Effectiveness of tendon transfers for massive rotator cuff tears: a simulation study

Objective. To determine what the most effective tendon transfer is in the case of a dysfunctional rotator cuff. Design. A tendon transfer procedure of latissimus dorsi, teres major or a combination of these two to the insertions of either teres minor, infraspinatus, supraspinatus, or subscapularis is simulated using a biomechanical musculoskeletal model of the upper extremity. Background. Massive rotator cuff tears are not easily repaired. To compensate for this loss of rotator cuff function other techniques like muscle transfers are developed. Methods. Three range of motion tasks and six activities of daily living of 24 subjects were measured. Kinematics from these tasks were used as input to the Delft Shoulder and Elbow Model. The muscle parameters of the Delft Shoulder and Elbow Model were modified to simulate a rotator cuff tear and the ability to perform the measured tasks with and without simulated transfer procedures was checked. Results. The highest improvements (28-30%, P = 0.00) in the ability to perform tasks were observed after a simulated tendon transfer of either both muscles or teres major alone attached to the supraspinatus or infraspinatus insertion. Although all transfer procedures produce significant improvements (P = 0.00), there is a significant difference between the procedures (Chi square = 58.8, P = 0.00) dependent on attachment site. Conclusions. According to the simulation procedure used in the current study, a tendon transfer of teres major and latissimus dorsi or teres major alone to the supraspinatus insertion appears to be the most effective procedure in the case of a dysfunctional rotator cuff. Practical factors, like subacromial space, volume of the muscles and tendons, tensile properties and the ability to split the muscles, will finally determine which is the preferred transfer option.