Posterior approaches to the ankle - An analysis of 3 approaches for access to the posterior distal tibia

M.L. Jayatilaka, M. Philpott, C. Gillespie, A. Molloy, L. Mason

Aim: With the increase in the use of CT scanning and fragment specific fixation for complex ankle fractures, utilisation of multiple surgical approaches has increased. Our aim in this study was to analyse three posterior-ankle approaches to find their use and efficacy in accessing the posterior tibia.

Methods: We examined 5 fresh frozen cadaveric lower limbs at the University of Keele anatomy laboratory. Three posterior ankle approaches (posterolateral (PL), posteromedial (PM) and medial posteromedial (MPM) approaches were performed, using a consistent repeatable incision of 7cm. Kirchner wires were then placed parallel to one another at 4 points in the posterior tibia (proximal, distal, medial and lateral). The ankles were imaged using an image intensifier and the distances measured.

Results: The PL approach allowed an average 746.9 mm² diamond of access (DOA) to the posterior tibia (46.2 x16.2mm). The PM approach allowed an average 1101.9mm² DOA to the posterior tibia (56.8x19.4mm). The MPM approach allowed an average of 1184.7mm² DOA to the posterior tibia (55.1x21.5mm). We compared the areas of access for each incision to 149 posterior malleolar fractures on our database. Only 56% of fractures could be fully exposed using the PL incision. In comparison, 78% of fractures could be exposed using the PM incision. Only 19% of patients had posteromedial fractures that could be visualised using the MPM incision, but it did not allow access to the constant posterolateral fragment, thus its usage is primarily as a supplementary 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 fully exposed through the PL approach, and if fixing such fractures the surgeon should be comfortable with multiple approaches.