Summary

Lower Cortical Core Thickness and Bone Mineral Density Does Not Lead to Inferior Outcomes after Reverse Shoulder Arthroplasty

Abstract

Purpose

To study the influence of combined cortical thickness (CCT) (as a surrogate of bone mineral density) of the proximal humerus on reverse shoulder arthroplasty (RSA) outcomes.

Methods

The study included 113 patients who underwent RSA for various indications. Patients were evaluated postoperatively at 3, 6, 12, and 24 months. An independent reviewer measured CCT on preoperative radiographs. Functional outcome of the surgery was assessed with the Constant shoulder score (CSS), University of California at Los Angeles Shoulder rating scale (UCLASS), Oxford shoulder score (OSS), Visual Analogue Scale (VAS), Satisfaction score (SAT) and range of motion of forward flexion (ROM-FF) and abduction (ROM-ABD). The patients were divided based on CCT: >3.8mm (higher CCT) and <3.8 mm (lower CCT). Wilcoxon U test was used to compare continuous variables between the two groups, and multivariate linear regressions were applied to study the effect of higher CCT on functional scores.

Results

Low BMD patients comprised 87.9% of the group. Differences in outcomes at 2 years follow up for the CSS (P = 0.929), OSS (P = 0.429), UCLASS (P = 0.802), ROM-FF (P = 0.841), ROM-ABD (P = 0.633), VAS (P = 0.477), and SAT (P = 0.801) were not significant. Differences at shorter time intervals were not significant either. Complication rate was low, with no fracture complications, 1 case of dislocation and 21% rate of notching.

Discussion

Lower bone mineral densities predispose to fracture complications after reverse shoulder arthroplasty. In the absence of such complications, lower CCT does not lead to lower outcome scores.