July 2016

Timely and accurate evaluation is imperative for optimal treatment and outcome from rupture of the distal biceps tendon. The mechanism of injury is a sudden eccentric load placed on a flexed elbow. This injury most frequently occurs in males in the fourth to sixth decade of life. Smokers have an increased risk of sustaining this injury, and the use of anabolic steroids and local injection of corticosteroids have been implicated as a cause of the injury.

Patients often report a painful “pop” at the time of injury or a sudden, sharp, tearing sensation in the antecubital fossa that eventually becomes a dull ache. Patients may also exhibit tenderness in the fossa and ecchymosis. Weakness and pain with forearm supination is frequently displayed as well as gross abnormality in the contour of the biceps musculature in comparison with the contralateral side with retraction of the biceps muscle belly. X-rays should be evaluated for bony avulsion of the radial tuberosity. Despite what seems an easy injury to diagnose, delay in accurate diagnosis still occurs.

Multiple tests have been described in the evaluation of the integrity of the distal biceps. O’Driscoll has described the Hook Test in the assessment of anterior pain of the elbow. The arm is actively flexed to 900 with the forearm fully supinated. The examiner then tries to hook the biceps tendon with his/her index finger from lateral to medial (right elbow exam examiner uses his/hers left index finger).

In a normal test, the examiner may hook around the posterior aspect of the biceps tendon and superficial to the brachialis nearly 1cm. The tendon feels like a tight cord. The patient must not forcefully flex the elbow as this allows the bracialis to become firm and thus decrease the space between the biceps tendon and the brachialis.

To evaluate the lacertus fibrosus the examiner comes from the medial side (right index finger to examine right elbow) and may hook the lacertus but the finger does not penetrate as far and the lacertus is more sheet-like.

Performing the exam from both lateral and medial sides is important. An abnormal exam from the lateral side evaluates the integrity of the biceps tendon, the medial side the lacertus fibrosus. If the lacertus is intact, then significant retraction is not likely and primary repair can be expected even in cases of chronic rupture.

The Hook Test may also be used to evaluate partial tears of the distal biceps. Here the Hook Test is performed from lateral to medial and once the tendon is hooked it is pulled on. In a case of a partial tear, pain may be reproduced. At this time additional diagnostic imaging may be warranted.

Further evaluation can be made by observing the contour of the biceps with passive motion of the distal biceps. Here the elbow is placed in 900 of flexion in the neutral position. The forearm is passively pronated and supinated observing the motion of the distal biceps muscle belly. If intact the muscle belly will move proximally with supination and distally with pronation. If completely torn from the radial tuberosity the muscle belly will not move with passive motion.

Submitted by:

Ricardo J. Rodriguez, MD

Baton Rouge Orthopaedic Clinic

Baton Rouge, Louisiana