Popeye’s Peril: The Biceps Blowout
Author: Katherine Boehm, DO
Peer-Reviewer: Kareem Shahin, DO
Final Editor: Noopur Basu, MD; Alex Tomesch, MD, CAQ-SM
A 38 year male with no significant past medical history presents for right elbow pain after a skydiving injury. He states that while he was trying to adjust his chute, a gust of wind caught his chute and his arm was jerked straight and he thinks he heard a pop. He has pain and weakness with opening jars. He denies numbness or tingling. On exam his arm appears like Image 1. He has ecchymosis on the medial aspect of his arm. Motor strength reveals 4 / 5 flexion and 3 /5 supination with pain. When his arm is flexed to 90 and he supinates against resistance, there is no cord-like structure on palpation. Radiographic imaging is normal.
Image 1: Physical exam appearance of your patient. Photograph courtesy of Wikimedia commons.
What is the diagnosis?
The patient has a distal biceps tendon rupture. He likely has a full tendon rupture given the positive Hook test (test detailed below). Rupture of the distal aspect of the biceps tendon is rare, reported to be only 10% of biceps tendon ruptures [1]. Some known risk factors include anabolic steroid use, smoking, compromise of tendon integrity such as intrinsic degeneration, hypovascularity, and mechanical impingement [1].
What is the mechanism of injury?
Both heads of the biceps muscle tendons insert onto the radial tuberosity and the major function of the muscle is forearm supination and elbow flexion. The mechanism of injury for a biceps tendon rupture is excessive eccentric tension as the elbow is forced from a flexed to extended position. This is classically presented as catching a heavy falling object.
What are the expected physical exam findings?
The patient usually will have ecchymosis and tenderness to palpation at the antecubital fossa as well as pain with strength testing in flexion and supination. The pathognomonic Popeye sign is seen in proximal biceps tendon rupture however there is a Reverse Popeye sign for distal biceps tendon ruptures.
There are 2 special exams used to test for distal biceps tendon ruptures.The first test is the Hook test, in which the examiner attempts to “hook” the tendon when moving laterally to medially on the patient’s arm as they are actively flexing the elbow. If the examiner is able to “hook” the tendon, then it is not torn. This is demonstrated here.
The second test is the biceps squeeze test. The patient rests with the forearm pronated and elbow flexed to about 70 degrees to isolate the biceps brachii. The examiner then squeezes the biceps muscle around the muscle belly, which should cause the forearm to supinate . If there is no supination, this can indicate a complete rupture of the tendon. This is demonstrated here.
What imaging should you get?
Distal biceps tendon rupture is usually a clinical diagnosis, however you can obtain radiographs to rule out bony injuries. Coronoid fracture can mimic distal biceps rupture and there is a small risk of bony avulsion of radial tuberosity with biceps tendon ruptures. Point of care ultrasound can confirm the diagnosis, however MRI is considered the gold standard as it can show partial tears as well as measure tendon retraction [4].
What is the management in an urgent setting? When do you consult orthopedic surgery?
Nonoperative treatment consists of physical therapy and supportive care and is a good option for patients that have low demand or are willing to lose some level of function, such as older or sedentary patients. Nonoperative treatment can lead to loss of strength in supination (40%), flexion (30%), and grip strength (15%) [1].
Orthopedic surgery should be consulted urgently, emergent consultation is not necessary, for patients that want to retain function as well as for partial tears that do not respond to nonoperative management. Mean strength measured in patients who were surgically managed was 25.7% higher in elbow flexion and 27.6% higher in forearm supination compared to those managed nonoperatively. [5]
References:
[1] Dold, A. (Ed.). (2024, March 3). Distal biceps avulsion. Orthobullets. https://www.orthobullets.com/shoulder-and-elbow/3081/distal-biceps-avulsion
[2] John Gray Seiler, Larry M. Parker, Patricia D.C. Chamberland, Gillian M. Sherbourne, Walt A. Carpenter. The distal biceps tendon: Two potential mechanisms involved in its rupture: Arterial supply and mechanical impingement. Journal of Shoulder and Elbow Surgery, Volume 4, Issue 3, 1995, Pages 149-156. ISSN 1058-2746. https://doi.org/10.1016/S1058-2746(05)80044-8.
[3] O'Driscoll S.W., Goncalves L.B., Dietz P. The hook test for distal biceps tendon avulsion. American Journal of Sports Med. 2007;35(11):1865–1869. doi: 10.1177/0363546507305016.
[4] Vishwanathan, K., & Soni, K. (2021, May 20). Distal biceps rupture: Evaluation and management. Journal of Clinical Orthopaedics and Trauma. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8167284/
[5] Austin M. Looney, Jonathan Day, Blake M. Bodendorfer, David Wang, Caroline M. Fryar, Jordan P. Murphy, Edward S. Chang. Operative vs. nonoperative treatment of distal biceps ruptures: a systematic review and meta-analysis. Journal of Shoulder and Elbow Surgery, Volume 31, Issue 4, 2022. Pages e169-e189. ISSN 1058-2746. https://doi.org/10.1016/j.jse.2021.12.001.
