Accuracy of patient-specific guided implantation of the glenoid component in reversed shoulder arthroplasty.

BACKGROUND: The aim of this study was to assess the accuracy of patient-specific guided glenoid component implantation in reverse shoulder arthroplasty.

MATERIALS AND METHODS: 32 reverse shoulder arthroplasties were done using preoperative 3D planning and 4 patient-specific guides to prepare the glenoid and position the glenoid component. Baseplate version, inclination and entry point as well as angulation of the screws were compared to the preoperative plan measured on CT by independent observers.

RESULTS: The mean deviation in baseplate version from the preoperative plan was 4.4°+3.1° (range, 0.3°-13.7°), in baseplate inclination 5.0°+4.2° (range, 0.1° to 14.5°) and in baseplate entry point 2.4mm+1.4mm (range, 0.4° to 6.3°). The average screw superior-inferior angulation deviation for the superior screw was 2.8°+2.6° (range, 0.0°-10.1°) and 2.8+2.6° in the antero-posterior plane (range, 0.1°-11.6°). For the inferior screw the superior-inferior angle deviation was 5.3°+3.8° (range, 0.1°-15.2°); the antero-posterior angle deviation was 4.1°+3.1° (range, 0.0°-9.8°).

CONCLUSIONS: Patient-specific instrumentation (PSI) for the glenoid component in reverse shoulder arthroplasty allows the shoulder surgeon to accurately execute the preoperative 3D plan.

LEVEL OF EVIDENCE: Level 3.