CORR Insights^®: Patients With Hip Osteoarthritis Have a Phenotype With High Bone Mass and Low Lean Body Mass

Excerpt

Patients with osteoarthritis generally are more obese, have bigger body frames, and have higher bone mass than their peers without osteoarthritis [3]. Body mass index (BMI, in kg/m²) is the most common surrogate of overweight or obesity in clinical studies. However, for any individual patient, sole BMI can be a misleading trait, as it is unable to distinguish between the contribution of fat and muscle tissues to the total body weight. Paradoxically, BMI is higher for a muscular people of otherwise similar body heights and volumes, possibly giving an illusion of obesity. Also, mean BMI is higher among taller people (men versus women). Another commonly used clinical trait in osteoarthritis studies, dual-energy x-ray absorptiometry (DXA)-measured areal bone mineral density, can be fallacious as well. Areal bone mineral density depends on the volumetric bone mineral, apparent density, and bone size. However, it is unable to separate the influence of these factors from each other, nor capable of capturing structural traits or mechanical properties of given bone [8]. Additionally, the accuracy of areal bone mineral density can be severely compromised because of subject-specific anatomy and distribution of soft tissues, consequently violating the assumptions inherent in DXA [2]. Both BMI and areal bone mineral density are too nonspecific and ambiguous for phenotyping individual patients against a well-defined and specific diagnosis like hip osteoarthritis. …