The tarsus is a bony structure that connects the forefoot to the ankle joint and forms a canal structure below the medial ankle called the ankle canal, which is covered by a flexor support band, through which the posterior tibial muscle, the long toe extensor, the posterior tibial artery, the posterior tibial nerve, and the long bunion muscle pass from anterior to posterior.
Ankle canal syndrome is a syndrome caused by pressure on the posterior tibial nerve or its branches as they pass through the ankle canal, mostly due to excessive pressure or tissue in the ankle canal.
Factors that cause narrowing of the lumen of the ankle canal include.
1. Trauma: distal tibial fracture, post-articular fixation of ankle sprain or crush injury, heel fracture, post-traumatic edema and late fibrosis resulting in adhesion of the posterior cavernous nerve in the ankle canal;
2.Posterior cavernous vein stasis, embolic phlebitis;
3, foot valgus deformity, producing increased tension in the flexor support band and the fiber starting point of the abductor digitorum brevis.
Factors that cause excess tissue in the ankle canal include.
1. tenosynovitis, synovial hyperplasia or tendon sheath cysts of the posterior tibial, flexor hallucis or flexor digitorum brevis tendons;
2. rheumatoid arthritis, synovial tissue edema and inflammation;
3, congenital anatomical abnormalities, such as hyperplasia or hypertrophy of the paraspinatus bunion muscle;
4, Weight gain (excessive fat accumulation);
5, posterior tibial vein aneurysm;
6, Nerve sheath tumor of the tibial nerve and its branches;
7, Tissue hyperplasia in the ankle canal caused by certain drugs.
In some patients, prolonged walking or running and excessive rotation of the anterior ankle joint can cause the posterior tibial nerve to be stretched, irritated, inflammatory reaction, and eventually the manifestation of ankle tube syndrome. This symptom is often bilateral.
Symptoms.
1. Pain (usually burning) that may radiate to the foot, heel or toes; occasionally to the lower leg, but usually not beyond the knee joint;
2, numbness on the bottom of the foot, loss of sensation or loss;
3.Pain when running;
4.Pain when standing for a long time;
5.The pain can be relieved after rest;
6.The pain may increase at night;
7. Pain can be induced by percussion at the posterior ankle canal under the inner ankle, i.e. Tinel’s sign. In severe cases, pain and numbness may appear on the plantar surface of the foot when the foot is turned out or dorsiflexed, or even when the leg is raised straight;
8, pressure pain at the ankle canal, and local lumps or nodules may be palpable.
Diagnosis.
According to the history, symptoms and related physical examination, it is generally not difficult to diagnose, in addition, the following tests are feasible to clarify: tourniquet test: that is, the use of bilateral tourniquet of the calf, inflated to maintain the pressure below the systolic pressure, the affected limb is positive if there is pain and numbness; electromyography: can show the occurrence of lesions in the posterior tibial nerve; imaging: X-ray and CT can show the cause of the bony compression; MRI and MRI and ultrasound can reveal the cause of soft tissue compression.
Treatment.
1, acute phase (pain and inflammation phase) ice;
2. Rest and avoid strenuous exercise;
3.Oral administration of NSAIDs;
4.After the acute period, perform appropriate functional exercises to restore normal joint mobility and muscle strength;
5, glucocorticoid local closed injection;
6.If conservative treatment is ineffective, consider surgical release, mainly to remove the factors causing the compression.