Short-term clinical and radiologic outcomes of reverse total shoulder arthroplasty with navigation system in the Asian population: a retrospective comparative study

Abstract

Background: In reverse total arthroplasty (rTSA), glenoid component positioning is a critical factor for outcomes especially in Asian populations with smaller glenoids. The purpose of this study was to compare the clinical and radiologic outcomes of rTSA with and without the navigation system with a minimum follow-up of 2 years in the Asian population.

Methods: This was a retrospective comparative study of 33 rTSAs with the navigation system (NAV group) and 40 conventional rTSAs (CON group). Radiologic measurements regarding the position of the glenoid component, glenoid vault perforation by the central cage, and scapular notching, as well as clinical outcomes including range of motion, functional scores, and complications were compared. Number, length, and angulation of screws were assessed.

Results: The mean age was 73.9 ± 5.9 years with a mean follow-up of 30.1 ± 6.4 months. The NAV group more frequently utilized augmented baseplate (P < .001), showed less superior inclination (P = .030) and had lower incidence of glenoid vault perforation (P = .040). The length of superior (P = .001) and inferior screws (P = .045) was longer in the NAV group. In the NAV group compared to the CON group, more inferior orientation of superior screws (P < .001), more anterior orientation for inferior screws (P = .031), and anterior screws (P = .003) were observed. The NAV group showed significantly less penetration into the suprascapular fossa by a superior screw (P = .007). Final range of motion, functional scores, and complications showed no significant differences between the 2 groups.

Conclusion: In the short-term follow-up, the use of a navigation system in rTSA showed no significant difference in clinical outcomes and complications compared to conventional implantation. However, it enabled a lower superior inclination and a reduced glenoid vault perforation by the central cage, simultaneously allowing for the insertion of longer peripheral screws in a safer direction compared to conventional implantation.

Keywords: Clinical outcomes; Computer-assisted surgery; Glenoid; Navigation; Radiologic outcomes; Reverse total arthroplasty.

Figure 1

Measurement of screw orientation in 2-month postoperative CT. (a) The superoinferior orientation of screws (), based on the central cage axis (), was measured in the oblique coronal view. Note that positive values indicate a superior direction, while negative values indicate an inferior direction compared to the central cage axis. (b) The anteroposterior orientation of screw (), based on the central cage line (), was measured in the axial view. Note that positive values indicate an anterior direction, while negative values indicate a posterior direction compared to the central cage axis. CT, computed tomography.

Figure 2

Penetration of superior screw into the suprascapular fossa in the oblique coronal and oblique sagittal CT view, two months postoperatively. () indicates the penetration of superior screw into the suprascapular fossa. CT, computed tomography.

Figure 3

A flowchart of patient selection. NAV, navigation reverse total arthroplasty; CON, conventional reverse total arthroplasty.

Figure 4

Scatter plots of screw orientation for the NAV group (left) and CON group (right). The () indicates the center of each screw hole, and the () represents the mean orientation of the screw for each group. Positive values indicate superior direction in the coronal plane, anterior direction in the axial plane, respectively. (a) Superior screw. (b) Inferior screw. (c) Anterior screw. NAV, navigation reverse total shoulder arthroplasty; CON, conventional reverse total shoulder arthroplasty.

Figure 4

Scatter plots of screw orientation for the NAV group (left) and CON group (right). The () indicates the center of each screw hole, and the () represents the mean orientation of the screw for each group. Positive values indicate superior direction in the coronal plane, anterior direction in the axial plane, respectively. (a) Superior screw. (b) Inferior screw. (c) Anterior screw. NAV, navigation reverse total shoulder arthroplasty; CON, conventional reverse total shoulder arthroplasty.