracture assessment: a unique perspective

Aim: This study aims to elucidate the pathology of PMFs in the South African population, establish correlations between fracture patterns and international classification guidelines and evaluate the interobserver reliability of current classifications.

Methods: A retrospective review was conducted in a multicentre analysis over a one-year period from January 2019 to December 2019 at our institution. Computer tomography scans for foot and ankle injuries were reviewed, and posterior malleolus fractures were included. Pathoanatomical data was collected and analysed according to known classification systems and subsequent treatment modalities evaluated. A panel of observers individually reviewed radiographic data to determine interobserver reliability.

Results: A total of 71 patients were included with a mean age of 41 ± 13.4 years (range 18-78) and a female predominant population (69%). A greater proportion of injuries were high energy (23.9%), with significant fragment comminution (53.5%), and half (52.1%) of all injuries were subluxated/dislocated at presentation. A total of 93% of injuries were managed operatively, despite theatre access limitations resulting in significant delays to fixation (19.1 days). Despite good pathoanatomical agreement with most international classifications, interobserver reliability was poor (Krippendorff α-coefficient < 0.667). Inconsistent treatment patterns in operative and non-operative strategies are reported.

Conclusion: A unique patient population of younger, female individuals incurred posterior malleolar fractures due to higher energy mechanisms of injury. Whilst injury patterns were mostly comparable, significant interobserver variability was noted. Resource limitations, diagnostic challenges, poorly defined and inconsistent treatment strategies, inevitably impact outcomes within the South African population.

Level of evidence: Level III.