Early clinical outcomes following navigation-assisted baseplate fixation in reverse total shoulder arthroplasty: a matched cohort study

Accurate placement of the glenoid baseplate is an important technical goal of reverse total shoulder arthroplasty (RSA). The use of computer navigated instrumentation has been shown to improve the accuracy and precision of intraoperative execution of preoperative planning. The purpose of this study was to compare early clinical outcomes of patients undergoing navigated RSA vs. a non-navigated matched cohort. A retrospective review of a prospectively collected shoulder arthroplasty database was used to identify 113 patients from a single institution who underwent navigated primary RSA with a minimum 2-year follow-up. A matched cohort of 113 non-navigated RSAs was created based on sex, age, follow-up, and preoperative diagnosis. Preoperative and postoperative range of motion, functional outcome scores, and complications were reported. A total of 226 shoulders with a mean age of 71 years were evaluated after navigated (113) or non-navigated (113) RSAs. The mean follow-up was 32.8 months (range: 21-54 months). At the final postoperative follow-up, the navigated group had better active forward elevation (135° vs. 129°, P = .023), active external rotation (39° vs. 32°, P = .003), and Constant scores (71.1 vs. 65.5, P = .003). However, when comparing improvements from the preoperative state, there was no statistically significant difference in range of motion or functional outcome scores between the groups. Complications occurred in 1.8% (2) of patients undergoing navigated RSA compared with 5.3% (6) in the non-navigated group (P = .28). Scapular notching (3.1% vs. 8.0%, P = .21) and revision surgery (0.9% vs. 3.5%, P = .37) were more common in non-navigated shoulders. At early follow-up, navigated and non-navigated RSAs yielded similar rates of improvement in range of motion and functional outcome scores. Notching and reoperation was more common in non-navigated shoulders, but did not reach statistical significance. Longer follow-up and larger cohort size are needed to determine if intraoperative navigation lengthens the durability of RSA results and reduces the incidence of postoperative complications.