Previously, we reported that low signal intensity change at a rotator cuff insertion indicated restoration of the rotator cuff after repair at one year postoperatively. Here we report findings in a low signal change group and a no signal change group. We investigated 180 shoulders of 179 patients after rotator cuff repair. We classified the patients into three groups: 109 shoulders with simultaneous rotator cuff low signal intensity changes six months after repair, (6L group); 37 shoulders with simultaneous rotator cuff low signal intensity changes one year after repair (12L group); 34 shoulders with no low signal intensity changes at one year after repair (12H group). UCLA scores were compared between the groups. For configuration evaluation, we estimated thickness of the SSP, ISP, and deltoid muscles, and fatty degeneration of the SSP muscle using Nakagaki's classification. We compared each item at six months and one year postoperatively. Statistical analysis was performed with significance set at 0.05. UCLA scores were more significantly improved at one year postoperatively than at six months ( p<0.01) in all groups. Recovery of the ISP muscle thickness and fatty degeneration were statistically significant in the “6L” group ( p<0.01, p<0.01, respectively). SSP and Deltoid muscle thickness did not show significant change in any group. Based on these results, we believe that low signal intensity changes show recovery of the rotator cuff itself. Low signal intensity changes can be used as an index to judge clinically the presence of on-site rotator cuff healing.
