Posterior Approaches to the Ankle: An Analysis of 3 Approaches for Access to the Posterior Distal Tibia

Abstract

Category: Ankle, Trauma Introduction/Purpose: With the increase in the use of CT scanning and fragment specific fixation for complex ankle fractures, utilisation of multiple surgical approaches has increased. The posterolateral approach has been advocated by many, however in our experience, a large proportion of these fractures are not attainable by this approach. Our aim in this study was to analyse three posterior ankle approaches to find their use and efficacy in accessing the posterior tibia in the fixation of posterior malleolar fractures. Methods: We examined 5 fresh frozen cadaveric lower limbs. Three posterior ankle approaches (posterolateral (PL), posteromedial (PM) and medial posteromedial (MPM) approaches were performed, using a consistent repeatable incision of 7 cm extended proximal from the palpable distal extent of the medial malleolus. In both the PL and PM approaches, the flexor hallucis longus (FHL) was taken medially. In the MPM approach, the access was anterior to tibialis posterior (TP). K-wires were then placed parallel to one another at the 4 extremities of the approach. The ankles were imaged using an image intensifier and the distances measured. Our database of 172 consecutively treated posterior malleolar fractures in our department, was used to analyse the fracture fragment size and compare these fracture patterns to the approaches. The fractures were categorised using the Mason and Molloy classification. Only type 2 and 3 fractures were included, leaving 101 in the study. Results: On radiographic analysis, the type 2B and type 3 fractures incorporate 100% and 83% of the posterior width of the tibia respectively. Considering the PL approach only allows access to 40% of the posterior width of the tibia, another approach is required for these fracture patterns. Only 65% of fractures could be adequately exposed using the PL incision. In comparison, 78% of fractures could be exposed using the PM incision. The MPM incision gave the largest area for access to the posterior tibia, however it did not allow access to the constant posterolateral fragment. Only 35% of patients had posteromedial fractures that could be dealt with using the MPM incision, thus its usage is primarily as a supplementary incision, in conjunction with the PL incision. Conclusion: We conclude that the most commonly used approach (the PL approach) gives the least amount of access to the posterior tibia. In comparison to fracture fragment size, almost half of fractures would not be adequately exposed through the PL approach, and if fixing such fractures the surgeon should be comfortable with multiple approaches.