Cubital Tunnel Release

Cubital tunnel release is a surgical procedure that relieves pressure on the ulnar nerve at the elbow, addressing numbness and weakness in the ring and little fingers.

The ulnar nerve passes behind the medial epicondyle of the elbow through the cubital tunnel, a space that narrows as the elbow bends. Compression there causes numbness in the little and ring fingers, weakness of grip and pinch, and eventually wasting of the small muscles of the hand. It is the second commonest compression neuropathy in the upper limb. Release divides the structures compressing the nerve; where the nerve is unstable and snaps over the epicondyle afterwards, it is moved in front of it.

Patients with cubital tunnel syndrome that has not settled with activity modification, avoidance of sustained elbow flexion and night splinting in extension. Surgery is indicated earlier where numbness is constant, where there is weakness of pinch or grip, where there is clawing or visible wasting of the first dorsal interosseous muscle, or where nerve conduction studies show significant conduction block — all indicate damage that will not reverse with continued compression. Where symptoms are intermittent and there is no objective weakness, non-operative treatment is reasonable and often effective. Elbow arthritis, previous fracture or a subluxating nerve influence which procedure is chosen.

A day case under regional or general anaesthesia, taking around thirty to sixty minutes. In a simple in-situ decompression an incision is made behind the medial epicondyle and the nerve is released through Osborne's ligament, the fascia of flexor carpi ulnaris and any proximal fascial bands, leaving the nerve in its bed. The elbow is then flexed and extended to check the nerve does not dislocate. Where it does, or where there is a bony abnormality or previous trauma, the nerve is transposed anteriorly and placed either subcutaneously or beneath a muscle layer, with care to release every point of tension along its new course, since an incompletely mobilised transposed nerve is worse than one left alone. The medial antebrachial cutaneous nerve branches are protected throughout.

Elbow movement starts within days after in-situ decompression and after a short protected period following transposition. Sutures are removed at ten to fourteen days. Intermittent tingling often settles within the first weeks. Constant numbness and weakness recover slowly over six to twelve months as the nerve regenerates, and intrinsic muscle strength is the last thing to return; where wasting was established it may not return fully. Light activity resumes within days, driving at one to two weeks, and heavy manual work at six weeks. Hand therapy is used for nerve gliding and, where the intrinsic muscles are weak, for grip and pinch retraining.

Numbness over the inner forearm and elbow from injury to the medial antebrachial cutaneous nerve is the commonest specific complication and can leave a persistent numb patch or tender neuroma. Elbow stiffness, infection and haematoma occur. Persistent or recurrent symptoms follow incomplete release, a second site of compression, or perineural scarring, and revision surgery for a failed cubital tunnel release is less predictable than the primary operation. After transposition the nerve can become tethered or kinked at a point of incomplete mobilisation. Results are good where surgery is done before muscle wasting develops and markedly less predictable once it has, which is the main reason not to wait.