Proximal Humeral Fat Fraction is Linearly Related to Its Bone Mineral Density

Background: Previous studies have indicated that the fat fraction of bone can reflect bone quality. The purpose of this study is to discuss the relationship between the fat fraction of the proximal humerus and its bone density in patients with rotator cuff tears. Methods: All patients with rotator cuff tears from the same institution between December 1 and December 31, 2023, were included. Bone density was measured using dual-energy X-ray absorptiometry (DXA), and fat fraction data were measured using MRI. The fat fraction data of the regions of interest (a, b, c) in the proximal humerus were analyzed for correlation with their own bone density and lumbar spine bone density. Results: The study included 64 patients. The fat fraction in region a was significantly higher than that in regions b and c, with region c having the lowest fat fraction. The fat fraction of the regions of interest in the proximal humerus showed a linear relationship with both lumbar spine bone density and their own bone density. Conclusions: This study designed a method to measure the fat fraction of the proximal humerus using MRI and found a negative correlation between the fat fraction of the proximal humerus and its own bone density. Level of evidence: Ⅲ