An Update on Posterior Tarsal Tunnel Syndrome

Abstract

Posterior tarsal tunnel syndrome (PTTS) is an entrapment neuropathy due to compression of the tibial nerve or one of its terminal branches within the tarsal tunnel in the medial ankle. The tarsal tunnel is formed by the flexor retinaculum, while the floor is composed of the distal tibia, talus, and calcaneal bones. The tarsal tunnel contains a number of significant structures, including the tendons of 3 muscles as well as the posterior tibial artery, vein, and nerve. Focal compressive neuropathy of PTTS can originate from anything that physically restricts the volume of the tarsal tunnel. The variety of etiologies includes distinct movements of the foot, trauma, vascular disorders, soft tissue inflammation, diabetes mellitus, compression lesions, bony lesions, masses, lower extremity edema, and postoperative injury. Generally, compression of the posterior tibial nerve results in clinical findings consisting of numbness, burning, and painful paresthesia in the heel, medial ankle, and plantar surface of the foot. Diagnosis of PTTS can be made with the presence of a positive Tinel sign in combination with the physical symptoms of pain and numbness along the plantar and medial surfaces of the foot. Initially, patients are treated conservatively unless there are signs of muscle atrophy or motor nerve involvement. Conservative treatment includes activity modification, heat, cryotherapy, non-steroidal anti-inflammatory drugs, corticosteroid injections, opioids, GABA analog medications, tricyclic antidepressants, vitamin B-complex supplements, physical therapy, and custom orthotics. If PTTS is recalcitrant to conservative treatment, standard open surgical decompression of the flexor retinaculum is indicated. In recent years, a number of alternative minimally invasive treatment options have been investigated, but these studies have small sample sizes or were conducted on cadaveric models.