Posterior Tibial Tendon Transfer for Footdrop

Flaccid footdrop following traumatic injury to the common peroneal nerve or peroneal division of the sciatic nerve

Spastic footdrop seen in cerebral palsy

Other indications may include footdrop associated with poliomyelitis, cerebrovascular accident, Charcot-Marie-Tooth disease, or leprosy

After substantiating the flaccid paralysis of the anterior and lateral compartments, motor examination should focus on strength testing of the posterior tibialis and the gastrocnemius-soleus complex. A prerequisite for posterior tibial tendon transfer is a minimum of four-fifths strength for this posterior musculature.

Evaluate for equinus contracture. Inability to attain at least 10° of passive dorsiflexion with the knee extended will necessitate a heel cord lengthening procedure.

Plain radiographs

• Obtain anteroposterior (AP), lateral, and mortise views of the ankle.

• Obtain AP, lateral, and oblique views of the foot.

• Evaluate for any osseous or articular deformities that may require a concomitant osteotomy or arthrodesis.

Electromyography/nerve conduction studies

• These studies are useful for documenting the level of injury as well as the potential for nerve recovery.

• They are not necessary if the injury was sustained >1 year prior to evaluation and no functional improvement has been observed.

Just proximal to the popliteal fossa, the sciatic nerve divides into the tibial nerve and the common peroneal nerve ( Fig. 74.1A ).

• The tibial nerve provides motor input to the deep and superficial posterior compartments of the leg. Its function is essential to this procedure.

• The common peroneal nerve, including its two terminal branches (the deep and superficial peroneal nerves), provides the motor innervation to the anterior and lateral compartments of the leg. Dysfunction of the common peroneal nerve leads to the development of footdrop.

• The deep peroneal nerve runs between the tibialis anterior and the extensor hallucis longus and must be protected during anterior incisions.

The posterior tibialis muscle arises from the posterior aspect of the interosseous membrane, tibia, and fibula ( Fig. 74.1B ). It travels posterior to the medial malleolus and has a broad insertion into the tuberosity of the navicular bone, all three cuneiforms, and the bases of the second through fourth metatarsals.

Position the patient supine on the operating room table, and apply a tourniquet to the upper thigh.

The leg is exsanguinated using an Esmarch bandage, and the tourniquet is elevated to 300 mmHg.