Summary

, LTTT is a suitable salvage procedure for any degree of fatty infiltration of teres minor, and should be strongly considered as an alternate procedure to latissimus dorsi tendon transfer in patients with high grade teres minor fatty infiltration.

Abstract

Introduction

Surgical management of massive irreparable rotator cuff tears has increasingly used salvage procedures such as tendon transfers to preserve the glenohumeral articulation in young patients. Appropriate patient selection for tendon transfers is crucial to surgical success, yet there is a paucity of evidence investigating factors that lead to improved post-operative outcomes. Success of latissimus dorsi tendon transfer has been linked to a low level of fatty infiltration of the teres minor muscle belly. However, the effect of teres minor fatty infiltration has not been studied in newer surgical techniques such as the lower trapezius tendon transfer (LTTT). This study aims to correlate post-operative outcomes of LTTT in massive irreparable rotator cuff tears to the degree of fatty infiltration of teres minor.
Materials & Methods: This is a prospective longitudinal observational study. All patients with massive rotator cuff tears undergoing arthroscopic assisted LTTT (as previously described) by a single fellowship trained upper extremity surgeon were screened. The research coordinator undertook the consenting process if the patient agreed to be approached for the study. For all consented patients, fatty infiltration of teres minor was graded using the Goutallier classification based on pre-operative MRI by two orthopaedic surgeons not involved in performing the surgery. Two groups were created based on teres minor fatty infiltration: Group A included Grades 0 and 1 (no or little fatty infiltration) and Group B included Grades 2 to 4 (moderate to severe fatty infiltration). Participants completed a demographic form, and the SANE score and a satisfaction questionnaire were completed at pre-, 12- and/or 24-months post-operative. At all study time points, range of motion and isometric strength of forward elevation, abduction, and external rotation (ER) in neutral and 90° abduction) using a hand-held dynamometer were measured by a research athletic therapist blind to Goutallier grade. Lag sign test was performed. Between group comparisons were performed using independent t-tests assuming unequal variance and pre- vs post-operative comparisons were performed for each group using paired t-tests. Rate of external rotation (ER) lag sign was compared between groups using Fisher’s exact test. Significance was defined as p < 0.05.

Results

Twenty-six patients met the study inclusion criteria, with 18 patients included in Group A and 8 in Group B. There were no differences between groups with respect to pre-operative SANE score, degrees of active forward elevation, and degrees of active ER. Eight of 18 patients (44.4 %) in Group A had an ER lag sign, compared to 5 of 8 patients (62.5%) in Group B, but this was not statistically significant (p = 0.672). Significant post-operative improvements in SANE score were found in both groups with no differences between groups. Pre-operative ER strength of the affected arm with the arm adducted was significantly different in Group A (3.9kg) versus (Group B (0.58kg; p = 0.011; Figure 1). However, ER strength was similar post-operatively (p = 0.587).

Discussion

Lower trapezius tendon transfer provides in-phase motor activity and anatomic line of pull to the infraspinatus and teres minor muscles. In our study, patients with any degree of fatty infiltration of teres minor benefited from LTTT and experienced improvement in patient reported outcomes. Patients with moderate to severe teres minor fatty infiltration (Group B) had lower baseline ER strength, but this difference was no longer evident post-operatively. Although overall patient numbers in this study are small given the rarity of this condition and procedure, these outcomes suggest that LTTT provides significant benefit to patients, independent of the degree of fatty infiltration to teres minor. This is in contrast to the latissimus dorsi tendon transfer, which is less successful in patients with moderate to severe teres minor fatty infiltration. Taken together, LTTT is a suitable salvage procedure for any degree of fatty infiltration of teres minor, and should be strongly considered as an alternate procedure to latissimus dorsi tendon transfer in patients with high grade teres minor fatty infiltration