Comparison of four posterior approaches of the ankle: A cadaveric study

The purpose of this study is to provide a detailed comparison of 4 posterior approaches of the ankle: the posteromedial, modified posteromedial (mPM), Achilles tendon-splitting (TS), and posterolateral approaches.

Cadaveric dissections were performed to assess the influence of the medial and lateral retraction forces on the neuro-vascular bundle with suspension scales and to measure the medial and lateral exposed areas of the posterior tibia and talus. Data was acquired with the ankle in neutral position and in plantar flexion.

Both the mPM and TS approaches provided excellent visualization of the posterior tibia with the ankle in plantar flexion (16.6 cm² and 16.2 cm², respectively). The medial aspect of the posterior tibia, however, was significantly better exposed in the mPM approach than in the TS approach with the ankle in neutral position (8.9 cm² vs 6.5 cm²). The lower value for medial retraction force in the mPM approach (1.9 N in neutral position and 0.9 N in plantar flexion) indicated a lower risk of injury to the neuro-vascular bundle (the tibial nerve and the posterior tibial artery). The posterior talus, however, is best visualized through the TS approach with the ankle in neutral position (4.5 cm²).

The current study demonstrated the usefulness of the mPM approach. When internal fixation of the fibula is unnecessary, the mPM approach is preferable, considering the potential damage to the Achilles tendon associated with the TS approach.