Causes / typical injury mechanism: The biceps brachii muscle originates from 2 heads, the long head and the short head, that merge distally. While the biceps tendon may rupture distally or proximally, 96% of biceps tendon ruptures occur proximally and involve the long head. Proximal biceps tendon rupture (PBTR) is typically due to degeneration; however, it can occur more acutely due to injury.

Medial subluxation or dislocation of the long head biceps tendon can occur with repetitive mechanical wear, overuse, or acute trauma. The long head biceps tendon is located inferiorly in the bicipital groove, but ligament deterioration may free the tendon from the bicipital groove. Rotator cuff tears are commonly associated.

Classic history and presentation: PBTR is most commonly due to chronic shoulder degeneration from recurring microtrauma to the tendon, resulting in eventual rupture. However, rupture can occur more acutely after a fall, or in athletes and weight lifters. Patients typically present with pain in the anterior shoulder, swelling and bruising in the arm and/or elbow, minor loss of supination, and a deformity to the contour of the anterior arm.

Prevalence:

• Age – The most common group affected is between the ages of 40 and 60 years; however, this condition can occur in younger individuals, especially young athletes.
• Sex / gender – Male predominance.

Risk factors: Risk factors include chronic biceps tendonitis, rotator cuff injury, advanced age, and male sex. While recent fluoroquinolone and steroid use has been shown to be a risk factor in distal biceps tendon rupture, there is little evidence concerning these drugs and PBTR. However, it is likely that they do increase risk.