Effects of latissimus dorsi tendon transfer on shoulder motion and muscle activation: A follow-up observational study

BACKGROUND: Improvements in maximal flexion-extension, adduction-abduction, and in the activity as an internal rotator of the latissimus dorsi (LD) muscle during circumduction movements were found six months after arthroscopically assisted latissimus dorsi transfer (LDT) for massive irreparable cuff tears. The aim of this study was to observe whether these improvements and the LD activity were maintained after a longer follow-up period. METHODS: The shoulder kinematics of 6 out of the 9 participants of the previous study were assessed through a 3-D motion analysis system after 42.5±1.8 months (T3) and compared with the previous assessments at 6 months (T2) post LDT and with preoperative data (T0). The activity of the LD muscle was measured through surface electromyography in three different postures. RESULTS: No significant differences between T2 and T3 were found for the parameters that improved at T2. A significant improvement in horizontal abduction-adduction was found between T2 and T3 (P=0.028) and T0 and T3 (P=0.028). A significant difference in horizontal abduction-adduction relative difference with the non-operated side between T0 and T3 (P=0.043) was found. No significant differences between T2 and T3 in the other parameters were found. CONCLUSIONS: The effects of LDT on shoulder biomechanics were maintained, and horizontal abduction-adduction movement improved, after a long time from LDT. The LD muscle did not change or increase its function as an external rotator.