Muscle Activity of the Latissimus Dorsi after Tendon Transfer in Patients with Rotator Cuff Tears

Abstract

Background: Massive irreparable posterosuperior rotator cuff tears may result in the loss of external rotation. Most of the patients with posterosuperior rotator cuff tears suffer from a restriction in their daily life actions. Latissimus dorsi tendon transfer (LDTT) is a method to restore abduction and external rotation in these patients. However, the behavior of the LD after the transfer is not clear yet. Few studies have analyzed the activity of the LD after transfer. The goal of this study was to examine the function of the LD postoperatively in follow-up examinations during activities of daily life (ADLs) and during different movements evaluated by measuring the range of motion (ROM). Methods: We examined 12 patients 4.3 years (1–9 years) after LDTT, using simultaneous 3D motion analysis and surface Electromyography (sEMG) of 12 muscle parts; the opposite, nonaffected side was assessed as a control. The measurement protocol included two standardized movements (exorotation with an adducted arm and exorotation with 90° abduction) as well as two ADLs (combing hair and perineal care). Results: An average of 4.3 years (1–9 years) after LDTT, 9 of the 12 subjects showed EMG activity in the transferred LD during glenohumeral external rotation. During the endorotation phase, either little activity was registered or only the pectoralis major was active. During the ADLs, 6 out of 12 subjects showed EMG activity in the transferred LD while “combing hair”, whereas all subjects showed EMG activity during perineal care. Conclusion: The LD showed partial activity in its new role as an exorotator, but no clear difference was observed between some of the movements as well as in comparison with the healthy shoulder. Further studies will need to be conducted to better differentiate voluntary contractions and co-contractions as well as tension and extension in the muscle.

Shoulder muscle activity after latissimus dorsi transfer in an active elevation

“…Literature has not reached consensus with regard to the activity of the LD after transfer. 2 , 8 , 16 , 19 , 23 , 29 , 30 , 32 , 33 , 35 , 47 One of the reasons of this inconsistency might be the method of assessment and analyzing muscle activity results. Several authors measured the MIVC of the LD to compare preoperative and postoperative muscle activity, and found an increased postoperative LD muscle activity.…”

“…They attributed this finding to an active LD contraction after transfer in its new function. 23 , 30 , 31 However, MIVC is different to isokinetic movement of the shoulder and the LD muscle increased activity could be the result of increased co-contraction after transfer seen in patients with a cuff tear. 46 , 49 Others, used the contralateral LD muscle as a reference, set it to 100 % EMG max and reported EMG max values of LD in the surgical shoulder.…”

“…Similar to our study, 22 recent studies with analyzing isokinetic movements report no difference in LD muscle activation after LDT compared to the ACS. 15 , 30 …”

“…It has been postulated that the latissimus dorsi (LD) muscle changes its active function to its new mechanical role after the transfer, to elevate and externally rotate the arm. 8 , 15 , 16 , 23 , 29 , 32 , 34 Others did not find any change of LD muscle activity in active range of motion in the shoulder, and therefore attribute the function to the tenodesis effect, 30 , 33 referring to the downward directed pull of the LD on the proximal humerus, opposing the upward directed force of the deltoid in active elevation of the shoulder. This tenodesis effect might be able to create a more balanced force, acting on the GH joint, making elevation in the shoulder possible.…”

“… 15 , 28 Scapulothoracic muscles and recruitment timings have been analyzed in (massive) rotator cuff tears, 27 , 50 , 55 , 56 subacromial impingement, 9 , 10 , 48 , 51 , 55 glenohumeral instability, 51 shoulder muscle fatigue, 41 , 52 suprascapular nerve block, 40 and after LDT. 29 , 30 The studies reporting on muscle activity after LDT have solely focused on LD activity in its new mechanical role, whether it has changed its function from an internal rotator and adductor to an external rotator and abductor of the arm. It is not known which other shoulder muscles or changes in shoulder muscle recruitment time are responsible for the increased ST contribution in maximum active elevation of the shoulder (MAES) after LDT.…”