The Role of the Biceps Tendon
April 1, 2000 3 minutes read
The Role of the Biceps Tendon
Abstract & Commentary
Synopsis: The biceps tendon (BT) may add some glenohumeral joint stability, but the magnitude of force transmitted through active BT contraction is small and possibly insignificant.
Source: Goldfarb C, Yamaguchi K. The biceps tendon: Dogma and controversies. Sports Med and Arthroscopy Rev 1999;7: 93-102.
The role of the long head of the biceps tendon (BT) in shoulder motion and stability has been debated for many years. The BT was originally thought to be a primary source of shoulder pain. EMG data from the 1950s showed the BT to play an active role during shoulder forward flexion and abduction,1 therefore correlating biceps activity with shoulder mobility and stability. In 1972, Neer described the pathology of rotator cuff impingement and identified anterolateral acromial spurring as a primary source of shoulder pain. He showed that acromioplasty alone could relieve pain even in shoulders with significant BT degeneration. Neer warned against unnecessary biceps tenodesis because he felt that the biceps tendon imparted active humeral head depression.2
In this review of the literature, Goldfarb and Yamaguchi cite several basic scientific, anatomic, and biomechanical studies to elucidate the true role of the BT. An anatomical comparative study showed that the BT progresses anteromedially as quadripeds are compared to bipeds. This loss of abduction force has been compensated by developmental adaptation of the deltoid muscle.3,4 Hitchcock and Bechtol thus concluded that tenodesis of the BT does not "materially weaken the shoulder."3 Several EMG studies have documented biceps muscle activity during shoulder motion, but most of the activity was actually related to elbow flexion.4-6 Two recent studies showed no significant biceps muscle activity related to shoulder activity when elbow activity was eliminated by bracing the elbow.7 One in vivo study measured a small increase in superior humeral head translation during shoulder abduction in seven patients with loss of BT activity. Goldfarb and Yamaguchi thus conclude that the BT may add some glenohumeral joint stability, but the magnitude of force transmitted through active BT contraction is small and possibly insignificant.
Comment by Stephen B. Gunther, MD
Controversy about the role of the long head of the BT has existed for many years. It is widely accepted that the BT plays a role in the rotator cuff impingement syndrome. An inflamed or partially torn BT can cause anterior shoulder pain. However, the role of the BT in glenohumeral joint stability is not universally agreed upon. Therefore, opinions differ about the use of tenodesis of the BT as a solution for painful, degenerative afflictions of the tendon.
Does tenodesis of a diseased biceps tendon alter function of the shoulder? It would appear from this review that the biceps provides a minimal contribution to shoulder stability, although the contribution may be more significant in cases of rotator cuff dysfunction. In light of the fact that patients who spontaneously rupture the BT long head often do well, some surgeons now recommend tenotomy rather than tenodesis for a damaged tendon. This is an area that needs further study.
This article is a must read for any practitioner who is intrigued by the long head of the biceps tendon. There is a thorough discussion about the role of the BT in the human shoulder as well as the pathophysiology and treatment options.
References
1. Basmajian JV, Latif A. Integrated actions and functions of the chief flexors of the elbow. J Bone Joint Surg Am 1957;39:1106-1118.
2. Neer CS 2d. Impingement lesions. Clin Orthop 1983; 173:70-77.
3. Hitchcock HH, Bechtol CO. Painful shoulder. Observations on the role of the tendon of the long head of the biceps brachii in its causation. J Bone Joint Surg Am 1948;30:263-273.
4. Inman VT, et al. Observations of the function of the shoulder. J Bone Joint Surg Am 1944;26:1-30.
5. Neer CS 2d. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: A preliminary report. J Bone Joint Surg Am 1972;54:41-50.
6. Jobe FW, et al. An EMG analysis of the shoulder in pitching. A second report. Am J Sports Med 1984;12: 218-220.
7. Yamaguchi K, et al. Biceps activity during shoulder motion: An electromyographic analysis. Clin Orthop 1997;336:122-129.
Which statement is incorrect regarding the long head of the biceps tendon?
a. It is often degenerated in patients with rotator cuff tears.
b. It is the primary active stabilizer of the glenohumeral joint.
c. It performs a different function in human beings than in quadripeds.
d. It may cause anterior shoulder pain when inflamed or partially torn.
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