The biceps muscle is the large muscle over the front of the arm that extends from the elbow to the shoulder joint. The biceps muscle is especially important both with bending the elbow, and also turning the forearm to have the palm facing upwards. This movement, called supination, may not seem particularly important, but when going to open a door knob or when turning a screwdriver, the importance becomes quite apparent!
The Biceps Tendon
The biceps muscle is attached at both the top and the bottom to the bone through structures called tendons. The muscle itself is thick, contractile tissue that allows the body to pull with force. The tendons, on the other hand, are very strong, but small and noncontractile structures that connect the muscle to the bone.
There are tendons at the top of the biceps muscle and at the bottom of the biceps muscle. The tendons at the top of the biceps muscle are called the proximal biceps tendons, and there are two of these. The tendons at the bottom of the muscle are called the distal biceps tendon, and there is only one of these.
The distal biceps tendon is located at the crease of the elbow and can be felt, and often seen, when pulling the forearm against a heavy object. Tears can occur at either the proximal or the distal biceps tendon, and the treatments may differ significantly depending on which injury occurred.
Distal Biceps Tendon Tears
Injuries to the distal biceps tendon are not uncommon. Most often occurring in middle-aged men, these injuries often occur when lifting heavy objects. Over 90 percent of distal biceps tendon tears occur in men.1
They are much more common in the dominant arm with over 80 percent of injuries occurring on the dominant side. While the perception is that these injuries are often associated with athletic activities or very high demand work activities, the reality is that most often they occur unexpectedly during a seemingly normal lifting activity.
The mechanism by which a tear occurs is called an eccentric contraction. 2 This means that the biceps muscle was contracting, such as trying to lift a heavy object, but the force acting on the muscle was pulling in the opposite direction.
As stated, biceps tears of the distal biceps tendon occur almost exclusively in men. While there are case reports in the medical literature of these injuries in women, the vast majority occur in men. In addition, people who smoke tobacco products have a much higher chance of sustaining a distal biceps tendon tear. In fact, the likelihood of sustaining a tear is more than 7 times that of nonsmokers.
Signs of a Torn Biceps
The most common description that is given by people who tear their biceps tendon at the elbow is that they hear a loud “pop” as they are lifting a heavy object.3 The typical symptoms of a torn biceps include:4
- Pain around the crease of the elbow
- Swelling of the elbow region
- Bruising over the elbow and forearm
- Deformity of the biceps muscle
A skilled examiner is able to feel the biceps tendon and should be able to determine if there is a rupture of the tendon on examination. There is actually a test called the “hook test” where the examiner attempts to hook her index finger over the biceps tendon as the muscle is contracted. If the tendon is ruptured, she will be unable to hook the finger over the tendon. This test has been determined to be extremely accurate for detecting a torn biceps tendon.5
While imaging studies may not be necessary for every situation, they are often used to exclude other potential causes of elbow pain and to confirm the suspected diagnosis. An x-ray is a helpful test to ensure there is no evidence of fracture around the elbow joint, and that the bones are lined up normally. 6 A biceps tendon tear will not show up on an x-ray test, but it can be used to exclude other potential causes of discomfort.
An MRI is a test typically used to identify a torn biceps tendon. If there is a question about the diagnosis, an MRI can be helpful. In addition, MRIs can be helpful to identify other soft tissue injuries.7 Some orthopedic providers are becoming increasingly skilled with the use of ultrasound in order to quickly confirm this type of diagnosis. Your orthopedic surgeon may elect to obtain an ultrasound to confirm their suspected diagnosis.
Most often, injuries to the distal biceps tendon are complete tears. Typically, the tendon tears directly off of the bone in the forearm.8 Lacerations further up the tendon are uncommon but can occur if there is a direct injury to the tendon such as with a knife blade. Partial injuries to the biceps tendon attachment can also occur.
In these situations, the tendon will feel intact, but pain may not resolve with simple treatments. In people with partial tears, if simple treatment steps do not alleviate symptoms of discomfort, surgery can be considered to fully detach the tendon and then repair it back to the bone solidly.4
Nonsurgical Treatment Options
Nonsurgical treatment is an option for the management of a distal biceps tendon rupture.9 While many people, including surgeons, have the notion that all biceps tendon ruptures require surgical treatment, the reality is that some people do very well with nonsurgical treatment.
