Selective hindfoot arthrodesis for the treatment of adult acquired flatfoot deformity: an in vitro study.

An acquired flatfoot deformity with significant laxity at the transverse tarsal joint was created experimentally and the amount of correction that was obtained with selective hindfoot fusions was measured radiographically. Results showed that the talonavicular, double (talonavicular and calcaneocuboid), and triple arthrodeses were able to fully correct the deformity, including correction of hindfoot valgus with just a talonavicular fusion. Subtalar and calcaneocuboid fusions failed to completely correct the deformity. This study provides experimental evidence that although the triple joints are interconnected, they differ with respect to their ability to malalignment. We conclude that talonavicular or double arthrodesis will correct deformity in a flatfoot with considerable laxity through the transverse tarsal joint, but that a subtalar fusion will not provide consistent correction.