Clinical outcomes of anatomic total shoulder arthroplasty for primary shoulder osteoarthritis did not differ between elderly and younger Japanese patients

BACKGROUND: Few studies on the outcomes of anatomic total shoulder arthroplasty (aTSA) in Asian populations have been reported. In addition, approximately one-third of primary aTSA were performed for patients 80 years or older in Japan, but the indication of aTSA for the primary shoulder osteoarthritis in the elderly population remained unclear. The purposes of this study were (1) to investigate clinical outcomes of aTSA in Japanese patients with primary glenohumeral osteoarthritis and (2) to compare clinical outcomes between patients 80 years or older and 70 years or younger. We hypothesized that aTSA would yield favorable outcomes in Japanese patients and that the outcomes of aTSA in patients 80 years or older would be comparable to those 70 years or younger. METHODS: Patient records were retrospectively reviewed to collect patients who underwent aTSA for glenohumeral osteoarthritis between August 2011 and September 2017. The inclusion criterion of this study was aTSA performed for glenohumeral osteoarthritis. Exclusion criteria were as follows: (1) secondary osteoarthritis, (2) revision surgery, and (3) < 24-month follow-up. Range of motion (ROM) and Constant score were evaluated, and complications were investigated. Rotator cuff integrity was assessed by ultrasonography. We compared the outcomes between patients 80 years or older and 70 years or younger. RESULTS: Seventy-seven shoulders (72 patients) met the study criteria. There were 14 men and 58 women with a mean age of 75 years (range, 57-93 years) at the time of surgery. The mean follow-up was 40 months (range, 24-84 months). The Constant score significantly improved from preoperative 54 (range, 35-78) to postoperative 89 (range 69-100, P = .03). Range of motion also showed significant improvement after surgery: flexion, 90° (range, 60°-130°) to 140° (range, 90°-170°); external rotation at the side, from 7° (range, -10 to 60°) to 40° (range, 5°-70°); internal rotation, from buttock (range, buttock-L3) to L2 level (range, buttock-T8) (P <.001 for all). Postoperative subscapularis tendon tears were detected in 3 shoulders (5%). Complications other than rotator cuff tears were observed in 5 shoulders (6%). Postoperative Constant score and ROM significantly improved in both elderly and younger patients without significant differences. CONCLUSION: The clinical outcomes after aTSA in the Japanese population demonstrated significant improvements in ROM and Constant score with a low complication rate in the mid-term follow-up. aTSA should be indicated even in elderly patients because they also demonstrated comparable outcomes to younger patients.