This is particularly true in patients who have lower demands, such as elderly individuals. In addition, when the injury occurs on the non-dominant arm, people tolerate a chronically torn biceps tendon much better.8 There has been extensive research into the deficits experienced by people with a chronically torn biceps tendon. There are generally three functional deficits that occur:4
- Decreased flexion strength: The strength of the elbow to flex will diminish by about a third with a chronically torn biceps tendon.
- Decreased supination strength: The strength of the forearm to turn into a palm-up position, such as opening a doorknob or turning a screwdriver, will decrease by about half.
- Decreased endurance: The endurance of the extremity tends to diminish overall making repetitive activities a little more difficult.
In addition to these changes, people with a chronically torn distal biceps tendon typically notice an abnormal shape of the biceps muscle.8 In some people, this can lead to cramping sensations or muscle spasm, although these symptoms typically diminish over time.
For most people who sustain a distal biceps tendon injury, surgery will be discussed as a treatment option. There are a number of surgical treatments and techniques that can be used to repair the distal biceps tendon. The usual variation in surgical technique is either to perform the surgical repair through a single incision, or a two-incision technique.10 Different surgeons have different preferences regarding how to best repair the damage to the biceps tendon.
In addition, some surgeons are exploring opportunities to perform the surgical procedure through an endoscopic approach, although this is much less common. There are many studies to determine which of these techniques is best, and each technique will have its own advantages and disadvantages, and no clear technique is “the best.”
There are also a number of different ways to attach the damaged tendon back to the bone. The tendon nearly always tears directly off of the bone. Different types of anchors and devices can be used to attach the torn tendon back to the bone, or it can be repaired into small drill holes into the bone.11 Each surgeon has a preferred technique in order to repair the damaged tendon. My best advice is to discuss these options with your surgeon, but have them perform their most comfortable technique.
Rehabilitation and Complications
The rehabilitation protocols following surgical treatment vary significantly between individual surgeons. In general, most surgeons will recommend immobilization in a splint after surgery for a few weeks to let swelling and inflammation settle down. Gentle range of motion will begin, but strengthening should be avoided for the first 6-8 weeks. Return to full strength activities is typically not allowed until a minimum of 3 months and sometimes longer.12
Complications of surgical treatment are uncommon but can occur. The most common complication is irritation or damage to the sensory nerves of the forearm. This nerve, called the lateral antebrachial cutaneous nerve, provides sensation to the front of the forearm. When this nerve is injured at the time of surgery, people can experience numbness or tingling over the front of the forearm.13 More significant nerve injuries are possible but very uncommon.
The other complication unique to distal biceps tendon surgery is the development of something called heterotopic bone formation. This means that bone can develop in the soft tissues between the forearm bones. This unusual complication can limit the mobility of the forearm. Infection is always a potential complication with surgical treatment. Typically infections can be prevented with steps taken at the time of surgery, and appropriate care of the surgical incision during the postoperative period.14
Surgery is best performed sometime within a few weeks following the initial injury that caused the biceps tendon to tear.15 Chronic biceps tendon injuries that are either undiagnosed or untreated for months can be more difficult to repair surgically. In some situations, these chronic tears may require the use of a tendon graft in order to restore the normal length of the biceps tendon.16
When the initial injury occurs, the biceps tendon is pulled back away from its normal attachment. Over time, the tendon and muscle will lose its elasticity and scar down, making it more difficult to bring out to normal length. If the length is insufficient to allow for attachment, a tendon graft may be necessary in order to bridge the gap.16 This can lengthen the time needed for rehabilitation and limit the restoration of expected function.
A Word From Verywell
Distal biceps tendon injuries are a potential source of significant pain and weakness of the upper extremity. While the diagnosis of these injuries is usually clear, the treatment decision can be difficult for some people. Surgery tends to be a safe and effective way to ensure functional recovery, but there are possible risks of surgery.
Deciding the best treatment depends on a number of factors including how long it has been since your injury, dominant versus non-dominant extremity, and expectations for use of the extremity. Talking with your doctor can help ensure you make the best decision for your particular situation.