Metatarsal tunnel syndrome, also known as tarsal tunnel syndrome or ankle tunnel syndrome, is a series of clinical signs and symptoms caused by the compression of the tibial nerve during its journey through the ankle tunnel located below the posterior aspect of the medial ankle to the plantar aspect of the foot, and was first reported by Keck in 1962. The disease is most common in young adults, those who are engaged in strong physical labor or long-distance runners. 1. Etiology 1. Congenital factors: [adductor hypertrophy and para-[adductor, heel exostosis, flat feet, etc. can reduce the practical volume of the metatarsal canal, thus causing tibial nerve entrapment. Fractures of the heel and ankle: poor repositioning and deformed healing can also reduce the volume of the metatarsal canal. 3. Chronic injury: Those who are engaged in strong physical labor, long-distance runners and frequent high-intensity plantarflexion and dorsiflexion of the ankle joint, tendon sliding increases and friction enhances, which can cause tenosynovitis and tendon sheath congestion and edema, plus the corresponding thickening of the flexor support band, which reduces the stretchability of the metatarsal canal and increases its internal pressure, which can compress the tibial nerve and affect its blood supply, resulting in neurological dysfunction. In addition, patients with rheumatoid arthritis and osteoarthrosis can form hyperplastic bone redundancy, which can also compress the tibial nerve by protruding into the metatarsal canal. 4, internal factors of the metatarsal canal: tendon sheath cysts, lipomas, varicose veins can also cause tibial nerve compression. Clinical manifestations Patients start slowly, mostly on one side. In the early stage, it is manifested as intermittent pain, tightness, swelling and discomfort or numbness in the sole and heel of the foot, and the pain sometimes radiates to the calf, and sometimes there are twitching along the arch of the foot, which is aggravated after prolonged standing or walking, and there is a history of waking up with pain at night. As the disease progresses, the pain is often gradually aggravated, and further sensory loss or disappearance of the innervation area of the tibial nerve in the foot may occur. Skin sensation in the heel may be normal, either because the medial metatarsal nerve splits from the tibial nerve above the metatarsal bone or because the site of entrapment is below the metatarsal canal. In advanced stages, autonomic dysfunction signs such as shiny toe skin, loss of sweat hair, less sweating, and even atrophy of the intrinsic muscles of the foot may appear. The loss of distance discrimination between two points during examination is an important basis for early diagnosis; Tinel’s sign below the back of the inner ankle is often positive; pain can be induced when the foot is externally rotated. Treatment 1.Conservative treatment: In the early stage of the disease, anti-inflammatory and analgesic drugs, rest and closure of the metatarsal canal with prednisolone can be given, and the application of brace to keep the foot inversion position can make the flexor muscle support belt relax and the metatarsal canal become larger and relieve the pain. 2.Surgical treatment: If conservative treatment is ineffective and nerve compression symptoms are obvious, metatarsal canal dissection and decompression can be done.