The Cobb Procedure for Treatment of Acquired Flatfoot Deformity Associated with Stage II Insufficiency of the Posterior Tibial Tendon

Abstract

Background: A supple flatfoot deformity caused by posterior tibial tendon (PTT) dysfunction may include a supination deformity of the forefoot that usually is not sufficiently corrected by the commonly suggested treatment options. The use of a partial anterior tibial tendon (ATT) graft that is rerouted through the first cuneiform to the proximal stump of the PTT may restore plantarflexion power of the first ray (Cobb procedure). Methods: Twenty-two consecutive patients with stage II PTT dysfunction and a supple supination deformity of the forefoot were included. A clinical examination, a subjective score, and the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale were evaluated. Results: The mean AOFAS score increased from preoperatively 53.2 (range 40 to 68) to 88.5 (range 78 to 94) at a followup of 24 (range 12 to 46) months. The overall clinical results were excellent in nine patients (41.0%), good in 12 (54.5%), fair in one (4.5%), and poor in none. None of the patients had decreased power of the anterior tibial tendon compared to the contralateral foot. Nineteen patients (86%) were able to wear shoes without shoe modifications. Conclusions: The Cobb procedure provided satisfactory correction of associated forefoot supination deformity in stage II PTT dysfunction. All patients had improved function because of the increased stability of the first ray. There was no evidence of loss of ATT power. The Cobb procedure may be considered an appropriate alternative to arthrodeses in selected patients with supple supination deformity in flatfeet.