A Retrospective 10-year Review of Patient Reported Outcome Measures 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 long-term outcomes of patients who had sustained an unstable ankle fracture with a posterior malleolus fracture (PMF) and without (N-PMF).

Methods: 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 demographics, fracture classification, posterior malleolus fracture articular surface percentage involvement (ASPI) measured from the lateral plain radiograph, and management. Patient reported outcome measures (PROMs) were obtained at a minimum of 10 years postsurgery. The primary outcome was the Olerud Molander Ankle Score (OMAS). Secondary outcomes were Manchester- Oxford Foot Questionnaire (MOXFQ), EuroQol-5D, infection and re-operation rate.

Results: There were 304 patients in the study cohort. Mean age was 49.6 years (16.378.3) and 67% (n=204) female. Of these, 67% (n=204) had a PMF. These were distributed into an ASPI 0-19% (156/204 [76.5%]), 20-33% ASPI (27/204 [13.2%]) and >33% ASPI (21/204 [10.3%]). Overall, 10% of these (22/204) were managed with fragment specific fixation (1/22 ASPI<20%, 6/22 ASPI-20-33%, 15/22 ASPI>33%). At a mean of 13.8 years (11.3 - 15.3) the median OMAS score was 85 (IQR 60 -100). There was no difference in the OMAS between the N-PMF and PMF groups (85 [IQR 56.25 - 100] vs 85 [IQR 61.25 - 100]; p = 0.580). No statistical differences were found in the MOXFQ (p=0.643), EQ-5D (p = 0.720) and EQ-5D-VAS (p=0.224). There were no differences between the N-PMF and PMF groups for infection (6% vs 4%; p=0.417) or re-operation rates (4% vs 2%; p=0.297).

Conclusions: The presence of a PMF does not affect the long-term patient reported outcomes in patients with a surgically managed unstable ankle fracture, along with comparable infection and re-operation rates. These findings are in the context of selective fixation of PMFs, with only 1 in 10 patients undergoing fixation.