Posterior malleolus fracture: a mid-term follow-up

BACKGROUND: The treatment of posterior malleolar fractures is changing rapidly, and the evidence base is still catching up. This study aimed to assess the mid-term prognosis of posterior malleolar fractures based on different morphological types and provides evidence for the treatment of posterior malleolar fractures. METHODS: We retrospectively analyzed the data of inpatients with posterior malleolar fractures from 1 January 2012 to 31 December 2019 at one high-volume tertiary trauma center. Fracture morphology was classified into small-shell fragment, single-fragment (small-fragment and large-fragment) and multifragment (double-fragment and compressive-fragment) by computed tomography according to our previous study. All patients were followed up at an average of 5.06 (range, 2.21–8.70) years. The Olerud-Molander Ankle Score (OMAS), EuroQol-5 Dimensions (EQ-5D) and American Orthopedic Foot and Ankle Society (AOFAS) score were recorded. RESULTS: Seventy-nine patients were included, and 7 patients were classified into the small-shell group, 52 patients into the single-fragment group and 20 patients into the multifragment group. Of all the patients, the average OMAS, EQ-5D and AOFAS scores were 85.9, 82.8 and 92.5, respectively. In the single-fragment group, patients who underwent surgical fixation in the posterior malleolus had significantly better scores (P = 0.037, 0.033 and 0.027). Among the patients with small fragments, the surgical fixation group also had higher OMAS (93.1 ± 7.5 vs. 83.5 ± 19.5, P = 0.042) and AOFAS scores (98.1 ± 3.1 vs. 91.0 ± 14.1, P = 0.028). The mean OMAS, EQ-5D and AOFAS scores were 85.5, 85.7 and 91.7, respectively, in patients with multiple fragments who underwent surgical fixation. CONCLUSION: This study shows that in fractures with a single fragment, surgical fixation of the posterior malleolar fragment led to a better prognosis in the midterm. All single fragments should be fixed regardless of size. Fixation of the posterior region in all single- and multi-fragments in posterior malleolar fractures led to satisfactory outcomes. LEVEL OF EVIDENCE: Level III, follow-up study.