New insights in diagnosis and treatment of distal biceps pathology

Biceps brachii is composed of two separate heads and is innervated by a branch of the musculocutaneous nerve [1]. The proximal tendon of the long head is attached to the supraglenoid tubercle, and the proximal tendon of the short head is attached to the coracoid process. The biceps (muscle and tendon) rotates 90° externally from origin to insertion onto the bicipital tuberosity [2] and acts on three joints: the glenohumeral, ulnohumeral, and proximal radioulnar joints. A completely bifurcated distal tendon insertion is not uncommon [3, 4]. The short head of the distal biceps tendon was reported to insert more distally, and the long head was inserted more eccentric and medial. The moment arm of the long head was higher in supination, and the short head had a higher moment arm in neutral position and pronation [5]. These findings may allow functional independence and isolated rupture of each portion and may have consequences for restoring the native anatomy during a surgical repair. Several authors reported an isolated rupture of one of the two tendons in cases of bifurcated distal biceps tendons [4].