Middle-sized posterior malleolus fractures: Fixed versus non-fixed - A prospective randomized study.

PURPOSE: This study aimed to assess the impact of fixation on functional and radiological outcomes of ankle fractures involving the posterior malleolus. We hypothesized that fixation of the posterior malleolus would be associated with improved radiological and functional outcome.

METHODS: A prospective randomized controlled study was planned and 40 consecutive ankle fractures involving middle-sized (10-25%) posterior fragment were included. Posterior fragments in Group 1 were not fixated while Group 2 underwent posterior malleolus fixation. The patients were evaluated both functionally and radiologically at minimum 2-years.

RESULTS: Demographics and fracture type distributions were similar between the groups. Despite the slightly better functional outcome in Group 2, no significant functional or radiological outcome difference could be detected. Articular step-off> 1 mm was more common in Group 1 (p = 0.04) and the patients with articular step-off showed significantly worse functional outcome in all functional parameters (p < 0.05). Radiological and functional outcome parameters were positively correlated when all patients were evaluated together. Lateral radiographs caused an overestimation in the size of posterior fragment compared to CT (p < 0.001).

CONCLUSION: Although there was a slightly better clinical outcome in patients with fixed posterior fragments, it was not significant at short to mid-term follow-up. However, posterior fragment fixation contributed to functional outcomes by decreasing the incidence of articular step-off> 1 mm, which was found to be a negative prognostic factor.

LEVEL OF EVIDENCE: Level I; prospective randomized controlled study.