Masterclass: Distal Bicep Tendon Rupture - Part I

Athletes in contact and strength-based sports place an enormous amount of stress onto the distal bicep tendon. However, injuries to the distal biceps tendon are not common in athletes, accounting for 10% of all bicep tendon ruptures, with the long head of the proximal insertion rupturing most frequently. If an injury to the distal bicep tendon does occur, it usually in the dominant arm of middle-aged men (40-60yrs), suggesting a degree of degeneration must be present to rupture.

There have been a growing number of case reports in the media about these injuries – in particular athletes such as powerlifters and bodybuilders with a history of anabolic steroid use. More recent studies have shown that the incidence of this injury is increasing and the age group that sufferers is getting younger. It is believed that full tendon ruptures will require surgery to restore the biceps role as an elbow flexor and supinator of the forearm to prevent loss of strength in these movements.

Anatomy and biomechanics

The long head of the bicep originates from the supraglenoid tubercle of the scapula, and the short head arises from the coracoid process. It is common for the muscle to course distally as two separate heads or bellies, with the fibres from the short head on the ulnar side of the arm and the long head on the radial side. However, the two bellies may interdigitate closer to the elbow.

As the tendons course to the radial insertion, they twist counter clockwise in right arms, with the anteromedial fibres from the short head inserting inferiorly on the radial tuberosity, with the posterolateral long head inserting more superior on the tuberosity (see figures 1 and 2). It is suggested that this twisting arrangement differentiates the short head as primarily being an elbow flexor and the long head as a supinator.