Tibialis Posterior Tendon Entrapment in Posterior Malleolar and Pilon Injuries of the Ankle: A Retrospective Analysis

Abstract

Category: Ankle; Trauma Introduction/Purpose: The Tibialis Posterior tendon (TPT) is the only tendon to come into contact with the distal tibia and is therefore at greatest risk of injury in fractures of the distal tibia. Although TPT injury has been reported rarely with injuries around the ankle they often have been missed and present late. Aim Our aim was to analyse the rate to TPT entrapment in fractures involving the posterior tibia i.e. Pilon (PLM) and posterior malleolar fractures (PMF). Methods: A retrospective analysis of PMF and Pilon fractures over an 8-year period was undertaken. Patients who had undergone surgical fixation of their PMF or PLM were identified from 2014 to 2022, using our prospectively collected database. Any fracture which had undergone a preoperative CT was included. Analysis of their pre-operative CT imaging was utilised to identify TPT entrapment, where if < 50% of the tendon cross section was present in the fracture site this was denoted as a minor entrapment and if ≥50% of the tendon was present in the fracture site was denoted as major. Results: A total of 363 patients were identified for further analysis, 220 who had a PMF and posterior 143 with Pilon injury. The incidence of TPT entrapment was 22% (n = 79) with 64 minor and 15 major entrapments. If the fracture entered the TPT sheath, there was a 45% (72/172) of entrapment as compared to 3.7% (7/190) in fractures not entering the sheath p <.001). There was no significant difference in TPT entrapment in PMF as compared to PML (p=0.353). Conclusion: In our assessment, there was a significant risk of TPT entrapment when the CT images display the fracture line entering the tendon sheath. We recommend that surgeons consider care pre-operative imaging and seek to identify the TPT intraoperatively where entrapment does occur.