Peroneal tendon anatomy in the retromalleolar region of the ankle: A new radiological classification

Objectives Lateral ankle pain can be caused by a variety of pathologies, including those involving the peroneal tendons. The spatial arrangement of the peroneal tendons within the trimalleolar groove remains underexplored in the literature. The objective of this study is to propose a new classification to describe and categorize the spatial relationship between the peroneal longus and peroneus brevis (PB) tendons in the retromalleolar groove. Materials and Methods A retrospective analysis of the ankle joint anatomy on magnetic resonance imaging was conducted on 100 consecutive patients undergoing foot and ankle imaging. A musculoskeletal radiologist and orthopedic surgeon meticulously evaluated the spatial relationship between the PB and peroneus longus (PL) tendons in the axial plane and subsequently categorized them as follows: Type 1: PB tendon is deep to PL tendon. Type 2: PB tendon is <50% medial to PL tendon. Type 3: PB tendon is more than 50% medial to PL tendon Type 4: PB tendon adjacent to PL tendon. Descriptive statistics were performed on the cohort and intraclass correlation for interobserver reliability. Results In our study, the most common variant seen was type 1 (40% of cases), followed by type 2. There was good intraobserver reliability with an intraclass correlation of 0.8. Conclusion Our study successfully introduces a novel classification system that effectively delineates and categorizes the spatial relationship between the PB and PL tendons within the retromalleolar groove. This may be of clinical value during tendon repair and reconstruction.