The term “ulnar nerve instability” describes the chronic conditions of subluxation and relocation of the ulnar nerve at the elbow with flexion and extension of the elbow, respectively. Recurrent subluxation of the nerve at the elbow results in a tractional and frictional neuritis and is not to be confused with common compression neuropathy. Ulnar nerve instability without this compression at the cubital tunnel is not common and even more rare is a dislocating nerve. Nevertheless it can be seen during normal dynamic ultrasound imaging for lateral elbow pain.

This pathology may be accompanied by symptoms from the ulnar nerve, such as paraesthesia including pain, burning, tingling, numbness and pins and needles. Further, a niggling inconvenience and a strong pain around the medial humeral epicondyle (inside of the elbow) during manual tasks, upper limb occupational tasks and gym workouts. Tenderness on palpation over the medial humeral epicondyle can be positive and may lead to a possible diagnosis of medial epicondylitis. 

Diagnosis of ulnar nerve instability may be one through exclusion of other conditions or failure of conservative management for another condition. Sometimes the nerve can felt to sublux anteriorly sliding over the medial epicondyle during flexion and then relocating posteriorly during elbow extension.

One clinical test that has been suggested is by stabilising the ulnar nerve with the physiotherapist’s hand by compression on the medial head of the triceps and lateral displacement in elbow extension. This can stabilise the nerve in its proper position and flexion could then be done without any discomfort. On these grounds the authors developed a clinical test that they believe to be diagnostic for the ulnar nerve instability.

Diagnostic test- examiner’s fingers and palm are positioned just proximally to the lateral and the thumb about five centimetres proximally to the medial humeral epicondyle. With the patient’s elbow in extension the ulnar nerve is pressed by the thumb to the medial head of the triceps and both pushed laterally while the lesser fingers apply counterpressure. The nerve is thus stabilised behind the medial epicondyle. Continuous flexion – extension of the elbow then performed should not elicit the symptoms as expected by the patient.

Investigations including plain x-rays, MRI scan and nerve conduction studies can be normal. Often a dynamic ultrasound can reveal the subluxation during elbow flexion.

Conservative management may include strapping, non steroid anti-inflammatory drugs and some physiotherapy-led exercise therapy, but these can prove to be hit and miss, as there may be congenital anatomical anomalies influencing the nerve subluxation. Other than activity modification by ceasing aggravating movements or activities, it will leave surgery as the main option.

Surgical management will then ensue, which may include anterior submuscular transposition of the ulnar nerve combined with minimal epicondylectomy or by anterior subcutaneous transposition of the nerve.