Subtalar arthrodesis for posterior tibial tendon dysfunction and pes planus.

Twenty-one patients (21 feet in 18 women and three men) who were treated with subtalar arthrodesis for posterior tibial tendon dysfunction and pes planus at an average age of 60 years (range, 44-75 years) were studied. Mean duration of symptoms was 3 years. All had realignment of the calcaneus in relation to the talus, and all had screw fixation without supplemental bone graft. Average followup was 3 years (range, 2-5 years). All patients had successful union. The tibiocalcaneal angle averaged 13 degrees +/- 3.1 degrees before operation and 6 degrees +/- 1.9 degrees after operation. The lateral talometatarsal, lateral talocalcaneal, and lateral tibiotalar angles all improved significantly. Arch height (navicular height) increase averaged 5 +/- 2.7 mm. Arch length (calcaneal-metatarsal) decrease averaged 4 +/- 3.2 mm. One complication occurred: delayed wound healing (excellent result). Clinical results were excellent in eight feet, good in eight, fair in four, and poor in one. Patients were satisfied with the operative result in 16 feet, satisfied with reservations in four, and dissatisfied with the operative results in one. Subtalar arthrodesis effectively corrects deformity, does not require bone graft, has a high union rate, and is associated with a low complication rate. However, 11 of the 21 patients continued to have some pain, and in patients with preexisting arthrosis of adjacent joints, symptoms may persist.