The Flexor Retinaculum Connects the Surrounding Structures into the Medial Ankle Complex

This study aimed to prove the hypothesis that the medial structures of the ankle are interconnected through the flexor retinaculum’s projections. We conducted a retrospective re-evaluation of 132 MRI examinations of the ankle joint from 57 females and 75 males with an age range of 18–65 and a mean age of 35 years. The correlation between the presence of connections between the flexor retinaculum and the deltoid ligament, the spring ligament, the inferior extensor retinaculum, the paratenon, the fibulotalocalcaneal ligament, the fascia covering the abductor hallucis, and the flexor fibrous sheath were studied. The most common connections of the flexor retinaculum were to the deltoid ligament (97%), the fibulotalocalcaneal ligament (84.1%), and the flexor fibrous sheath (83.3%). Interconnection between the flexor retinaculum and the deltoid ligament correlated with the presence of connections between the flexor retinaculum and the inferior extensor retinaculum, the paratenon, and the spring ligament. Side difference was noticed in connections to the flexor fibrous sheath, the deltoid ligament, the fascia on the abductor hallucis, and the paratenon (p < 0.05). The flexor retinaculum formed a more complex anatomical unit with adjacent structures.