Outcomes of Posterior Malleolus Fractures

The aim of this study was to evaluate clinical outcomes and complication rates of patients who had sustained an unstable ankle fracture with a posterior malleolus fracture (PMF) and without (N-PMF). Adult patients (> 16 years) presenting to a single large academic trauma centre between 2009 – 2012 with an unstable ankle fracture requiring surgery were identified. Data collected were patient demographics, fracture classification and clinical outcomes. There were 675 patients in the study cohort. The mean age was 48.5 years (range, 16–92) and 59% (n=395/675) were female. Of the total cohort, 63.9% (n=431/675) had an associated PMF. Of those fractures with an associated PMF, 85% (n=367/431) did not undergo fragment specific fixation. There were no statistically significant differences between groups with regards further surgery secondary to complication (N-PMF 5.7%% n=14/244 vs PMF 7.5% n=32/431; p=0.403) or infection (N-PMF 7.8% n=19/244 vs PMF 8.4% n=36/431; p=0.796). Patients with a PMF were significantly more likely to develope PTOA (N-PMF 27.0% n=66/244 vs PMF 54.5% n=235/431; p<0.001). However, only 1.2% (n=3/244) of patients in the N-PMF group versus 3.0% (n=13/431) in the PMF group required an ankle fusion (p=0.190). In this large cohort of patients, a PMF did not increase the risk of further surgery secondary to a complication despite 85% not undergoing fragment specific fixation. Although patients with an associated PMF were twice as likely to acquire post-traumatic osteoarthritis, this did not equate to an increased rate of late intervention in terms of ankle fusion, which was overall very low (3.0%).