This is uncommon, only 3-5 people per 100,000 each year, however has been seen more often in the clinic recently. It is usually caused by a sudden injury when the elbow is forced straight against resistance, i.e. walking your dog while he/she is pulling and then he/she all of a sudden darts after a squirrel. The bicep muscle can be partially torn or completely torn from it’s attachment state at the radial tuberosity, located near the elbow. You may hear/feel a pop at the elbow during the time of injury and severe pain can subside in 1-2 weeks. Risk factors include men, >30 years, smoking, and use of corticosteroid medications. Once torn, the muscle/tendon will not grow back to the bone and heal without surgical intervention. In the meantime other arm muscles make it possible to bend the elbow without the use of the biceps tendon, but the motion of rotating the forearm from palm down to palm up is limited (supination).
Diagnosis is made when signs/symptoms include: visible bruising in the elbow and forearm, weakness in bending of the elbow, weakness in twisting the forearm (supination), a bulge in the upper part of the arm created by the recoiled, shortened biceps muscle and a gap in the front of the elbow created by the absence of the tendon. Imaging with ultrasound can show the free end of the biceps, however MRI is better as it can show both partial and complete tears.
Treatment depends on whether you want to resolve the full strength and range of motion of the affected arm. For those who don’t necessarily need full strength, which means a 30% to 40% reduction in strength, nonsurgical treatment such as rest, use of NSAIDs, and physical therapy is all that is needed. If surgery is considered, it should be done during the first 2-3 weeks of the injury. As you wait longer, the tendon tends to scar and shorten, making reattachment more difficult. After surgery, immobilization in a cast or splint and rehabilitation is required. It takes 3 months of recovery with the majority of the time returning to full strength and range of motion.