Plantar pressure distribution after tibiotalar arthrodesis.

Introduction: Arthrodesis is a well-established treatment option for end-stage osteoarthritis of the ankle. Osteoarthritis of the ankle can alter plantar pressure distribution. However, surprisingly little is known about the effect of ankle arthrodesis to alter plantar pressure distribution. The purpose of this study was to determine plantar pressure distribution in a selected group of patients with unilateral arthrodesis of the ankle joint.

Methods: 20 patients with an average age of 60 years who underwent isolated unilateral ankle arthrodesis using a 3-crossed screw technique by a single surgeon were included. After a mean of 25 months (range 12-75 months) post surgery plantar pressure distribution was determined in five regions of the foot. The outcome was evaluated clinically, using the American Orthopaedic Foot and Ankle Society hindfoot score, as well as radiographically. The contralateral normal foot was used as a control.

Findings: Comparing the foot that underwent tibiotalar arthrodesis to the contralateral normal foot, differences were found in the peak pressure and maximum force in the toe region and the lateral midfoot region. In addition, a decrease in the contact time in the forefoot region and a decrease of the contact area in the toe region of the operated foot were identified. The other regions did not show a significant difference. The mean American Orthopaedic Foot and Ankle Society score of the operated leg was 79 (range 46-92) at the last follow up, and the mean fixation angle of the arthrodesis on lateral weight bearing radiographs was 90° (range 86°-100°).

Interpretation: Our results indicate that arthrodesis of the ankle joint can provide high levels of function with minimal changes in the plantar pressure distribution.