Short term Functional Outcomes of Reverse Shoulder Arthroplasty Following Three-Dimensional Planning is Similar Whether Placed with a Standard Guide or Patient Specific Instrumentation (PSI).

Abstract

Preoperative assessment of the glenoid and surgical placement of the initial guide wire are important in implant positioning during reverse total shoulder arthroplasty (rTSA). Three-dimensional (3D) computed tomography (CT) 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 intraoperative technique for central guidewire placement in a cohort of patients that had preoperative 3D planning. 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 utilized 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 (ROM), and strength measures were compared between the groups. The ASES score was used to assess the minimum clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS). One hundred seventy patients met the study criteria, including 56 performed with SGs and 122 with PSI. There was no difference in PROs between cohorts. There were no significant differences in the percentage of patients that achieved an ASES MCID, SCB, or PASS. Improvement in internal rotation to the nearest spinal level (p < .001) and at 90° (p = .002) were higher in the SG group and, but likely explained by differences in glenoid lateralization utilized. Improvement in abduction strength (p < .001) and external rotation strength (p = .010) were higher in the PSI group. rTSA performed following preoperative 3D planning leads to similar improvement in PROs regardless of whether a SG or PSI are utilized 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.