Objective: Treatment of adult instable drop foot by modified Lambrinudi arthrodesis (removal of a wedge between the talus and calcaneus), followed by a posterior tibial tendon transfer to the medial cuneiform in order to provide active dorsiflexion.
Indications: Severe drop foot (of various etiologies) in combination with hindfoot instability. Sufficient function of the posterior tibial muscle.
Contraindications: Neurologic dysfunction of the posterior tibial muscle, infection of foot/hindfoot, Charcot arthropathy, and insufficient patient compliance. RELATIVE CONTRAINDICATIONS: Previous surgery of posterior tibial tendon, critical soft tissues/skin conditions, insufficient neurovascular conditions.
Surgical technique: Lateral skin incision. Debridement of sinus tarsi and removal of the bifurcate ligament to expose the subtalar, calcaneocuboidal, and talonavicular joints. Resection of a bone wedge from the calcaneus and talus (25-30°) to correct the drop foot deformity. Cartilage removal from the calcaneocuboid joint. Debridement of both the talar head and the navicular to allow adequate fitting. After reduction (neutral dorsiflexion and 10° foot abduction), preliminary fixation with Kirschner wires. Final fixation with canulated screws (talonavicular, calcaneocuboidal, and subtalar joints). Medial skin incision at the navicular tuberositas to deattach the posterior tibial tendon with a bony fragment. The tendon stump is harvested 10 cm proximal to the tibiotalar joint. Small skin incision at the anterolateral aspect of the distal lower leg. The posterior tibial tendon is transferred through the interosseous membrane and reattached to the medial cuneiform with a screw.
Postoperative management: Immobilization with a removable short leg cast for 2-4 days. Ambulation with full weightbearing in a cast for 8 weeks. Radiographic assessment 8 weeks postoperatively. After bony healing, mobilization in normal shoes is allowed. Intensive physiotherapy to train the dorsiflexion.
Results: The average correction of drop foot deformity was 18.7°. Active dorsiflexion increased significantly from 30° preoperatively to 10° postoperatively.