Introduction
The bicep is a muscle of the upper arm and consists of two muscle parts – the short and the long head. These originate from two different parts of the shoulder and unite to form a common muscle belly where the muscle is visible from the outside. This is attached to the spoke, the thumb-side bone of the forearm, by a tendon.
Tendons are the ends of muscles consisting of connective tissue that attach them to the bone. Due to its two-part structure, the biceps has three tendons. In principle, a tear can affect all three tendons of the muscle.
However, by far the most frequently affected area is the tendon near the shoulder of the long biceps head (= “long biceps tendon“) on the dominant arm (up to 96% of all biceps tendon tears). With approx. 1%, tears of the tendon of the short muscle head (= “short biceps tendon“) are the rarest injuries. The tendon that connects the muscle belly with the forearm (= “distal/external tendon”) also tears relatively rarely, at approx. 3%.
Symptoms
A biceps tendon rupture results in restrictions of the muscle’s function to varying degrees, depending on the tendon affected. It is mainly responsible for the flexion and outward extension of the forearm, but also supports the lifting of the arm to the side and forward as well as the inward rotation of the whole arm. It should be noted that other muscles of the upper and forearm can at least partially take over these movements in the event of failure and compensate for the functional impairment caused by the tear.
During the tear itself, affected persons feel a sudden, stabbing pain. This can last, but is usually not very strong. Swelling and bruising can also occur.
If one of the tendons near the shoulder is affected, one often sees a shift of the muscle belly in the direction of the elbow as well as a dent in the arm above the muscle. The limitation of muscle strength when lifting and turning the forearm is often only slight because the other biceps tendon can compensate for the corresponding movements. This often leads to the fact that the symptoms are only slightly pronounced at the beginning and affected persons consult their doctor late.
If the distal tendon tears, the only connection between the muscle and the forearm is lost. This means that no more force can be transferred to the forearm and severe functional limitations of up to 60% occur when lifting and turning the forearm outwards. In addition, a shifting of the muscle belly towards the shoulder and a bulge formation under tension can then be observed.
If the biceps tendon tears near the base of the shoulder joint (proximal part), this tear is generally accompanied by little pain. However, unspecific shoulder pain may occur. In addition, there is often pressure pain in the sulcus intertubercularis.
The sulcus intertubercularis is a groove on the upper arm in which the long biceps tendon runs. If the biceps tendon tears in the area of the insertion at the elbow (distal part), acute stabbing pain usually occurs, accompanied by weakness in the flexion of the elbow. The rupture of the tendon can lead to bruising (haematoma).
This is usually evident after the rupture of the tendon after a very short time and can also be felt as a hard swelling in the area of the rupture. The bruise is also often painful when touched or pressed. Hematoma occurs more often when the distal tendon, which is located further to the elbow, tears.