Midfoot injuries

Last evidence check May 2011

Subtalar dislocations are rare, accounting for only 1% of dislocations. They are classified according to the direction in which the calcaneum is dislocated. Medial dislocations are three times commoner than lateral. However lateral dislocation is commoner in high-energy injuries and open injuries, and lateral dislocations are more likely to need open reduction. 2-3% are dislocated anteriorly or posteriorly. Seven of 23 patients in Jungbluth's (2010) series were open, all of which were irreducible. Menetrey and Fritschy (1999) reported a syndrome of posterior subluxation of the subtalar joint in ballet dancers landing on demi-pointe.

Subtalar dislocations have a high incidence of associated fractures: Bibbo et al (2001) identified additional injuries in all of 9 patients who had CT post reduction, 4 of which altered management. The commonest injuries are:

In addition there may be injuries to the surrounding soft tissues. The classical soft tissue injury is tearing of the flexor retinaculum in a lateral dislocation, leading to displacement of the tibialis posterior tendon into the dislocation, blocking reduction. Ligament, nerve and vessel injuries are all recognised.

Clinical features

Complex, open, irreducible subtalar dislocations are usually caused by high energy trauma such as road accidents. However, minor trips, falls and sports injuries can dislocate the subtalar joint.

The diagnosis may be obvious from the deformity of the hindfoot. However, it may be confused with an ankle fracture, or obscured by swelling or other injuries. The hindfoot should be specifically examined during the secondary survey in the polytrauma patient.


Most dislocations can be reduced closed, including probably 90% or more of low-energy injuries. Lateral dislocations are more often irreducible, usually because the posterior tibial tendon becomes entrapped (Waldrop et al 1992). Irreducible medial dislocations usually occur because the talar head buttonholes through the capsule, extenson retinaculum or extensor digitorum brevis muscle (although the latter was not found in Heck’s (1996) study. Open reduction through an appropriate longitudinal approach is carried out. Some dislocations remain unstable after reduction and can be stabilised with percutaneous wires or an external fixator (all dislocations that required open reduction in Jungbluth's (2010) series had external fixation as well as one which was unstable after closed reduction). Otherwise a below-knee cast is used – 4 weeks NWB appears the commonest practice in published studies, followed by resumption of movement and weightbearing out of cast.

Jungbluth (2010) reported a mean AOFAS score of 82.4/100, and there was no difference between patients who had had an external fixator or a cast, or related to the direction of dislocation. Eighteen patients were pain-free, the mean time off work was 10.3 weeks and all patients who did sports before injury were able to return.

In view of Bibbo’s (2003) study, we would recommend a CT after reduction as additional surgery may be required for associated fractures, especially after lateral dislocations.


Not surprisingly, the severity of the original injury appears to be the main determinant of outcome. 75-80% of patients with low-energy injuries do well, although most have some restriction of movement and subtalar OA. In high-energy injuries, almost all have some OA although it may be symptomatic in only 30-60% (Goldner 1995, Bibbo 2003). In the most severe open injuries (Goldner 1995), 1/3 had avascular necrosis of the talus, half had had a subtalar fusion and only 1/3 returned to work.