Summary

The preoperative T2 values of the SSP and ISP muscles in re-tear shoulders were significantly higher than those in intact shoulders, and T2 values of > 80 milliseconds in the SSP or > 60 milliseconds in the ISP suggest a high risk of re-tear.

Abstract

Introduction

It remains controversial whether fatty degeneration of rotator cuff muscles would affect the outcomes of rotator cuff repair. Many studies have evaluated fatty degeneration of the rotator cuff muscles with semi-quantitative methods, such as Goutallier staging; however, they may be poor in variability and insufficient to evaluate small differences. T2 mapping technique of MRI is reported to have potential to quantify fatty degeneration of the rotator cuff muscles and can provide better evaluation of fatty degeneration. The purpose of this study was to assess relationship between re-tear after arthroscopic rotator cuff repairs (ARCR) and preoperative fatty degeneration of the cuff muscles quantified using T2 mapping.

Methods

Fifty-six shoulders (56 patients) were included in this study. The subjects consisted of 35 males and 21 females with a mean age of 65 years (range, 46-82). There were 43 large cuff tears (> 3cm in coronal plane) and 13 massive cuff tears (> 5cm). All patients underwent MRI including T2 mapping preoperatively, and T2 values of the supraspinatus (SSP) and infraspinatus (ISP) muscles were quantitatively measured at 15mm medial site from conventional Y-view. ARCRs were performed using suture-bridging techniques in all cases, and the fascia lata was used for patch augmentation in two massive tears. Re-tears were evaluated with MRI at postoperative 1 year according to the Sugaya classification. Preoperative T2 values of the SSP and ISP were compared between shoulders with and without re-tear. Student’s t test was used for comparison of T2 values between the two groups.

Results

Re-tears were found in 18 shoulders (32%), and the re-tear rates were 23% (10/43) in large tears and 62% (8/13) in massive tears. The mean preoperative T2 values of the SSP were 75 ± 10 milliseconds in re-tear shoulders and 65 ± 11 milliseconds in intact shoulders, and the difference was significant (p=0.003). The mean preoperative T2 values of the ISP were 70 ± 19 milliseconds in re-tear shoulders and 56 ± 11 milliseconds in intact shoulders, and the difference was also significant (p=0.001). Although T2 values were < 80 milliseconds in the SSP and < 60 milliseconds in the ISP in 74% of intact shoulders, only 22% of re-tear shoulders had T2 values in these ranges.

Conclusion

The present study revealed that preoperative T2 values of the SSP and ISP muscles in re-tear shoulders were significantly higher than those in intact shoulders. Preoperative T2 values of > 80 milliseconds in the SSP or > 60 milliseconds in the ISP may suggest a high risk of re-tear.