Mysterious Arm Mass
On a recent shift, one of my colleagues fielded a call from a local urgent care reporting that they were sending in an 88 year old, otherwise healthy man with a “left arm mass.”
The patient reported doing yard work the prior day, pulling down and trimming tree branches. Shortly thereafter, he noticed a soreness in his left shoulder and a swelling in his arm just proximal to the antecubital fossa.
This is what I found on exam:
The patient had a proximal biceps tendon rupture.
Biceps tendon ruptures can be either proximal or distal, the former being far more common.
In proximal injuries, the patient may describe a “pop” and subsequent soreness in the anterior shoulder. Flexion of the arm should cause pain and produce a mid-arm ball that is prominent when compared to the contralateral arm. There is usually minimal loss of strength due to the contributions of the brachialis and supinator muscles.
In distal injuries, the mechanism usually involves a flexed arm with a load placed such as to forcefully extend the arm. Pain is felt in the antecubital fossa. The biceps squeeze test can be employed to diagnose this injury. With the arm flexed at 60-80 degrees, squeeze the biceps. In the normal arm, this should a elicit supination of the forearm. The absence of supination indicates a positive test. The hook test can also be performed to diagnose this injury. With the arm flexed to 90 degrees, the examiner should be able to hook the index finger under the distal biceps tendon. A positive test is indicated by inability to hook the finger under the tendon. Loss of strength is more significant in distal ruptures when compared to proximal ruptures.
ED management of both injuries consists of ice, analgesics, application of a sling, and orthopedic follow up.
In proximal and distal injuries you may consider plain films of the shoulder and the elbow respectively, as avulsion fractures may occur at the insertion point of the tendon.
Biceps tendon injuries are often surgically repaired in young, active patients, but may be deferred in elderly patients in whom activities of daily living are not affected.
Chow, Yvonne C. "Elbow and Forearm Injuries." Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York, NY: McGraw-Hill Education LLC., 2011. 1816-828. Print.