Long Head Biceps Tendon Function

Disorders of the tendon of the long head of the biceps brachii (LHB) are common. Many studies have attempted to identify the role of the LHB in shoulder function, but its significance in glenohumeral kinematics remains unclear. Some investigators describe the LHB as merely a vestigial structure, which may passively stabilize the shoulder, while others have emphasized its critical role as an active stabilizer of the glenohumeral articulation. Given the lack of consensus on the true function of the LHB in shoulder function, debate persists over surgical strategies to manage both isolated LHB pathology and disorders involving both the LHB and other critical shoulder structures, such as the rotator cuff.

Currently, the investigational techniques available to measure shoulder motion (kinematics) in vivo are quite limited, as there is no practical way to measure the motion of the scapula reliably or with accuracies required to fully appreciate the subtle rotations and translations of the glenohumeral joint. Therefore, new experiments are needed to improve our understanding of the shoulder. We are investigating the function of the LHB with the dual-plane fluoroscopy system that captures the osseous anatomy directly in vivo by measuring true 3D shoulder kinematics during dynamic activities with sub-millimeter accuracy.

Our aims for the study are to measure glenohumeral kinematics in the shoulders of subjects who have undergone unilateral biceps tenodesis (test shoulder) and compare it with the unoperated, normal shoulder (control group). This will show the side-to-side differences with and without the effects of the LHB. Subjects will serve as their own internal controls to minimize variability. Five subjects with a history of isolated LHB pathology treated by sub-pectoral biceps tenodesis and a normal, asymptomatic opposite shoulder have been recruited for this study. Four subjects have already been tested.

The general hypothesis of the study is that the LHB confers stability to the glenohumeral joint.