Is the biceps tendon necessary for normal shoulder function?
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The biceps tendon has a role
The long head of the biceps and its glenoid labral attachment, the biceps labral complex, constitute an integral part of the anatomy optimizing ball-and-socket kinematics and dynamic glenohumeral joint stability in shoulder function.
It accomplishes this by the following two roles:
- facilitating general glenohumeral joint stability through humeral head depression and by stabilization in abduction/external rotation motions, both of which potentiate concavity/compression; and
- producing a dynamic tension band, which controls the small anterior and inferior humeral head translations necessary to produce skid bed (translations and rotations) mechanics that maximize ball-and-socket kinematics and concavity/compression, while blocking deleterious humeral head posterior translations.
In these roles, the biceps/biceps labral complex has a clear effect on the glenohumeral joint stability ratio (translational shear force divided by glenohumeral joint-stabilizing compression force), helping to minimize shear force and maximize compression force.
Biceps labral complex roles are important in general shoulder function, which requires relatively lower loads, smaller ranges of motion and slower rotational velocities. However, these roles are indispensable for the function of the overhead throwing shoulder, whose higher loads, larger ranges of motion, faster rotational velocities and higher translation forces require greater precision of ball-and-socket kinematics. In two biomechanical studies, loss of biceps labral complex tension created posterior humeral head translation, and removal of the biceps labral complex attachment by tenodesis significantly altered the glenohumeral joint stability ratio, leading to the conclusion that tenodesis cannot be used as primary treatment in baseball players. In addition, alteration of the biceps labral complex by 11 o’clock anchor placement alters the tension band effect, creating nonphysiologic anterior and inferior humeral head translations, which adversely affect glenohumeral kinematics. Techniques that repair the biceps labral complex attachment to its normal 10 o’clock position restore glenohumeral joint kinematics.
Biceps labral complex functional roles can be affected by loss of glenohumeral external and internal rotation range of motion, decreased scapular retraction strength resulting in internal impingement and acquired biceps inflexibility and decreased eccentric strength, all of which can be created through repetitive overhead throwing motions and are productive of biceps labral complex tension and pain. These factors can be addressed by physical therapy without requiring tenodesis, and tension-based pain from the loss of the posterior biceps labral complex attachment in posterior labral tears can be addressed by posterior labral repair without requiring tenodesis.
Loss of biceps labral complex attachment by biceps tenodesis is an irreversible procedure with demonstrated adverse effects on glenohumeral joint kinematics. It should be performed with caution in overhead throwing athletes and only when careful examination demonstrates true pathology to the biceps labral complex.
- References:
- Dvir Z, et al. J Biomech. 1978;doi:10.1016/0021-9290(78)90047-7.
- Eichinger JK, et al. J Shoulder Elbow Surg. 2023;doi:10.1016/j.jse.2022.12.015.
- Kibler WB, et al. Arthroscopy. 2022;doi:10.1016/j.arthro.2022.02.001.
- Kibler WB, et al. J Shoulder Elbow Surg. 2024;doi:10.1016/j.jse.2023.06.031.
- Klemt C, et al. Clin Biomech. 2022;doi:10.1016/j.clinbiomech.2022.105819.
- Rauck RC, et al. J Shoulder Elbow Surg. 2022;doi:10.1016/j.jse.2021.12.026.
W. Ben Kibler, MD, is medical director emeritus at the Shoulder Center of Kentucky and medical director at the Institute of Clinical Outcomes and Research in Lexington, Kentucky.
Remove the biceps
The functional importance of the long head of the biceps tendon remains a source of debate. However, with the current biomechanical and clinical evidence, I do not believe the biceps tendon is necessary for normal shoulder function in most cases.
Biomechanical studies have demonstrated that the biceps tendon has no critical role in abduction of the arm, and its loss of function does not appear to increase loads required for the supraspinatus muscle/tendon complex to perform the same action of abduction. Other clinical studies using electromyography and fluoroscopy have also shown the long head of the biceps tendon does not exhibit significant activity during isolated shoulder movements and has minimal impact on glenohumeral movement. Of note, when we examined the clinical outcomes and satisfaction rates of patients undergoing long head biceps tenotomy or tenodesis with concomitant rotator cuff repair, we found no clinically significant difference.
In another randomized controlled trial of patients with isolated lesions of the long head of the biceps tendon, we found tenodesis and tenotomy did not differ for outcomes of pain or function at 2 years postoperatively. Investigations in patients with musculocutaneous nerve palsy further sheds light on the role of the long head of the biceps tendon. Several studies have highlighted that even in the presence of musculocutaneous nerve palsy, shoulder function can be preserved including use for high-level activities such as overhead throwing. Hence, despite complete denervation of the biceps brachii, brachialis and coracobrachialis muscles, patients are still able to achieve significant functional recovery of shoulder movements through other muscle groups and compensatory mechanisms.
Collectively, these findings indicate that the biceps tendon does not actively contribute to shoulder kinematics. When considering shoulder stabilization, studies have shown that, although the long head of the biceps tendon attaches to the superior labrum and contributes to glenohumeral stability, the integrity of the shoulder joint remains functional even with a deficient biceps tendon. Thus, while basic science suggests the long head of the biceps tendon may provide some degree of posterior stabilization and contribute to shoulder stability under certain conditions such as overhead motions, its absence does not significantly impair overall shoulder function, making it nonessential for normal shoulder mechanics. In addition, there have been no clinical studies to date demonstrating negative subjective or objective outcomes related to the absence of the long head biceps following tenodesis.
- References:
- Chalmers PN, et al. Knee Surg Sports Traumatol Arthrosc. 2016;doi:10.1007/s00167-015-3774-6.
- Giphart JE, et al. Am J Sports Med. 2012;doi:10.1177/0363546511423629.
- Leroux T, et al. Sports Health. 2015;doi:10.1177/1941738114539627.
- Levy AS, et al. J Shoulder Elbow Surg. 2001;doi:10.1067/mse.2001.113087.
- Mellano CR, et al. Instr Course Lect. 2015;PMID:25745939.
- Pages L, et al. Orthop Traumatol Surg Res. 2020;doi:10.1016/j.otsr.2020.03.033.
- Shavana G, et al. J Shoulder Elbow Surg. 2022;doi:10.1016/j.jse.2021.12.014.
- Strauss EJ, et al. J Shoulder Elbow Surg. 2014;doi:10.1016/j.jse.2013.07.036.
- Verma NN, et al. J Bone Joint Surg Am. 2021;doi:10.2106/JBJS.20.02086.
Nikhil N. Verma, MD, is professor and director of the division of sports medicine and director of the sports medicine fellowship at Rush University Medical Center in Chicago.
Melissa L. Carpenter, BS, is a clinical research fellow at Rush University Medical Center in Chicago.
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