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A 50-year-old man presents with right arm pain, weakness, and bruising after an injury 3 days earlier. He was lifting a heavy object off the ground when he felt a pop in his elbow “like something snapped.” On examination, ecchymosis is noted along the medial arm and antecubital. A positive “hook test” and weakness with resisted forearm supination is also noted.
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The distal biceps tendon originates from the biceps muscle, which is the most superficial muscle of the anterior arm, courses deep to the antecubital fossa, and inserts on the radial tuberosity. The biceps is the primary forearm supinator and also assists the brachialis with elbow flexion.
Biceps tendon ruptures generally occur in the dominant hand when trying to lift an object from elbow extension to flexion. The average age of injury is 50 years and generally, distal biceps tears only occur in men. A palpable defect, or positive hook test, should be noted at the antecubital fossa with complete distal biceps tendon tears. A hook test is performed by asking the patient to actively flex and maximally supinate the forearm while the examiner uses an index finger to try and hook the lateral edge of the biceps tendon. An absent biceps tendon that cannot be hooked is a positive test for a complete rupture. A palpable distal biceps tendon after injury can indicate a partial tear. It is important to examine the contralateral arm to feel for a palpable difference. A significant loss of supination strength and a moderate to mild loss of arm flexion strength is usually noted after a distal biceps tendon tear.
If the patient has a positive hook test with classic signs and symptoms, then a complete rupture can be presumed. Magnetic resonance imaging (MRI) is only indicated if a partial tear is suspected or cannot be ruled out. Otherwise, complete distal biceps tendon ruptures should be treated with surgical repair. Without repair, patients will lose 40% to 50% supination strength, 30% flexion strength, and 15% grip strength. Patients may also get activity-related arm pain and deformity with nonoperative treatment. Excluding sedentary elderly patients, all others should have a tendon repair. Surgical repair should occur within 2 weeks of the injury to avoid tendon retraction and more extensive surgery.
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
References
- Ramsey ML. Distal biceps tendon injuries: diagnosis and management. J Am Acad Orthop Surg. 1999;7(3):199-207.
- Dold A, Stern J. Distal biceps avulsion. Orthobullets website. http://www.orthobullets.com/sports/3081/distal-biceps-avulsion. Updated June 23, 2016. Accessed August 2, 2016.
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