Does magnetic resonance imaging appearance of supraspinatus muscle atrophy change after repairing rotator cuff tears?

Background This study was conducted to determine whether supraspinatus muscle atrophy appearance changes after arthroscopic rotator cuff repair and to quantify the change in appearance on magnetic resonance imaging (MRI), if any, based on age and tendon retraction. Methods We retrospectively reviewed patients who underwent arthroscopic rotator cuff repair and considered only 209 patients who had both preoperative and immediate postoperative MRI. Patients were grouped by age 60 years. They were further subdivided into stage 1 (mild), stage 2 (moderate), and stage 3 (severe), depending on preoperative supraspinatus tendon retraction on the coronal view of MRI according to Patte classification. The postoperative occupancy ratio was compared with the preoperative occupancy ratio within the subgroups, and change in the occupancy ratio was used for comparison between the subgroups. Results There was a significant increase in the occupancy ratio in the mild ( P =.001) and moderate-severe ( P =.003) subgroup from their preoperative values. In the mild subgroup, the occupancy ratio was significantly greater in the group aged 60 years ( P = .010). But in the moderate subgroup there was no significant difference between the 2 age groups ( P = .710). Conclusions A significant change in supraspinatus muscle atrophy occurs in every patient, provided the patient has some tendon retraction preoperatively. The amount of change in supraspinatus muscle atrophy after surgery depends on the age to some extent, but tendon retraction is the most important thing that decides how much change in atrophy can occur postoperatively.