The Supination-Pronation Test for Distal Biceps Tendon Rupture
Prompt diagnosis of a distal biceps tendon complete rupture increases the ability to perform a primary repair and to restore motion and strength. When examining an acute injury, it is important to isolate the biceps brachii tendon from the lacertus fibrosus and the brachialis because the examiner may mistakenly miss a distal tendon rupture by not isolating supination and pronation. The supination-pronation test can be performed easily in the acute setting and confirms attachment of the biceps tendon distally to the bicipital tuberosity of the radius. If the distal biceps tendon is intact, there is substantial change in the shape of the biceps as the arm is supinated (the biceps moves proximally), then pronated (the biceps moves distally). Clinically, the supination-pronation test has been found to be a reliable, pain-free test that should be incorporated in the physical examination to evaluate patients for distal biceps injury.
Conclusion
The supination-pronation test properly isolates the distal biceps tendon and does not cause significant discomfort, which can be a problem with other physical examination tests for acute distal biceps ruptures. The squeeze test involves placing the patient in 60º to 80º of elbow flexion with the forearm pronated. The examiner places 1 hand at the distal myotendinous junction, and the other around the belly of the muscle and squeezes, looking for forearm supination.5 We have not found the squeeze test to be optimal because the amount of forearm supination obtained by performing this test can be subtle. Additionally, the patient commonly has significant ecchymosis and pain associated with this rupture, and it may be too painful to squeeze the muscle belly hard enough to have a reliable test. Another test is the hook test, which is performed by the examiner “hooking” an index finger under the intact biceps tendon from the lateral side.8 Clinically, we have found this test difficult to administer because it requires palpation of the tendon, which is often painful for the patient with an acute injury.
The supination-pronation test can easily be performed in the acute setting, and confirms attachment of the biceps tendon distally to the bicipital tuberosity of the radius. It will not show an incomplete tear, but in that case, the muscle retains its normal length, alleviating the urgency of surgical management. We have found the supination-pronation test to be a reliable and pain-free test that should be incorporated in the physical examination to evaluate patients for distal biceps injury.
