Short-term functional outcomes of reverse shoulder arthroplasty following three-dimensional planning is similar whether placed with a standard guide or patient-specific instrumentation

Background: Preoperative assessment of the glenoid and surgical placement of the initial guidewire are important in implant positioning during reverse total shoulder arthroplasty (rTSA). Three-dimensional (3D) computed tomography and patient-specific instrumentation (PSI) have improved the placement of the glenoid component, but the impact on clinical outcomes remains unclear. The purpose of this study was to compare short-term clinical outcomes after rTSA based on an intraoperative technique for central guidewire placement in a cohort of patients who had preoperative 3D planning. Methods: A retrospective matched analysis was performed from a multicenter prospective cohort of patients who underwent rTSA with preoperative 3D planning and a minimum of 2-year clinical follow-up. Patients were divided into 2 cohorts based on the technique used for glenoid guide pin placement: (1) standard manufacture guide (SG) that was not customized or (2) PSI. Patient-reported outcomes (PROs), active range of motion, and strength measures were compared between the groups. The American Shoulder and Elbow Surgeons score was used to assess the minimum clinically important difference, substantial clinical benefit, and patient acceptable symptomatic state. Results: One hundred seventy-eight patients met the study criteria: 56 underwent SGs and 122 underwent PSI. There was no difference in PROs between cohorts. There were no significant differences in the percentage of patients who achieved an American Shoulder and Elbow Surgeons minimum clinically important difference, substantial clinical benefit, or patient acceptable symptomatic state. Improvements in internal rotation to the nearest spinal level (P < .001) and at 90° (P = .002) were higher in the SG group, but likely explained by differences in glenoid lateralization used. Improvements in abduction strength (P < .001) and external rotation strength (P = .010) were higher in the PSI group. Conclusion: rTSA performed after preoperative 3D planning leads to similar improvement in PROs regardless of whether an SG or PSI is used intraoperatively for central glenoid wire placement. Greater improvement in postoperative strength was observed with the use of PSI, but the clinical significance of this finding is unclear.