Medial subtalar dislocation in an athlete. A case report

Results of closed subtalar dislocations

BACKGROUND

The subtalar dislocation (SD) of the foot is an uncommon injury characterized by a simultaneous dislocation of talocalcaneal and talonavicular joints without involvement of the tibiotalar and calcaneocuboid joints.

PURPOSES

The purpose of this study was to evaluate the clinical and radiological outcome in a consecutive series of close SD.

METHODS

We retrospectively evaluated a case series of patients who presented a close SD. Thirteen patients were selected for this study. There were 9 patients with a medial SD, 3 patients with a lateral dislocation and 1 patient with a posterior subtalar dislocation.

RESULTS

The most frequent symptoms observed in our study included transient mild pain, swelling and decreased ankle ROM, which did not restrict patients' daily activities. However, lower AOFAS scores were observed on patients with associate peritalar osseous injuries.

CONCLUSION

The results of the present study suggest that detecting and treating any associate peritalar fractures are the keys to a successful long-term outcome.

Anatomical considerations of irreducible medial subtalar dislocation

Irreducible medial subtalar dislocation has been associated with the talar head "buttonholing" through the extensor digitorum brevis (EDB) muscle, entrapment of the talar head in the extensor retinaculum, talonavicular impaction, interpositioning of the EDB muscle between the talus and navicular, and buttonholing of the talar head through the talonavicular ligament and joint capsule. Cadaver analysis of the medial subtalar dislocation in this study supported entrapment of the talar head in the extensor retinaculum and talonavicular impaction as well as impingement of the deep peroneal nerve and associated dorsalis pedis arterial branches between the talus and navicular as causes of irreducible subtalar dislocation. In this study, the talar head was not noted to buttonhole through or entrap the EDB muscle. This is the first report of the deep peroneal nerve implicated as a possible cause of irreducible medial subtalar dislocation.