Anatomical variations and interconnections of the superior peroneal retinaculum to adjacent lateral ankle structures: a preliminary imaging anatomy study

Aim: This imaging anatomy study aimed at detecting anatomical variations and potential interconnections of the superior peroneal retinaculum to other lateral stabilizing structures. Materials and methods: We retrospectively reviewed the imaging archives of 63 patients (38 females, 25 males, mean age 32.7, range 18–58 years) with available ankle US, MR and CT images to detect whether US and MR can detect the presence of interconnections between the superior peroneal retinaculum and the anterior talofibular ligament, inferior extensor retinaculum and peroneal tendon sheath. We evaluated the presence of common anatomical variations including low peroneus brevis muscle belly, peroneal tubercle, os peroneum, and retromalleolar fibular groove shape in relation to the presence of superior peroneal retinaculum connections. Results: The connections of the superior peroneal retinaculum can be revealed on magnetic resonance imaging (MRI) and ultrasound (US). The connection to the anterior talofibular ligament was located (a) inferior to the lateral malleolus, (b) at the level of the lateral malleolus and (c) on both levels, respectively (a) 49.2% on MRI and 39.7% on US, p <0.05, (b) 44.4% and 58.7%, p <0.05, 36.5% and (c) 27%, p <0.05. Superior peroneal retinaculum–inferior extensor retinaculum (MRI 47.6%, US 28.6% p <0.001) and superior peroneal retinaculum–peroneal tendon sheath (MRI 22.2%, US 25.4% p >0.05) connections were also found both on MR and US. Conclusion: Ankle US and MR revealed interconnections between the superior peroneal retinaculum and the anterior talofibular ligament, inferior extensor retinaculum, and superior peroneal retinaculum. Our results are a starting point for further studies on the connections of the superior peroneal retinaculum and the applicability of ultrasound and MRI in assessing their occurrence. Knowledge of the anatomical connections of the superior peroneal retinaculum may help radiologists with the assessment of lateral ankle injuries, and surgeons with treatment planning.