Distal biceps rupture
Approximately 1.2 out of 100,000 people annually will sustain a Distal Biceps Rupture. This means that the lower attachment of the biceps muscle tendon at the elbow has torn away from the bone. Most often these are traumatic injuries that occur when the arm is resisting a heavy downward motion and the tendon tears away from the forearm bone. This is commonly seen in weight lifters while doing biceps curls or workers lifting or trying to catch a falling heavy box or object. Other sporting activities have been reported such as doing “muscle-ups” in Crossfit.
The biceps muscle attaches at two points in the shoulder and attaches at one point in the elbow to the radius bone in the upper forearm. This lower or “distal” attachment provides added strength for bending or flexion of the elbow and also provides strength for supination of the forearm which is turning the palm upward. The brachialis muscle also bends the elbow and the supinator also provides rotational strength to the forearm.
The vast majority of these injuries occur in males with average age around 50 years old, and many are weight lifters. Other risk factors include smoking and anabolic steroid use both of which may weaken the Distal Biceps tendon allowing for rupture when it is over-stressed.
When catching a heavy object or when bringing down weights during a biceps curl the muscle is contracting, but also lengthening at the same time. This generates the highest possible forces in the muscle and tendon and is a typical moment at which the Distal Biceps Rupture occurs. Typically the tendon will tear away from the bone (radius) of the forearm, and less commonly it will tear in mid-tendon or at the junction where muscle turns into tendon.
Most people will notice a sharp pain and pop when the tear occurs and notice a loss of normal contour to the biceps in the upper arm. It will appear to be retracting upwards. There will also be swelling and bruising and pain with movement. After the initial injury people are still able to bend and move the elbow. Orthopaedic surgeons use what is called a “hook test” which is hooking your finger around the intact biceps tendon on the uninjured arm. Then the same is attempted on the injured arm. If the tendon cannot be felt or “hooked” then it is likely torn. MRI will be done to confirm is the tear is from the bone or other location.
Seeking an orthopaedic surgeon evaluation immediately after a suspected Distal Biceps Rupture is very important. The vast majority of these are recommended for surgical repair and the best repair can be achieved if done within the first 1-2 weeks of injury. Surgical treatment 3-4 weeks and beyond after injury can create significant technical challenges and worse outcomes as the tendon continues to retract. The may lead to an inability by the surgeon to get the tendon all the way back to the radius bone for repair. This may then require more complex reconstructive types of procedures to achieve an intact distal biceps.
In some older and less active patients it may be acceptable to leave the biceps tendon torn, and over time they will regain most of their elbow flexion (bending) strength, but will typically lose about 30-40% of their supination (palm upward) strength. For most active patients we recommend surgical repair to obtain the best possible future outcome.
The surgical procedure for Distal Biceps Rupture is outpatient and typically 1-2 hours. Through either 1 or 2 incisions, depending on surgeon preference, the tendon is re-inserted into the radius bone at its normal location. It is held in place either with suture anchors, metal button, or a screw. The arm is typically immobilized for 7-10 days after surgery and then range of motion with a physical therapist will begin. No resistance of any kind will be allowed for 6-8 weeks after the surgery to allow for tendon to bone healing. At this time a resistance program will being with most patient returning to normal activity in 4-5 months after surgery.
It is very important to be aware of the risk factors for Distal Biceps Rupture especially if you are in the 35-60 age group, and engaging in any heavy lifting or weight lifting activities. Proper warm-up and stretching is important. If you suspect you may have a Distal Biceps Rupture immediate evaluation by an orthopaedic surgeon can help to ensure you have to best available treatment options for this injury.