Operative strategy for tri-malleolar ankle fractures with posteromedial plafond involvement: a review of sixty six cases

Abstract

Purpose: We aimed to summarize the radiographic and clinical outcomes in various conditions of tri-malleolar ankle fractures (TMFs) with posteromedial (PM) plafond involvement (TMF + PM) and determine the factors affecting their subjective clinical outcomes.

Methods: Radiographic and clinical findings of 66 patients who underwent operative treatment for TMF + PM were retrospectively reviewed. The patients were classified into three groups according to the PM fracture line location. Type I fractures were defined when the PM fracture line extended medially beyond the PM corner of the distal tibia while type II fractures were those in which the PM fracture line was located laterally to the PM corner. Type III fractures were defined as medial malleolar avulsion fractures when the PM fracture integrated into the medial malleolus. Clinical outcomes were evaluated using a subjective rating scale (excellent, good, fair, poor, and bad). Satisfactory results were defined as excellent, good, and fair. Factors affecting satisfactory clinical outcomes were assessed using a binary logistic regression analysis. Independent variables included demographic, fracture-related, and operation-related factors and radiographic measurements at the final follow-up.

Results: Satisfactory clinical outcomes were observed in 74.2% of the total patients; of these patients, 75.7% (28/37), 76.5% (13/17), and 66.7% (8/12) had type I, type II, and type III fractures, respectively. The binary logistic regression analysis revealed that age at the time of operation, number of incarcerated fragments (IFs), type of IFs, and postoperative articular step-offs (mm) were related to subjective clinical outcomes (all P < 0.05). A positive value for post-operative articular step-offs represented distal migration of the posterior malleolar fragments. The odds ratios for older age, increased numbers of IFs, rotated IFs, and positive articular step-offs were 0.936, 0.116, 0.020, and 0.295, respectively.

Conclusion: Because TMF + PM is highly unstable, a delicate approach is needed according to each patient's fracture condition. Although it is best to reduce the fractured articular surface, a negative step-off, rather than a positive step-off, would be more likely recommended if accurate reduction is impossible. This could be applied to manage IFs, especially when the IFs are rotated. Dimpling of the articular surface induced by the removal of a small IF was not related to unsatisfactory clinical outcomes.

Keywords: Ankle fracture; Articular step-off; Operative treatment; Posteromedial plafond; Three-dimensional computed tomography; Tri-malleolar fracture.