Distal Tendon Biceps Avulsion Diagnosis by Hook Test

When a patient experiences a biceps tendon avulsion, or a tearing away of the biceps tendon, it can be hard for a doctor to diagnose, causing a delay in treatment. The senior author of this study has been diagnosing such avulsions with a test that involves hooking a finger underneath the tendon; the researchers sought to identify if such a hook test was reliable in diagnosing the problem.

Forty-four males and one female, average age 49 years, ranging in age from 25 to 72 years, were studied. Among the patients, 14 patients had been injured with 10 days, five patients between 11 and 21 days, and 26 patients were considered to have chronic injury of over 21 days. Thirty-three patients had complete avulsions, while 12 had a partial avulsion. When the researchers tested the arms of the patients using the hook test, they found a 100 percent rate of abnormality among both groups, those with complete and partial tears. This was compared with the test on the opposite, uninjured arm, which was normal in 100 percent of the cases.

The hook test is done on an arm that is flexed to 90 degrees, with the patient either sitting or standing. The doctor places an index finger on the outside part of the antecubital fossa, or the inside of the elbow, and tries to hook the tendon when bending the finger. If the finger can go hook under the bicep and pull it forward, this is a positive result.

The researchers said, prompt diagnosis of such an injury is important to increase the chances for successful surgical repair. They said that treatment delays of more than two to four months may make such a repair impossible. In this case, a tendon graft may be required, however, the success of tendon grafts is questionable.

References: Shawn W. O'Driscoll, PhD, MD, Lucas. B.J. Goncalves, MD, and Patricio Dietz, MD. The Hook Test for Distal Biceps Tendon Avulsion. In The American Journal of Sports Medicine. November 2007. Vol. 35. No. 11. Pp. 1864-1869.