To investigate the early effect of modified posterior tibialis muscle transfer in treating foot drop and varus deformity caused by common peroneal nerve injury.

A retrospective case series study was conducted to analyze the clinical data of 6 patients with foot drop of common peroneal nerve palsy and varus deformity admitted to Beijing Jishuitan Hospital from December 2017 to October 2019, including 4 males and 2 females, aged 33-48 years [(39.5±6.0)years]. The left side was involved in 4 patients and the right side in 2 patients. All patients underwent posterior tibial muscle transfer. The insertion of posterior tibial muscle was reconstructed in the fourth metatarsal with the tendon allograft to correct foot drop and varus deformity. The range of motion of active ankle dorsiflexion and plantar flexion and range of motion of varus and valgus of foot were measured before operation and at the last follow-up. The isokinetic torque peak value of ankle dorsiflexion and plantar flexion at 60°/s angular velocity and peak isokinetic torque of foot varus and valgus at 60°/s angular velocity were measured before operation and at the last follow-up. The postoperative foot imaging evaluation was performed at the last follow-up, including Meary angle, calcaneal projection and diameter of the fourth metatarsal. The American Orthopaedic Foot & Ankle Association (AOFAS) ankle-hindfoot score was used to evaluate the ankle function.

All patients were followed up for 6-17 months [10(6, 15)months]. At the last follow-up, the range of motion of dorsiflexion of the ankle [6(0, 10)°] and foot valgus [3(0, 5)°] were significantly improved compared with the preoperative level [-31(-33, -28)°, -10(-12, -8)°] (P<0.05); the ankle dorsiflexion torque [(7.7±0.8)Nm] and foot valgus torque [(7.2±0.7)Nm] were significantly improved compared with the preoperative level [(0.0±0.0)Nm, (2.1±0.6)Nm]at 60°/s angular velocity (P<0.01). Imaging examination showed no acquired flat foot deformity and deformation of the fourth metatarsal insertion. The AOFAS ankle-hindfoot score increased from 50-73 points [(61.3±8.4)points] before operation to 75-97 points [(86.8±7.2)points] at the last follow-up (P<0.01).

For foot drop and varus caused by common peroneal nerve injury, modified posterior tibialis muscle transfer can increase the torque of ankle dorsiflexion and valgus, improve the ankle range of motion, and accelerate the ankle function recovery.

Peroneal nerve; Transplantation, heterologous; Foot drop