In vivo evaluation of the kinematics of the long head of the biceps tendon within the pulley: A 3 T MRI motion analysis

To evaluate the kinetic amplitude and direction of the long head of the biceps tendon (LHB) within the pulley and the proximal bicipital groove, we performed a 3T-magnetic resonance-throwing motion analysis. This prospective study was performed on a 3T-MRI scanner. A T2-weighted-3D sequence in three specific positions of throwing motion of the dominant shoulder was performed under isometric 5 N loading conditions or without loading, respectively. Measurements were performed in high (140A degrees) abduction/external rotation, medium (110A degrees) abduction/external rotation and low (45A degrees) adduction-flexion/internal rotation. Multiplanar rotational reconstructions along the LHB in the bicipital groove allowed for the localization of the LHB including the degree of motion in the three most proximal slices. 12 healthy volunteers (age 22-34 years) were enrolled. Adduction led to an anterior deviation of the LHB within the bicipital groove. Loading conditions in medium (110A degrees) elevation/external rotation furthermore led to a significant anterior deviation of the LHB. Our findings support the thesis that pulley lesions result from movements of the LHB especially in extreme positions during throwing/overhead activities. Load application in the medium (110A degrees) elevation/external rotation position might enable a better evaluation of patients with dedicated pulley lesions. These results need further evaluation in larger study cohorts and in patients with dedicated rotator cuff lesions, which will be the focus of ongoing studies.