Radiographic osteoarthritis of the hip and bone mineral density

Abstract

Objective. To examine the cross-sectional association between radiographic features of hip osteoarthritis (OA) and bone mineral density (BMD) of the hip, spine, and appendicular skeleton among Caucasian women ages 65 and older who were participating in the Study of Osteoporotic Fractures.Methods. Pelvis radiographs of 4,855 subjects were assessed for individual radiographic features of hip OA: osteophytes, joint space narrowing, subchondral sclerosis, cysts, and femoral head deformity. Hips were graded on a summary scale of 0 (no OA) to 4 (severe OA) based on the number of radiographic features present. Appendicular BMD was measured in all subjects, and hip and spine BMD in 84% of the group. We used linear regression to examine the association of BMD with hip OA, and to adjust for age, weight, and other determinants of bone mass.Results. Three hundred fifty-one women (7.2%) had mild (grade 2) and 228 (4.7%) had moderate to severe (grade 3-4) radiographic evidence of hip OA. Women with grade 3 4 hip OA had a higher ageadjusted BMD at the femoral neck and Ward's triangle (%lo%; P < O.OOOl), trochanter (4%; P < 0.01), lumbar spine (8%; P C O.OOOl), and distal radius and calcaneus (5%; P < 0.0001 [for each comparison]) compared with those with grade 0-1 OA in the worse hip. Elevations in BMD were greatest in the femoral

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

“…The hip and knee joints have been most studied, with several groups finding evidence of higher systemic BMD in those with OA at these joint sites in a variety of populations. [7][8][9][10][11] Higher BMD has also been reported in association with OA of the spine 10,12 and hand. 9,10,13 A limitation of cross-sectional studies is that the direction of causality cannot be formally assessed.…”

“…14,15 It is therefore worth noting that strong positive associations between hip BMD and large joint OA have been observed in many studies, 8,10,11 and that the positive association between lumbar spine BMD and OA at both the hip and knee has been shown to persist after adjusting for the presence of spinal osteophytes. 7,10 More recently, the temporal relationship between BMD and OA has been clarified in prospective studies ( Table 2). Several longitudinal studies have shown higher BMD to be associated with a greater risk of developing subsequent radiographic knee OA, [16][17][18][19][20] although findings have not always been conclusive.…”

“…23,24 In studies in which these individual radiographic features of OA have been quantified separately, increased BMD has generally been reported to be more strongly associated with osteophytosis than JSN. 7,17,18,21 Indeed, only one longitudinal study to date has convincingly demonstrated a positive association between BMD and incident JSN at the knee. 19 Several possible explanations for this observation, both methodological and biological, can be postulated.…”

“…Alternatively, it may be that individuals with high BMD are prone to develop either osteophytes alone (the clinical relevance of which is uncertain) or a hypertrophic phenotype of OA characterised by vigorous osteophytosis; the term 'bone-formers' has been coined to describe this. 3,7,25 The former hypothesis that osteophytes and JSN may have different relationships with BMD is made plausible by the observation that these two features appear to be associated with distinct genetic variants. 26,27 Interestingly, several recent studies using magnetic resonance imaging have actually reported a positive association between BMD and cartilage thickness/volume at the knee in healthy subjects, [28][29][30] raising the possibility that measurable cartilage loss could appear later on in the OA disease trajectory in individuals with higher BMD.…”

“…32 Relatively few studies have examined the relationship between BMD and clinically relevant OA, although it has been reported that individuals with radiographic OA have similar degrees of BMD elevation independent of the presence of joint symptoms. 7,10 Controversies and Inconsistencies Despite the weight of evidence that systemic BMD and radiographic OA are positively associated, some inconsistencies and areas of controversy remain. Cross-sectional investigations into the relationship between OA and bone turnover, which is generally inversely related to BMD owing to its role in bone loss, 33 have yielded conflicting findings.…”