Anatomical Study And Clinical Application Of The Course Of The Posterior Tibial Nerve At The Ankle

Objective:To investigate the branches, course ,and compression site of the posterior tibia nerve in the foot. Methods:10 adult cadaver feet were dissected by the arc approach below medial malleolus, and the abductor hallucis, were observed. Results:The anatomical characteristics of the abductor hallucis muscle: this muscle originate from the calcaneal tuberosity and navicular, and terminate at the base of the proximal phalange of toe. Unlike the other muscles, tendon of the abductor hallucis muscle, which form a rigid tendon arch in the sole and overlay the medial and lateral plantar nerves, lies under its muscle belly. The medial and lateral plantar tunnels under tendon arch of the abductor hallucis muscle, which was formed by navicular and medial cuneiform bones medially, calcaneus laterally, and plantar square muscle plantarly, were seperated by fibrous septums which originate from the flexor hallucis longus tendon sheath or the calcaneus. The medial and lateral plantar neurovascular bandles were included in the above canals respectively. The calcaneal tunnel strat at the midpoint between the highest point of medial malleolus and calcaneal top posterior to medial malleolus, extend downwardly towords sole, and terminate behind the medial process of calcaneal tuberosity. In the lateral x-ray view, we can visulize a obvious groove-like structure which is regarded as bottum of calcaneal tunnel and content the medial calcaneal nerve. The belly and tendon of the abductor hallucis muscle was measured with 14.018±1.236 and 8.620±0.794 cm in length, 2.620±0.322 and 3.012±0.296 cm in wideness, and 1.492±0.112 and 0.236±0.016 cm in thickness, respectively. The medial and lateral plantar tunnels and the calcaneal tunnel were measured with 4.576±0.412cm, 2.582±0.234cm and 3.028±0.214cm in length, 1.114±0.098cm, 0.964±0.076cm and 1.068±0.086 cm in transver diameter, 0.951±0.082cm, 0.836±0.064cm and 0.654±0.048cm in longitudinal diameter, respectively. Conclusions:This study shown that there exited the medial and lateral plantar tunnels and the calcaneal tunnel anatomically, and the double crush of the tibial nerve main trunk and its branches were put forword. ot only could the tibial nerve be compressed by the flexor retinaculum posterior to medial malleolus, its branches, including the medial and lateral plantar nerve and the medial calcaneal nerve, could also be compressed at the medial and lateral plantar tunnels and calcaneal tunnel, respectively. We considered that the concept of the medial and lateral plantar tunnels and calcaneal tunnel would be extension of traditional tarsal tunnel. The tarsal tunnel syndrome was defined as a series of clinical symptoms which were caused by double crush of tibial nerve main trunk and its branches posterior to medial malleolus and at foot. Except incision of the flexor retinaculum to release the tibial nerve, the medial and lateral plantar tunnels and calcaneal tunnel should also be incised to release the medial and lateral plantar nerve and the medial calcaneal nerve for surgical treatment of the syndrome. 12 cases with tarsal tunnel syndrome were included in this study with an average 1 year follow-up. Those patients were evaluated with the evaluating system based on pain perception which was put forword by Pfeiffer.Except one case with unsatisfactory outcome caused by osteoarthrotis, all the others were relieved from previous sufferings.