An unconstrained cadaver ankle model was designed to reevaluate the effect of ankle mortise widening and syndesmotic fixation on the load-bearing characteristics of the tibiotalar joint. Tibiotalar contact area, centroid shift, and mean contact pressure were quantified using a pressure-sensitive film technique. Six fresh-frozen below-knee amputation specimens were axially loaded with 500 N in three positions: neutral, 10 degrees of dorsiflexion, and 20 degrees of plantarflexion. The tibiotalar contact area and centroid position for each specimen in its intact state were first determined and then compared with values obtained after syndesmotic fixation, mortise widening of 2 and 4 mm, and deep deltoid ligament transection. Syndesmotic fixation significantly decreased joint contact area but did not consistently affect centroid position. However, unlike earlier studies, which used more constrained ankle fracture models, mortise widening with or without deltoid rupture was not found to significantly affect contact area, centroid position, or joint contact pressure. When statically loaded, the talus moved to its position of maximal congruence in the mortise, rather than displacing laterally along with the lateral malleolus.

Deltoid ligament forces were studied after observing deltoid ligament insufficiency in several post-triple arthrodesis patients. Six fresh-frozen, below-knee amputation specimens were axially loaded. The results demonstrate that a properly positioned triple arthrodesis produced deltoid ligament forces that were similar to those seen with an intact tibialis posterior tendon. A triple arthrodesis in combination with a lateral displacement calcaneal osteotomy produced deltoid ligament forces that were 76% greater than those seen with the intact tibialis posterior tendon (P < .05). A triple arthrodesis in combination with a medial displacement calcaneal osteotomy produced deltoid ligament forces that were 56% less than those seen with the lateral displacement calcaneal osteotomy (P < .01). Patients with longstanding ruptures of the tibialis posterior tendon and associated peritalar subluxation/dislocation may have less than optimal clinical results after triple arthrodesis, unless the hindfoot can be properly reduced, due to persistent elevated forces in the deltoid ligament and resulting ligament laxity. This study suggests that a medial displacement calcaneal osteotomy in combination with a triple arthrodesis may be a viable treatment when the hindfoot cannot be positioned properly.

This article describes a patient with a 10-year history of persistent ankle pain. Differential diagnosis included osteoid osteoma and anterior ankle impingement. This patient subsequently underwent arthroscopic excision of a lesion on the talar neck following a complete radiographic work-up, which was nondiagnostic. The diagnosis of osteoid osteoma was finalized upon pathologic study of the arthroscopic shavings. The use of a motorized instrument for excision did not preclude pathologic evaluation of the specimen. Therefore, in an accessible location on the talar neck, arthroscopic excision of an osteoid osteoma can be performed.