Interest in computer-assisted surgery on the glenoid implant positioning in the context of navigated or planned total shoulder arthroplasties.

Background: Three-dimensional planning and intraoperative navigation are beneficial for glenoid implant positioning in total shoulder arthroplasty (TSA). The respective benefits of these two techniques are still being evaluated. The aim of this study was to evaluate the contribution of intraoperative navigation to glenoid implant positioning, compared with planning alone. Our hypothesis is that the use of intraoperative navigation can help to come closer to the planned positioning of the implant, compared with standard instrumentation. Methods: This monocentric, ongoing study included 205 shoulders (197 patients) operated between 2018 and 2024 for a TSA, anatomic or reverse. All patients benefited from preoperative planning (Equinoxe Planning App; Exactech, Gainesville, FL, USA), enabling the collection of native glenoid parameters. Postoperatively, these were assessed using the same method via the planning software. One hundred fifty-three TSA were included, and we identified 2 groups: 101 navigated TSA (navigated planned arthroplasties [NAV] group) and 52 planned TSA (planned arthroplasties [PLA] group), comparable in all respects (68% women, mean age 72.5 years). Version and inclination were compared, as well as the difference between planned and postoperative. Results: The average native glenoid parameters measured and planned were similar between the two groups. The average postoperative version was respectively -2.5° (±4.7°) vs. -1.6° (±6.2°) in the NAV group (P = .259), and the postoperative inclination was respectively 3.8° (±4.9°) vs. 2.0° (±8.1°) in the NAV group (P = .312). The average postoperative deviation from planning in version was 3.0° (±2.9°) in the NAV group vs. 3.7° (±3.0) (P = .157). Regarding inclination, the mean deviation was 4.2° (±3.5°) vs. 6.5° (±5.1°) in the PLA group (P = .004). There was a reduction in the proportion of mispositioned implant in the NAV group, both in version (6.9% vs. 13.5%) and in inclination (9.9% vs. 19.3%). In the revered TSA subgroup, we found a significant reduction of the postoperative deviation from planning in the NAV group. Discussion: Our study highlights the benefits of preoperative planning. We found a reduction in the deviation from planning for reverseTSA, as well as a reduction in the proportion of mispositioned implants. Our series is limited by the absence of randomization. Further studies are needed on clinical improvement after navigation-assisted surgery.