Imaging description

The tarsal tunnel is best seen on coronal imaging with advanced cross-sectional imaging such as CT or MRI (Figure 71.1). The tarsal tunnel is superficially bounded by the flexor retinaculum. The flexor retinaculum inserts anteriorly on the medial malleolus, posteriorly on the calcaneal medial tuberosity, distally as a continuation of the plantar fascia, and proximally as a continuation of the superficial and deep aponeuroses of the leg. The deep edge of the tarsal tunnel is bounded by the medial surface of the talus and calcaneus. The tarsal tunnel contains the tibialis posterior tendon, flexor digitorum longus tendon, flexor hallucis longus tendon, and posterior tibial neurovascular bundle. Tarsal tunnel syndrome is caused by compression of the posterior tibial neurovascular bundle within the tarsal tunnel (Figure 71.2).

Importance

Typically, MRI is used to diagnose the cause of tarsal tunnel syndrome. Some of the causes that can be demonstrated by MRI are neoplasms, prominent tenosynovitis, prominent varicose veins, synovial hypertrophy, scar tissue, and ganglion cysts. The cause of the tarsal tunnel syndrome will determine whether the initial treatment of the disease is conservative or surgical. A cause of tarsal tunnel syndrome is demonstrated in approximately 50% of the cases, with the remaining 50% being idiopathic.