Title : Decision making in selecting Patient Specific Instrumentation (PSI) for Shoulder Arthroplasty (SA)
Abstract:
Introduction: Patient Specific Instrumentation (PSI) has emerged as a valuable aid in shoulder arthroplast, particularly for placement of the glenoid component. This study aimed to identify the key factors which influenced the decision to use PSI in shoulder arthroplasty.
Methods: A retrospective analysis of 191 anatomic and reverse total Shoulder Arthroplasty (aTSA, rTSA) cases performed between 2021 and 2024 by two senior upper limb consultants at The Royal Wolverhampton NHS Trust. All procedures utilised the Zimmer Biomet system with pre-operative planning via Signature one Software. The parameters recorded included patient demographics, side of surgery, glenoid anteroposterior (AP) diameter, vault depth, retroversion and superior inclination. Statistical Analysis was subsequently performed using SPSS (V16).
Results: PSI was used in 64.7% (101/156) of rTSA cases and 42.9% (15/35) aTSA cases. There was no significant association found between PSI usage and patient age, sex, or side of surgery. 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 decreased anteroposterior (AP) glenoid 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 to be used in cases requiring medium (86.9%) or large (58.9%) glenoid augments (p<0.001), which facilitated the use of a larger central screw (≥30 mm) in 86.6% of cases.
Conclusion: The use of PSI in shoulder arthroplasty is primarily driven by glenoid morphology, particularly retroversion, superior inclination and the need for augmentation. Its application enhances intraoperative execution and may support improved implant fixation in anatomically challenging cases, however further study.
