Introduction: Subtalar dislocation (SD) is an uncommon injury accounting for 1-2% of all dislocations. It involves simultaneous disruption of the talocalcaneal and talonavicular joints, without involvement of the calcaneocuboid or tibiotalar joints or talar neck fracture. We present a retrospective study of pure medial and lateral SDs treated conservatively and discuss the pathogenesis, classification, prognostics and therapeutic aspects of SD.
Materials and methods: Thirty patients, 24 men and 6 women (mean age 33 years; range 18-55) with closed isolated SD were treated conservatively and re-evaluated at 5-12 years. There were 20 medial and 10 lateral dislocations. All patients were managed with immediate closed reduction under general anaesthesia. Open dislocations and SDs associated with fractures were excluded.
Results: The mean AOFAS Ankle-Hindfoot score was 78.8. Seven patients (all with medial SDs) had an AOFAS score of 100; 14 patients (11 with medial and 3 with lateral SD) had a mean AOFAS score of 85; 6 patients (three with medial and three with lateral SD) had a mean AOFAS score of 65; and 3 patients (all with lateral SDs) had a mean AOFAS score of 28. The latter patients subsequently underwent subtalar fusion, with a fair outcome. The mean AOFAS scores of patients with lateral and medial SD were not significantly different (P = 0.05).
Conclusion: Various factors adversely affect outcome, including type of dislocation (lateral/medial, open/closed), severity of the injury, associated fractures, length of immobilization. Management of closed isolated SD is by immediate conservative treatment in order to avoid or reduce the incidence of early soft-tissue and vascular complications and poor long-term outcomes due to post-traumatic arthritis, talus necrosis and subtalar joint stiffness. However, complications may still arise despite correct treatment.