Summary

This study evaluated the relationship between repair tension during arthroscopic rotator cuff repair and preoperative MRI findings and retear after surgery. Repair tension was significantly associated with tear size in ML dimension on preoperative MRI and retair after surgery. The AUC curve indicated that repair tension of more than 30N in 30° of abduction increases the risk of retear.

Abstract

Purpose

The tension required to repair the torn tendon influences tendon healing and surgical outcomes of arthroscopic rotator cuff repair. However, little is known about the effect of the repair tension during surgery on the tendon healing after surgery. The purpose of this study was to evaluate the relationship between the repair tension and retear, and if possible, to determine the minimum repair tension to increase the risk of retear. Another purpose was to determine the independent findings on preoperative MRI affecting the repair tension.

Methods

Eighty-eight consecutive shoulders with full-thickness rotator cuff tears treated with the arthroscopic double-row or suture-bridge technique from June 2014 to May 2016 were enrolled in this study. Only shoulders with complete repair coverage of the footprint were included. For measuring repair tension, a tensioning suture was placed through the rotator cuff tendon after mobilization of the rotator cuff. This suture was connected to a sterile tensiometer for measuring the tension in the rotator cuff suture. With the arm placed in 30° of abduction and neutral rotation in the scapular plane, tension was measured when the cuff was properly reapproximated to the footprint. Retear was evaluated according to Sugaya’s classification system on postoperative MRI at 3 months after surgery. Multiple regression analysis was used to determine the independent variables of findings on preoperative MRI affecting repair tension using the stepwise forward method. Receiver operating characteristic (ROC) curve was plotted for repair tension vs. retear, and the area under the ROC curve (AUC) was adopted as a measure to analyze discrimination power, which refers to the ability to distinguish those who have a tear from those who do not. Significance level was set at P < .05 for all the statistical tests performed.

Results

Mean repair tension was 25.9±19.6 N and retear was found in 18 shoulders (20.5%). In the multiple regression analysis, tear size in the coronal plane (standard partial regression coefficient:0.617, p<0.001) and fatty degeneration of the supraspinatus (0.337, p=0.014) were significant factors affecting repair tension. AUC for repair tension was 0.811 (p<0.001), and ROC curve determined 28.9N as a cut-off value for retear.

Conclusions

This study showed that tear size in the coronal plane was most affecting variable on preoperative MRI to affect repair tension during surgery. The AUC indicated that repair tension during surgery had moderate discrimination power for retear after surgery. The ROC curve also suggested that repair tension of more than 30N increases the risk of retear, when the repair tension is measured with the arm placed in 30° of abduction and neutral rotation in the scapular plane.