Prevalence of radiographic hip osteoarthritis is increased in high bone mass

Abstract

SummaryObjectiveEpidemiological studies have shown an association between increased bone mineral density (BMD) and osteoarthritis (OA), but whether this represents cause or effect remains unclear. In this study, we used a novel approach to investigate this question, determining whether individuals with High Bone Mass (HBM) have a higher prevalence of radiographic hip OA compared with controls.DesignHBM cases came from the UK-based HBM study: HBM was defined by BMD Z-score. Unaffected relatives of index cases were recruited as family controls. Age-stratified random sampling was used to select further population controls from the Chingford and Hertfordshire cohort studies. Pelvic radiographs were pooled and assessed by a single observer blinded to case-control status. Analyses used logistic regression, adjusted for age, gender and body mass index (BMI).Results530 HBM hips in 272 cases (mean age 62.9 years, 74% female) and 1702 control hips in 863 controls (mean age 64.8 years, 84% female) were analysed. The prevalence of radiographic OA, defined as Croft score ≥3, was higher in cases compared with controls (20.0% vs 13.6%), with adjusted odds ratio (OR) [95% CI] 1.52 [1.09, 2.11], P = 0.013. Osteophytes (OR 2.12 [1.61, 2.79], P < 0.001) and subchondral sclerosis (OR 2.78 [1.49, 5.18], P = 0.001) were more prevalent in cases. However, no difference in the prevalence of joint space narrowing (JSN) was seen (OR 0.97 [0.72, 1.33], P = 0.869).ConclusionsAn increased prevalence of radiographic hip OA and osteophytosis was observed in HBM cases compared with controls, in keeping with a positive association between HBM and OA and suggesting that OA in HBM has a hypertrophic phenotype.

High Bone Mass is associated with bone-forming features of osteoarthritis in non-weight bearing joints independent of body mass index

“…We have shown an increased prevalence of radiographic features of OA in non-weight-bearing joints of the hand, amongst HBM individuals compared with family controls, similar to that we previously identified in the weight-bearing joints of the knee and hip [9], [10]. As we had hypothesized, osteophyte measures were more strongly and consistently associated with HBM, than was JSN, consistent with a ‘bone-forming’ phenotype of OA, again in line with our findings at the larger joints [9], [10].…”

“…Obesity is an established risk factor for OA, particularly in large weight-bearing joints; increased mechanical load is considered deleterious to joints [12], [15]. However, although greater BMI contributed in part to the association we observed between HBM and knee OA, the association persisted after BMI adjustment [10], and the relationship between HBM and hip OA appeared independent of BMI [9].…”

“…We have found that HBM individuals have a higher prevalence of self-reported joint replacement and use of non-steroidal anti-inflammatory drugs (NSAIDs) compared with family controls [8]. An increased prevalence of radiographic hip OA was also observed in HBM individuals, particularly with respect to bony features such as osteophytosis and subchondral sclerosis, whereas little evidence was seen for features reflecting cartilage loss such as joint space narrowing (JSN) [9]. Further characterisation of knee OA revealed a similar, osteophyte predominant, radiographic OA phenotype [10].…”

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

“…60 However, although greater BMI appeared to contribute to the association between HBM and knee OA, this association persisted after BMI adjustment, 59 and the relationship between HBM and hip OA appeared to be independent of BMI. 58 It should also be noted that although the HBM cases within this population displayed several clinical features suggestive of a mild skeletal dysplasia, no evidence was found of any significant gait abnormality compared with controls. 56 We speculate that HBM individuals manifest a 'bone-forming' tendency, which contributes to their risk of OA.…”

“…In line with findings in the general population with respect to BMD, the hip OA phenotype in HBM was characterised by bony features such as osteophytosis and subchondral sclerosis. 58 In contrast, when the individual radiographic features of OA were analysed separately, there was little evidence that HBM is associated with JSN. As HBM is associated with an increased prevalence of clinical OA (as demonstrated by our finding of higher rates of joint replacement 58 ), this may imply an association between isolated osteophytosis and clinical symptoms such as pain in this population.…”