Impact of surgeon experience on the effectiveness of patient-specific instrumentation in reverse shoulder arthroplasty.

Scapular models were created based on preoperative computed tomography images obtained for 8 cases of cuff tear arthropathy that underwent reverse shoulder arthroplasty (RSA). Four surgeons performed baseplate implantation:A, a shoulder surgeon with experience of more than 200 RSA cases;B, an arthroscopic shoulder surgeon with experience of fewer than 10 RSA cases;C, an orthopedic fellow;and D, an orthopedic resident. Implantation was performed using the conventional method and using patient-specific instrumentation (PSI). Overall, the mean ΔInc was 9.1° using the conventional method and 3.7° using PSI;the respective mean ΔVer were 3.7° and 3.2°. Using the conventional method, there were statistically significant inter-surgeon differences in ΔInc (p=0.038) but not in ΔVer (p=0.77). Using the PSI method, there was no significant inter-surgeon difference in ΔInc (p=0.89) or ΔVer (p=0.23). There was a statistically significant intra-surgeon difference in ΔInc for surgeons B and C (B, p<0.001;C, p=.007) but not in ΔVer for any of the surgeons. PSI ensured the accuracy of baseplate implantation in RSA regardless of a certain amount of surgeon's experience. Implantation accuracy was more impacted when the surgeon was less experienced. J. Med. Invest. 73 : 217-221, February, 2026.