SRS117 - Factors influencing the use of patient-specific instrumentation in shoulder arthroplasty

Abstract Introduction Patient Specific Instrumentation (PSI) has become a valuable tool in shoulder arthroplasty, especially for glenoid component placement. This study aimed to identify key factors influencing PSI use in shoulder arthroplasty. Methods A retrospective analysis of 191 anatomic and reverse total shoulder arthroplasty (aTSA, rTSA) cases performed between 2021–2024 by two senior upper limb consultants at The Royal Wolverhampton NHS Trust. All procedures used the Zimmer Biomet system with pre-operative planning via Signature ONE software. Recorded parameters included patient demographics, surgical side, glenoid anteroposterior (AP) diameter, vault depth, retroversion, and superior inclination. Statistical analysis was conducted using SPSS (V16). Results PSI was used in 64.7% (101/156) of rTSA cases and 42.9% (15/35) of aTSA cases. No significant association was found between PSI usage and age, sex, or surgical side. Increased glenoid retroversion (Median [IQR] 9.5 [5–13.87]) and superior inclination (96.75 [3.62–12.37]) were significantly associated with PSI use (P < 0.05). Although reduced glenoid AP diameter and vault depth showed a trend towards PSI use, they were not statistically significant (AP diameter: P = 0.824; vault depth: P = 0.282). PSI was significantly more likely in cases requiring medium (86.9%) or large (58.9%) glenoid augments (P < 0.001), facilitating the use of a larger central screw (≥30 mm) in 86.6% of cases. Conclusions PSI use in shoulder arthroplasty is primarily influenced by glenoid morphology, particularly retroversion, superior inclination, and augmentation requirements. Its application enhances intra-operative precision and may support improved fixation in anatomically complex cases.