Errors in implant orientation estimation in novice vs. experienced surgeons during reverse shoulder arthroplasty for a superior glenoid wear pattern.

BACKGROUND

Glenoid baseplate orientation in reverse shoulder arthroplasty influences clinical outcomes, complications, and failure rates. This study aimed to determine novice and experienced shoulder surgeon's ability to accurately characterize glenoid component orientation in an intraoperative scenario.

METHODS

Glenoid baseplates were implanted in 8 fresh frozen cadavers by novice surgical trainees. Glenoid baseplate version, inclination, augment rotation, and superior-inferior center of rotation offset were then measured using in-person visual assessments by novice and experienced shoulder surgeons immediately after implantation. Glenoid orientation parameters were then measured using 3-dimensional (3D) computed tomography (CT) scans with digitally reconstructed radiographs (DRRs) by 2 independent observers with a 1-month time interval between repeat measurements. Bland-Altman plots were produced to determine the accuracy of glenoid orientation using standard intraoperative assessment compared to postoperative 3D CT scan results. Interclass correlation coefficients were produced for measurements, rated as 0.01-0.39 poor, 0.40-0.59 fair, 0.60-0.74 good, and 0.75-1.00 excellent.

RESULTS

Visual assessment of glenoid baseplate orientation showed "poor" to "fair" correlation to 3D CT DRR measurements for both novice and experienced surgeon groups for all measured parameters. There was a large discrepancy between intraoperative visual assessments and 3D CT DRR measurements for all parameters. Errors in visual assessment of up to 20° of inclination by experienced surgeons ( = .03), and 8 mm supero-inferior center of rotation offset by novice surgeons ( = .50) occurred. Experienced surgeons had greater measurement error than novices for all measured parameters.

CONCLUSION

Intraoperative measurement errors in glenoid placement are present for both inexperienced and experienced surgeons. Kinesthetic input during implantation may improve orientation understanding.