The ulnar nerve is compressed due to traumatic arthritis of the elbow, and there is a thickened fibrous band between the two heads of the ulnar carpal flexors that compresses the ulnar nerve, called the elbow canal syndrome. Between the medial epicondyle of the humerus and the ulnar eminence, there is an arc-shaped narrow and deep bony sulcus with deep fascia transverse to it, forming a bony fibrous sheath canal, namely the ulnar nerve sulcus, also called the ulnar canal of the elbow. The ulnar nerve and ulnar collateral artery and vein are inside the canal. 1.Etiology Elbow fracture, elbow valgus deformity, ulnar nerve strain or poor fracture repositioning, bone unevenness in the elbow canal, wear and tear on the ulnar nerve; hemangioma, tendon sheath cyst and other occupying lesions in the elbow canal; osteoarthritis, rheumatoid arthritis, systemic disorders such as diabetes, leprosy, etc. can all produce complications of elbow canal syndrome. 2, clinical manifestations Symptoms early patients often feel numbness and discomfort in the little finger. Sometimes they have difficulty writing or using chopsticks. When the symptoms worsen, the ulnar carpal flexors and ring finger and pinky finger deep flexors are weak, the intrinsic hand muscles atrophy, and mild claw-like finger deformities appear. 3.Treatment Conservative treatment is suitable for the early stage of the disease and for those with mild symptoms. The posture of the arm can be adjusted to prevent prolonged hyperflexion of the elbow joint, avoid sleeping on the elbow, and wear elbow protection. Non-steroidal anti-inflammatory and analgesic drugs can occasionally relieve pain and numbness, but steroid hormone closure in the elbow canal is not recommended. Surgical treatment is indicated for intrinsic hand muscle atrophy and poor results of conservative treatment. The ulnar nerve is uncoupled from the ulnar nerve sulcus and moved subcutaneously to the anterior elbow. The ulnar nerve is moved anteriorly with adequate freeing to the distal and proximal ends, and the articular branch of the nerve and one or two muscle branches need to be cut to facilitate displacement to the anterior elbow to prevent intramuscular entrapment after displacement. A piece of deep fascia is lifted at the beginning of the flexor muscle to control the displaced ulnar nerve in the anterior part of the elbow to prevent the displaced nerve from slipping back to its original position when the elbow is extended. The flipped deep fascia should be of a certain width and length to prevent the formation of a new entrapment of the ulnar nerve. Interfascicular release of the nerve bundle is generally not advocated, as it may aggravate the symptoms. Postoperatively, a plaster brace in the flexed elbow position is braked, and practice activities are started after 3 weeks. Other surgical methods are not very popular, although they are also clinically used. 4. Prognosis Preoperative intrinsic hand muscle atrophy is obvious with poor results. The results are good for those who can measure ESP in the elbow before surgery, and poor for those without ESP. Intraoperative degeneration of the intraneural fibers was seen, and the postoperative results were poor. Long duration of symptoms is also a sign of poor prognosis.