Review Question - QID 3107

Subtalar distraction arthrodesis using a bone graft is not indicated in a patient with full ankle dorsiflexion and no tibiotalar impingement.

The radiograph demonstrates post-traumatic subtalar arthritis with deformity. Subtalar arthrodesis in situ would not correct the deformity. Substantial loss of heel height may lead to symptomatic anterior tibiotalar impingement and is considered the most appropriate indication for subtalar distraction arthrodesis. Measurement of the talocalcaneal angle is made using a line representing the long axis of the talus and its intersection with the longitudinal axis of the calcaneus. It is demonstrated in Illustration A. The talar declination angle is formed by the axis of the talus to the plane of support and is demonstrated as angle H in Illustration B. The talocalcaneal height is measured from the dome of the talus to the base of the calcaneus displayed as Line K in Illustration C. Each of these measurements along with longitudinal arch are often decreased in patients with post-traumatic subtalar arthritis and are discussed as deformities that can be corrected with bone block subtalar distraction arthrodesis. Chandler et al and Trnka et al each performed Level 4 studies that concluded that distraction arthrodesis was most appropriate in the setting anterior ankle impingement.