Patients With Hip Osteoarthritis Have a Phenotype With High Bone Mass and Low Lean Body Mass

Abstract

Background Although hip osteoarthritis (OA) is common, its etiology is poorly understood. Specifically, it is not known whether hip OA is associated with abnormal relationships among the anthropometric and musculoskeletal characteristics that are associated with OA in general. Questions We asked whether patients with primary hip OA have a phenotype with higher bone mineral density (BMD), higher BMI, larger skeletal size, lower lean body mass, and higher fat content. Material and Methods We included 30 women and 32 men (mean age, 66 years; range, 42-84 years) with primary hip OA and 96 women and 91 men as control subjects. Dual energy x-ray absorptiometry was used to measure total body BMD (g/cm 2 ), femoral neck width (cm), fat and lean mass (%), and BMI (kg/m 2 ). Z scores were calculated for each individual. Data are presented as means with 95% CI. Results Women with hip OA had the following Z scores: total body BMD 0.6 (0.3, 1.0); BMI 0.6 (0.2, 1.0); femoral neck width 0.2 (À0.6, 1.0); percent total body lean mass À0.9 (À1.2, À0.5); and percent total body fat mass 0.6 (0.2, 0.9). Men with hip OA had the following mean Z scores: total body BMD 0.5 (0.0, 1.0); BMI 0.8 (0.3, 1.3); femoral neck width 0.4 (0.01, 0.9); percent total body lean mass À0.8 (À1

Association between body composition and osteoarthritis: A systematic review and meta‐analysis

“…One cross‐sectional study showed that both the fat mass (OR = 1.69, 95% CI: 1.07‐2.66 for men per SD; OR = 1.67, 95% CI: 1.07‐2.62 for women per SD) and fat mass percentage (OR = 1.87, 95% CI: 1.09‐3.21 for men per SD; OR = 1.87, 95% CI: 1.11‐3.15 for women per SD) were positively associated with hip OA . One cohort study reported that fat mass could increase the risk of developing hip OA (RR = 1.29, 95% CI: 1.18‐1.41).…”

“…Then, full articles were extracted for further assessment after reviewing the titles and abstracts. Eventually, 19 studies (10 cross‐sectional, 5 case‐control and 4 cohort studies) were included in the present systematic review and meta‐analysis. The study screening process is shown in Figure , and the study characteristics and NOS score of the 19 included articles are shown in Table .…”

Patients With Knee Osteoarthritis Have a Phenotype With Higher Bone Mass, Higher Fat Mass, and Lower Lean Body Mass

“…Again, this study can only show an association between knee OA and the studied variables, does not imply causation, and should therefore be regarded as hypothesis-generating. Studies suggest that OA and osteoporosis are distinct different diseases [9] and an association between OA in the hip, knee, ankle, and feet and a high BMD has also been found [3,4,6,8,13,17,20,23]. It has been speculated that a high BMD may result in a denser and stiffer skeleton with less load absorptive ability, a phenotype that may be involved in the pathogenesis of primary OA [25].…”

“…Primary OA leads to local effects on the skeleton, including cysts, subchondral sclerosis, and osteophytes [12]; however, OA is also associated with high bone mineral density (BMD) [3,8,11,17,26,27], high BMI [15,26], and small bone size [8]. It is unclear whether this phenotype is found in all patients with OA, irrespective of the affected joint.…”

“…Previous studies have suggested that high BMI is associated with knee OA but not hip OA and with progression of knee OA but not of hip OA [15,26]. We recently studied this topic for patients with hip arthritis [17]; however, it is important to evaluate it for knee OA separately, because primary OA in different joints may have a different phenotype and thus have different pathophysiological pathways. For example, high body fat is more strongly associated with knee OA than with hip OA [21].…”