Anatomical Landmarks for Locations and Boundary of Distal Tarsal Tunnel at Medial Side of Ankle with Clinical Implication

Abstract

The tarsal tunnel (TT) is an osteofibrous tunnel that separates into proximal and distal tarsal tunnels. The most common nerve entrapment which involved tarsal tunnel was tarsal tunnel syndrome (TTS) which divided into proximal TTS and distal TTS because they had different compression areas and symptoms. We were interested in distal TT because this structure had limited studies. Therefore, we studied anatomical landmarks of locations and boundary of distal TT. We studied forty legs from fresh frozen cadavers and used two reference lines: Malleolar-calcaneal (MC) and navicular-calcaneal (NC) axes. The locations of the distal tarsal tunnel were defined by 10 located points and were recorded in X-coordinate and Y-coordinate. The lengths of boundary of the tarsal tunnel were measured from one point to the other. These results were reported as mean±SD. We found that the distal TT located deep to abductor hallucis (AbH) muscle. Medial wall of distal TT had two layers such as deep fascia of AbH muscle and deep thin layer. It showed the trapezoidal shape and was divided into two tunnels by the septum. The information of the location and boundary of the distal TT could improve knowledge and understanding of clinicians and anatomists. Additionally, this information could help surgeons improve their treatments, especially tarsal tunnel release.