NEW TENDON TRANSFER FOR CORRECTION OF DROP-FOOT IN COMMON PERONEAL NERVE PALSY

Abstract

Common peroneal nerve (CPN) palsy has been reported to be the most frequent lower extremity palsy characterized by a supinated equinovarus foot deformity and foot drop. Dynamic tendon transposition represents the gold standard for surgical restoration of dorsiflexion of a permanently paralyzed foot. Between 1998 and 2005, we operated on 16 patients with traumatic complete CPN palsy.

An osseous tunnel is drilled from anterior tibialis tendon (ATT) bony insertion through the cuneiform bones in the direction of the third cuneiform, through which the ATT is extracted and then pulled proximally under the extensor retinaculum. New ATT origin on the third cuneiform is therefore created. A double tendon transfer is then performed with a direct tendon-to-tendon suture at the distal third of the leg between the rerouted ATT and the posterior tibialis tendon (PTT) (transposed anteriorly through interosseous membrane) and between the flexor digitorum longus tendon (FDL), similarly transposed and sutured side-to-side with the extensor digitorum longus and extensor hallucis longus tendons. This second transfer strengthens ankle dorsiflexion and reanimates toe extension.

All 16 patients were reviewed at a minimum followup of 24 months. Results were assessed using the Stanmore system questionnaire and were classified as excellent in eight, good in five, fair in two, and poor in one. In all cases, transosseous rerouting of the ATT provided a sufficient tendon length, which permitted tendon-to-tendon suturing between the ATT and PTT to be performed proximal to the extensor retinaculum eliminating tendon length-related problems. The new origin of the ATT at the third cuneiform was confirmed to be the optimal traction line to achieve maximum dorsiflexion with minimal imbalance in accompanying pronation and supination. Double tendon transfer also avoids not only drop of the toes, but also allows some extension of the hallucis. Postoperative static and dynamic baropodometric evaluations also were performed showing an overall satisfying progression of gait characterized by the absence of external overload in toe plantar flexion and by reduction of foot contact time with the ground with improvement of heel contact and pushoff phase with evidence of a longer step.

The novelty of our proposed technique is that of moving the insertion of the recipient tendon (ATT) toward the donor transferred tendon (PTT) and not the contrary, providing an appropriate direction of pull with adequate length and fixation. For treatment of complete CPN palsy, transosseous rerouting to the third cuneiform of the ATT and dual transfer of the PTT and FDL tendons is a reliable method to restore balanced foot and toe dorsiflexion producing a normal gait without the need for orthoses