Dorsal Release of the Ankle with Transfer of the Posterior Tibial Tendon in Patients with Paralytic Drop Foot

Objective Realignment of a fixed drop foot to restore gait pattern. Indications Drop foot due to various neurologic disorders (cerebral spastic palsy, traumatic nerve palsy, Charcot-Marie-Tooth disease) with/without dynamic equinovarus deformity and undisturbed function of the posterior tibial muscle-tendon unit. Contraindications Osseous deformities leading to drop foot, degenerative joint disease of the ankle, flexion deformity of the midfoot, scar adhesions around the muscle-tendon unit of the posterior tibial muscle, functional deficits of the posterior tibial muscle, ulcers, or soft-tissue damage. Surgical Technique Prone position: Z-shaped lengthening of the Achilles tendon and open arthrolysis of the posterior ankle and subtalar joint. Supine position: distal tenotomy of the posterior tibial tendon at the navicular. Exposure of the tendon proximally to the medial malleolus. Transposition of the tendon slip along the posterior tibial surface through the interosseous membrane to the distal lower leg. Further rerouting of the tendon beneath the extensor retinaculum to the midfoot. Reinsertion of the posterior tibial tendon to the second or third cuneiform bone. Postoperative Management Immobilization of the ankle in neutral position within a plaster or a walker for 6 weeks,followed by a rigid orthosis and physiotherapy. Results Six patients (mean age 52 years) presented with a neurologic fixed drop foot deformity that had developed more than 8.3 years ago. After 12 months,five patients showed a neutral hindfoot position; one patient exhibited a plantar flexion of 5 degrees. Active dorsiflexion was limited in four patients (MRC [Medical Research Council] 2/5) and not visible in one patient. Total range of motion comprised 20 degrees (active) and 35 degrees (passive). During barefoot walking patients showed a regular swing phase of the concerned leg. Patients estimated the overall result as good or excellent.