Changes in proximal femoral mineral geometry precede the onset of radiographic hip osteoarthritis: The study of osteoporotic fractures

Abstract

Radiographic hip osteoarthritis (RHOA) is associated with increased hip bone mineral density (aBMD). We examined whether femoral geometry was associated with RHOA independently of aBMD. Participants from the Study for Osteoporotic Fractures (SOF) with pelvis radiographs at visits 1 and 5 (8.3yrs apartt) and hip DXA (2yrs after baseline) were included. Prevalent and incident RHOA phenotypes were defined as composite (osteophytes and joint space narrowing (JSN)), atrophic (JSN without osteophytes) and osteophytic (femoral osteophytes without JSN). Analogous definitions of progression were based on minimum joint space and total osteophyte score. Hip DXA scans were assessed using the hip structural analysis program to derive geometric measures including femoral neck length, width and centroid position. Relative risks (95% CI) for prevalent, incident and progressive RHOA per SD increase in geometric measure were estimated in a hip-based analysis using multinomial logistic regression and adjusting for age, body mass index, knee height and total hip aBMD. In 5245 women (mean age 72.6 yrs), a wider femoral neck with more medial centroid position was associated with prevalent and incident osteophytic and composite RHOA phenotypes (p<0.05). Increased neck width and centroid position were significantly associated with osteophyte progression (both p<0.05). No significant geometric associations were found with atrophic RHOA. Differences in proximal femoral bone geometry and distribution occur early in hip OA and predict prevalent, incident and progressive osteophytic and composite, but not the atrophic, phenotypes. These bone differences may reflect responses to loading occuring early in the natural history of RHOA.

Comparative high-resolution pQCT analysis of femoral neck indicates different bone mass distribution in osteoporosis and osteoarthritis

“…The fact that the trabecular and cortical thickness of the femoral neck, as well as the bone volume and apparent density of the relevant compartments, are negatively correlated in OA supports the view that the modeling process that distributes the bone mass along the femoral neck axis is preserved in this cohort to fulfill mechanical demand [40,41]. A greater resistance to bending is produced by later displacement of the relatively thinner cortex from the neutral axis [42], and a thick cortical shell is preferred over a dense trabecular core for bone strength at the femoral neck, as shown by strain distribution analysis with micro-finite element models [32].…”

Osteoarthritis and bone mineral density: are strong bones bad for joints?

“…43 DXA scans measure areal BMD, which is affected by bone size. 44,45 Larger bones have increased volume in relation to their area; therefore, dividing bone mineral content by bone area to obtain apparent areal BMD will lead to an overestimation of BMD proportional to size. This is relevant, because several studies have observed increases in bone size in individuals with OA, both local to [44][45][46] and distant from 47 the affected joint.…”

Relationship between joint shape and the development of osteoarthritis

“…At least two studies have identified a widened femoral neck as associated with hip osteoarthritis [47,48]. Javaid and colleagues [47] examined 5245 elderly Caucasian women in the study of osteoporotic fractures (mean age 72.6 years) with mean follow-up of 8.3 years and found that a wider femoral neck was associated with both prevalent and incident cases of radiographic hip osteoarthritis.…”