Patient-specific instrumentation reduces deviations between planned and postosteotomy humeral retrotorsion and height in shoulder arthroplasty

Background: Patient-specific instrumentation (PSI) may potentially improve humeral osteotomy in shoulder arthroplasty. The purpose of this study was to compare the deviation between planned and postosteotomy humeral inclination, retrotorsion, and height in shoulder arthroplasty, using PSI vs. standard cutting guides (SCG). Methods: Twenty fresh-frozen cadaveric specimens were allocated to undergo humeral osteotomy using either PSI or SCG. such that the 2 groups have similar age, gender, and side. Preosteotomy computed tomography (CT) scan was performed and used for the 3-dimensional (3D) planning. The osteotomy procedure was performed using a PSI designed for each specimen or an SCG depending on the group. A postosteotomy CT scan was performed. The preosteotomy and postosteotomy 3D CT scan reconstructions were super-imposed to calculate the deviation between planned and postosteotomy inclination, retrotorsion, and height. Outliers were defined as cases with 1 or more of the following deviations: >5 degrees inclination, >10 degrees retrotorsion, and >3 mm height. The deviation and outliers in inclination, retrotorsion, and height were compared between the 2 groups. Results: The deviations between planned and postosteotomy parameters were similar among the PSI and SCG groups for inclination (P = .260), whereas they were significantly greater in the SCG group for retrotorsion (P < .001) and height (P = .003). There were 8 outliers in the SCG group, compared with only 1 outlier in the PSI group (P = .005). Most outliers in the SCG group were due to deviation >10 degrees in retrotorsion. Conclusion: After 3D planning, PSI had less deviation between planned and postosteotomy humeral retrotorsion and height, relative to SCG. (C) 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.

Automated summary

This study compared the deviation between planned and postosteotomy humeral inclination, retrotorsion, and height in shoulder arthroplasty using patient-specific instrumentation (PSI) vs. standard cutting guides (SCG). The results showed that PSI had less deviation and fewer outliers compared to SCG, indicating the potential of PSI in improving humeral osteotomy.