ObjectiveTo investigate the effectiveness of tibialis posterior tendon transfer for foot drop secondary to peroneal nerve palsy.MethodsThe clinical data of 21 patients with unilateral foot drop secondary to peroneal nerve palsy between October 2009 and September 2016 was retrospectively analyzed. There were 12 males and 9 females with an average age of 32.1 years (range, 23-47 years). The causes of peroneal nerve injury were iatrogenic injury in 7 cases, tibiofibular fractures combined with compartment syndrome in 5 cases, nerve exploration surgery after stab or cut injury in 3 cases, direct violence in 4 cases, and the fibular head fracture in 2 cases. The average time from injury to operation was 5.6 years (range, 2-8 years). There was 1 case of hallux valgus and 5 cases of toe flexion contracture. The American Orthopaedic Foot and Ankle Society (AOFAS) ankle and hindfoot scores, Foot and Ankle Ability Measure (FAAM) scores, range of motion (ROM), and dorsiflexion strength of ankle joint were used to evaluated the ankle function. Radiographic evaluation for the changes of postoperative foot alignment included Meary angle, calcaneal pitch angle, and hindfoot alignment angle.ResultsAll incisions healed by first intention. All patients were followed up 18-42 months (mean, 30.2 months). The dorsiflexion strength of ankle joint recovered from grade 0 to grade 3-4 after operation. There was no patient with a postoperative flat foot deformity and claw toe during follow-up. There was no significant difference in Meary angle, calcaneal pitch angle, and hindfoot alignment angle between pre- and post-operation (P>0.05). The AOFAS score, FAAM score, and ROM of dorsiflexion significantly improved at last follow-up when compared with preoperative values (P<0.05); while there was no significant difference in ROM of plantar-flexion between pre- and post-operation (t=4.239, P=0.158). There were significant differences in AOFAS score, FAAM score, and ROM of dorsiflexion between affected and healthy sides (P<0.05); but no significant difference in ROM of plantar-flexion was found (t=2.319, P=0.538).ConclusionTibialis posterior tendon transfer is an effective surgical option for foot drop secondary to peroneal nerve palsy. And no postoperative flat foot deformity occurred at short-term follow-up.