Peroneal Sheath Volumes in Patients with Peroneal Tendon Injuries

Abstract

Category: Sports Introduction/Purpose: Peroneal tendinopathy is a common condition of the ankle and may lead to substantial pain and disability. Low lying peroneus brevis (PB) muscle belly, accessory tendons and bony abnormalities have been implicated in peroneal tendon pathology. To date, studies have reported the presence of these variants or the distal extent of a muscle belly with the presumption that this reflects an increased intra-sheath volume. The goal of this study was to perform volumetric measurements of MR images of peroneal tendons in patients with peroneal pathology requiring surgical intervention and those without. Methods: Two fellowship trained musculoskeletal radiologists evaluated MR images of patients with and without peroneal tendon pathology. The volume of the peroneal tendon sheath and its contents were measured from the level of the tibial plafond down to the peroneal tubercle. The volumes were measured using the Vital Images 3D Vitoria program. The program allows calculation of volumes based on selected area outlines on each axial slice and then compiles each slice into a stacked volume. The presence of a peroneus quartus (PQ), synovitis and peroneal tendon tears were also recorded. Results: Fifty-one patients with peroneal pathology and 15 control patients were included. The mean distance of the PB muscle belly to the tip of the fibula was 5.55 ± 2.5 mm and 11.79 ± 4.07 mm for the groups with and without pathology, respectively (p=0.017). The mean total sheath volume was 7.06 ± 0.95 cc and 5.12 ± 0.53 cc (p=0.001), respectively. The mean PB and PQ combined volume was 1.31 ± 0.29 and 0.86 ± 0.24 cc (p=0.023), respectively. In isolation, the peroneal muscle volume was 0.87 ± 0.25 cc and 0.80 ± 0.25 cc (p=0.733), respectively. Conclusion: The volume of the peroneal tendon sheath and its contents are greater in the patients with peroneal tendinopathy that required surgery compared to controls. Despite the lower position of the muscle belly in the peroneal tendinopathy group, which is similar to previous studies, this was not reflected in increased volumetric measurements. However, when the PQ tendon was included this combined volume was significantly greater. Volumetric measurements are a more accurate way to assess the peroneal sheath in patients with peroneal pathology.