Long head of biceps: the biomechanics of injury
Taken from “Conservative Management of Sports Injuries” (Hyde & Gengenbach 2007)
Chapter 13: The Shoulder, by Dr. Andreo Spina & Dr. Jason Pajaczkowski
Impingement and the Long Head of the Biceps Tendon (pg 525-526)
Tears of the supraspinatus will usually accompany tears of other tendons and occur befor ruptures of the biceps in a ratio of approximately 7 to 1. The biceps may rupture first if subjected to excessive impingement wear owing to shallowness or laterality of the bicipital groove.1 The synovial lining of the long head of the biceps is an extension of the synovium of the shoulder joint and the rotator cuff. Therefore, any inflammation of the cuff muscles or in the joint itself will inherently extend down along the biceps sheath. A narrow bicipital groove and restrictive transverse humeral ligament will further provoke the tenosynovitis, usually beneath or just distal to the transverse ligament, and the situation will become chronic.2
Most biceps tenosynovitis and ruptures are thought to be caused by subacromial impingement. Also, because of the biceps function to depress the humeral head, injury such as rupture or dislocation of the long head may escalate impingement because its restraining action is lost. Rupture of the biceps tendon is rare, even in the young adult sustaining severe trauma.3 Such injury occurs in young weight lifters, in whom acute rupture is provoked by a single violent effort. Usually, however, the tendon will become worn by repetitive stress, and the tear will occur in the weakened area. Steroid injections into such a weakened area can expedite the development of a complete tear of the biceps tendon.1 Very rarely is the biceps tendon the primary lesion of the shoulder. More commonly, rotator cuff insufficiency or glenohumeral instability will cause superior translation of the humeral head (either statically or dynamically), which results in impingement of the biceps tendon.
The biceps tendon may become worn due to a narrow tunnel-shaped intertubular groove, or it may dislocate medially. Acute fixed medial displacement or subluxation is rare but can occur due to a tear in the coracohumeral ligament. In cases of trauma, it is important to rule out osteochondral fracture involving the bicipital groove, or damage to the lesser tuberosity or subscapular tendon. A bicipital groove radiograph is necessary in diagnosis of any bony irregularities. The dimensions of the intertubercular groove can be measured radiographically and may help to assess the state of the bicipital tendon. An arthogram may also be necessary to detect the position of the tendon.
1. Ellman H. Shoulder arthroscopy: current indications and techniques. Orthop. 1988;11:45-51.
2. Neviaser TJ. The role of the biceps tendon in the impingement syndrome. Orthop Clin North Am. 1987;18:383-386.
3. Parsons I, Aprelvea M, Fu F, Woo S. The effect of rotator cuff tears on reaction forecs at the glenohumeral joint. J Ortho Res. 2002;20:439-446.