A Retrospective Review of Clinical Outcomes Comparing Unstable Ankle Fractures With and Without a Posterior Malleolus Fracture
N Heinz, S Fredrick, A Amin, A Duckworth, T White
Background: The aim of this study was to evaluate the clinical outcomes and complication rates of patients who had sustained an unstable ankle fracture with a posterior malleolus fracture (PMF) and without (N-PMF).
Methods: All adult patients presenting to a single large academic trauma centre from 2009-2012 with an unstable ankle fracture requiring surgery were identified. Data collected included patient and injury demographics, fracture classification, posterior malleolus fracture articular surface percentage involvement (ASPI) measured from the lateral plain radiograph, and clinical outcomes. Clinical outcomes included infection rates, re-operation rates and incidence of osteoarthritis post-surgery.
Results: There were 1213 patients in the study cohort. Mean age was 47.8 years (16.093.0) and 55.3% (n=671) female. Of the total cohort, 60.2% (n=730) had an associated PMF. These were distributed into ASPI 0-19% (552/730 [75.6%]), 20-33% ASPI (102/730 [14.0%]) and >33% ASPI (76/730 [10.4%]). For all PMFs, 86% (n=628) did not undergo fragment specific fixation. According to ASPI, no specific fixation was used in 98.4% (n=543/552) for ASPI <20%, 67.6% (n=69/102) for ASPI 20-33% and 21.1% (n=16/76) for ASPI >33%. Mean follow up for the study cohort was 1.4 years post injury. There were no statistically significant differences for re-operation (NPMF 20.2% [98/483] vs PMF 22.5% [164/730]; p=0.367) or infection rates (NPMF 5.8% [28/483] vs PMF 6.2% [45/730]; p=0.792). Patients with a PMF were statistically more likely to develop osteoarthritis (NPMF 25.1% [121/483] vs PMF 48.8 % [356/730], p<0.001). Overall, 10/1213 (0.8%) patients required ankle fusion.
Conclusions: The presence of a PMF does not affect the overall re-operation and infection rates in patients with a surgically managed unstable ankle fracture with a conservative approach to fixation in a large cohort of patients. The presence of a PMF does increase the risk of post-traumatic osteoarthritis, however, and the effect on patient reported outcome measures remains unclear.
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