Irreparable rotator cuff tears (IRCT) have led to a variety of treatment recommendations. The purpose of this retrospective study was to assess the clinical outcomes of partial repair of infraspinatus tendon transfer for IRCT. We reviewed the result of partial repair of IRCT in 19 patients (15 males, 4 females). The mean age at operation was 64 years (53-76), and the mean follow-up period was 22 months (12-45). We performed partial repair of infraspinatus tendon transfer after acromioplasty and synovectomy by mini-open method. The clinical assessment included JOA score, UCLA score and isometric power (abduction and external rotation by degree less than the unaffected side) at final follow-up. In addition, pre- and postoperative (avg. 16 months) fatty degeneration of the rotator cuff musculature was estimated according to the Goutallier grading system. Statistical analysis of data was performed using χ2 test and Mann-Whitney U test. Significant differences were present between average pre- (53.1 and 16.5) and postoperative (84.9 and 28.0) in JOA and UCLA score, respectively (p<0.01). There were significant differences in isometric powers between pre- (abduction 26.6% and external rotation 35.6%) and postoperative power (53.3 and 58.3%), respectively (p<0.05). Therefore the preoperative average stage of supraspinatus muscle (1.9, range 0-3) progressed more than the postoperative muscle (2.6, range 1-4) (p<0.05). However there were no significant differences in the average stage of infraspinatus muscle between preoperative (1.5, range 0-3) and postoperative (1.8, range 0-3) grading system. Partial repair of IRCT can provide significant clinical and functional improvement. However, postoperative fatty degeneration of supraspinatus musculature progressed more than preoperative, and fatty degeneration of infraspinatus musculature kept preoperative status.
