Subtalar dislocation is the simultaneous dislocation of the distal articulations of the talus at both the talocalcaneal and talonavicular joints (perhaps more appropriately called peritalar dislocation). With this injury the tibiotalar joint is undisturbed. Subtalar dislocation can occur in any direction but more commonly medialy (80%) and laterally (rarely anterior or posterior). It typically is caused by falls from a height, MVCs, and severe twisting injuries such as in basketball players who land on an inverted and plantar-flexed foot. Inversion injuries result in medial dislocations and eversion injuries result in lateral dislocations.
Frontal
Lateral
24 yo with fall
Subtalar dislocation is the simultaneous dislocation of the distal articulations of the talus at both the talocalcaneal and talonavicular joints (perhaps more appropriately called peritalar dislocation). With this injury the tibiotalar joint is undisturbed. Subtalar dislocation can occur in any direction but more commonly medialy (80%) and laterally (rarely anterior or posterior). It typically is caused by falls from a height, MVCs, and severe twisting injuries such as in basketball players who land on an inverted and plantar-flexed foot. Inversion injuries result in medial dislocations and eversion injuries result in lateral dislocations. The navicular bone and forefoot are displaced medially with a medial subtalar dislocation and laterally with a lateral dislocation. These dislocations are frequently associated with fractures of the involved bones and a small percentage are open.
Standard AP, lateral and oblique x-rays of the foot are difficult to obtain because of the distortion of the foot and frequently inadequate x-rays are taken leading to a delay/error in diagnosis. AP view shows talonavicular dislocation. In the lateral projection close inspection usually reveals the head of the talus lying superior to the acicular or cuboids in the medial subtalar dislocation, and the taller head appears to be displaced inferiorly in a lateral dislocation.
Suggested reading:
Haapamaki et al. AJR:183, September 2004, 615-622.
S. J. Lawrence and M. Singhal. Open Hindfoot Injuries. J. Am. Acad. Ortho. Surg., June 1, 2007; 15(6): 367 - 376.
Saltzman and Marsh. Hindfoot Dislocations: When Are They Not Benign? J Am Acad Orthop Surg.1997; 5: 192-198.
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