Version and inclination obtained with 3-dimensional planning in total shoulder arthroplasty: do different programs produce the same results?

BACKGROUND

Our purpose was to compare the output of glenoid measurements with 2 commercially available preoperative 3-dimensional (3D) total shoulder arthroplasty planning systems. The hypothesis was that there would be no difference in product-derived measurements between the systems.

METHODS

Preoperative 3D computed tomography scans of 63 consecutive patients undergoing primary arthroplasty were analyzed using 2 product-derived techniques: Blueprint and VIP. Glenoid version and inclination measurements with each system were blinded and statistically compared, and the amount of variance was recorded.

RESULTS

Glenoid version based on Blueprint was -10.9° ± 9.0° (range, -41° to 14°) compared with -9.3° ± 8.2° (range, -36° to 8°) for VIP ( = .04). Inclination was 9.0° ± 8.8° (range, -12° to 29°) with Blueprint compared with 9.7° ± 6.1° (range, -6° to 22°) for VIP ( = .463). For version, the difference between the 2 systems was less than 5° in 44 cases (69.8%), 5°-10° in 12 cases (19.0%), and greater than 10° in 7 cases (11.1%). For inclination, the difference was less than 5° in 34 cases (54.0%), 5°-10° in 17 cases (27.0%), and greater than 10° in 12 cases (19.0%). We found no differences in glenoid version or inclination based on glenoid morphology between the 2 systems ( = .908) and no differences between patients with the most severe arthritis and posterior wear ( = .202).

CONCLUSIONS

There is considerable variability between preoperative measurements obtained for 3D planning of shoulder arthroplasty with the use of Blueprint and VIP. Given that implant choice and desired component positioning are based on preoperative measurements, further study is needed to evaluate the differences between the measurements obtained with different techniques.