High bone mass is associated with an increased prevalence of joint replacement

Numerous epidemiological studies have reported an association between osteoarthritis and increased bone mineral density (BMD). To explore the nature of this association we examined whether osteoarthritis risk is increased in individuals with high bone mass (HBM), in whom bone mineral density is assumed to be elevated due to a primary genetic cause.

335 115 dual x-ray absorptiometry (DXA) scans were screened to identify HBM index cases (defined by DXA scan as an L1 Z-score of ≥+3·2 and total hip Z-score ≥+1·2 or total hip Z-score ≥+3·2 and L1 Z-score ≥+1·2). In relatives, the definition of HBM was L1 Z-score plus total hip Z-score ≥+3·2. Controls comprised unaffected relatives and spouses. Clinical indicators of osteoarthritis were determined by structured assessment. Analyses used logistic regression adjusting for age, gender, and body-mass index.

353 individuals with HBM (mean age 61·7 years, 77% female) and 197 controls (mean age 54·1 years, 47% female) were included. The prevalence of prior joint replacement surgery was higher in HBM cases (13·0%) than in controls (4·1%) (adjusted odds ratio 2·42 [95% CI 1·06–5·56], p=0·04). Adjusted use of non-steroidal anti-inflammatory drugs (NSAIDs) was also more prevalent in HBM cases than in controls (odds ratio 2·17 [1·10–4·28], p=0·03). Adjusted prevalence of joint pain and knee crepitus did not differ between cases and controls. Further comparison of unadjusted joint replacement prevalence in HBM cases aged 65 years or older with equivalent population data from the Health Survey for England 2005 also suggested an increase in joint replacement in HBM.

Individuals with HBM have a higher prevalence of joint replacement and NSAID use compared with controls, suggesting an association between HBM and osteoarthritis.

Arthritis Research UK, Wellcome Trust, and National Institute for Health Research.