Subtalar joint alignment in ankle osteoarthritis.

Background: Although it has been proposed that in mid-stage ankle osteoarthritis, the subtalar joint can compensate for deformities above the ankle joint, the evidence is weak. We thus investigated subtalar joint alignment in different stages of ankle osteoarthritis using weightbearing computed tomography (CT) scans.

Methods: The subtalar joint of 88 patients with osteoarthritis of the ankle joint and a control group of 27 healthy volunteers were assessed. Subgroups were performed according to the ankle deformity (varus and valgus) and stage of ankle joint osteoarthritis. Subtalar joint alignment was assessed on weightbearing CT scans.

Results: A more valgus subtalar joint alignment was found in patients with varus ankle osteoarthritis. No significant difference of the subtalar joint alignment was evident when comparing different stages of ankle osteoarthritis.

Conclusions: Varus ankles compensate in the subtalar joint for deformities above the ankle joint. Compensation does not correlate with the stage of ankle osteoarthritis.