Anatomical Features of Patients with Recurrent Dislocation of the Peroneal Tendons

Abstract

Category: Hindfoot; Sports Introduction/Purpose: The occurrence of peroneal tendon dislocation (PTD) may be influenced by anatomical variations in the peroneal muscles and ankle lateral malleolus. One such factor is peroneal groove crowding, which can result from increased muscle and tendons bulk within the peroneal tendon sheath. Another potential factor is the shape of the retromalleolar groove, which determines the inherent stability of the tendons in the groove. This study aims to examine the anatomical variations of the retromalleolar groove and peroneal muscles in patients with and without recurrent PTD (RPTD) using magnetic resonance imaging (MRI) and computed tomography (CT). Methods: This study included 30 patients (30 ankles) with recurrent PTD who underwent both MRI and CT before surgery (PD group) and 30 age- and sex-matched patients (control (CN) group) who underwent MRI and CT. The imaging was reviewed at the level of the tibial plafond (TP level) and the center slice between the TP and the fibula tip (CS level). CT images were used to assess the appearance of a malleolar groove (convex, concave, or flat) and the posterior tilting angle of the fibula. MRI images were used to assess the appearance of accessory peroneal muscles, height of the peroneus brevis muscle belly, and volume of the peroneal muscle and tendons. Low-lying muscle belly (LLMB) of the PB was defined as when the musculotendinous junction extended beyond the tip. The Mann-Whitney U test was used to compare continuous variables, and Fisher’s exact test was used to compare nominal variables. Results: There were no differences in the appearance of the malleolar groove, posterior tilting angle of the fibula, or accessory peroneal muscles at the TP and CS levels between the PD and CN groups. However, the peroneal muscle ratio was significantly higher in the PD group than in the CN group at both levels (both p< 0.001). The peroneal tendons ratio was not significantly different between the groups at both levels. The height of the peroneus brevis muscle belly was significantly lower in the PD group than in the CN group (p=0.001). LLMB of the PB was identified in 19 patients (63.3%) in the PD group and in eight patients (26.7%) in the CN group (p=0.009). Conclusion: The findings of this study suggest that LLMB of the PB and the peroneal muscle ratio are significantly related to RPTD, whereas retromalleolar bony morphology is not. Therefore, maintaining proper volume in the peroneal tunnel is more important than the groove shape. Reduction of the muscle belly of the peroneus brevis during RPTD surgery may help prevent peroneal tendon dislocation.