Changes in gait associated with acute stage II posterior tibial tendon dysfunction S.I. Ringleb, S.J. Kavros, B.R. Kotajarvi, D.K. Hansen, H.B. Kitaoka, K.R. Kaufman * Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, United States Received 19 December 2005; received in revised form 2 June 2006; accepted 18 June 2006 Abstract The purpose of this study was to examine differences in gait mechanics between patients with acute stage II PTTD and healthy volunteers. Hindfoot and midfoot kinematics, plantar foot pressures and electromyographic (EMG) activity of the posterior tibialis, gastrocnemius, anterior tibialis and the peroneals were measured in five patients with acute stage II PTTD. Kinematics and kinetics were compared to a database of 20 healthy volunteers. EMG and plantar pressure data were obtained from five healthy volunteers. Hindfoot moments and powers were also calculated. The center of pressure excursion index (CPEI) was calculated from the plantar pressures. Significant differences were observed between the two groups, which confirmed clinical observations. Limited hindfoot eversion and increased midfoot external rotation occurred during the first and third rockers. The EMG data suggested that tendon dysfunction in the posterior tibialis is associated with compensatory activity, not only in its antagonists (the peroneals), but also in the anterior tibialis and the gastrocnemius. These data suggest that non-operative treatment of patients with PTTD should consider minimizing the activity of the posterior tibialis as well as the peroneals, the anterior tibialis and the gastrocnemius. # 2006 Elsevier B.V. All rights reserved. Keywords: Posterior tibial tendon dysfunction; Flatfoot deformity; Gait; Plantar pressure; EMG 1. Introduction Posterior tibial tendon dysfunction (PTTD) is the most common cause of adult acquired flatfoot deformity. This dysfunction typically begins with a paratenonitis of the tendon which may lead to synovitis, intrasubstance tearing and tendinosis. A total rupture of the tendon is possible, however, not prevalent. In the early stages of PTTD, the hindfoot is flexible. As the pathologic process progresses, the hindfoot becomes rigid, and the subtalar, midfoot and tibiotalar joints may develop arthritis. PTTD is usually characterized into four stages. Patients presenting with stage I PTTD exhibit paratenonitis with pain over the posterior tibial tendon (PTT), typically just posterior and inferior to the medial malleolus. There is generally no loss of strength, radiographs are usually normal and the hindfoot is flexible. In stage II PTTD, the PTT elongates and intrasubstance tears develop, leading to a unilateral flexible flatfoot deformity [1]. Patients typically cannot perform the ‘‘single heel rise test’’ in the affected limb and degenerative arthritis of the hindfoot may develop. In stage III PTTD, the hindfoot is rigid and degenerative arthritis can be advanced in the subtalar and midfoot joints. Further postural changes take place, which include a varus forefoot and calcaneofibular impingement [1]. Stage IV PTTD includes the rigid hindfoot with the addition of a valgus talus in the ankle mortise. This is thought to lead to degenerative arthritis at the tibiotalar joint [2]. Despite the wealth of information on the classification and operative [2–10] and non-operative [2,11–13] treat- ment of patients with PTTD, there are few studies examining the effects of PTTD on gait [14–16]. Changes in step length, cadence, velocity and maximum sagittal www.elsevier.com/locate/gaitpost Gait & Posture 25 (2007) 555–564 * Corresponding author. Tel.: +1 507 284 2262; fax: +1 507 266 2227. E-mail address: Kaufman.kenton@mayo.edu (K.R. Kaufman). 0966-6362/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.gaitpost.2006.06.008