Predictors of total hip replacement in community based older adults: a cohort study.

OBJECTIVE: The purpose of this study is to describe predictors of total hip replacement (THR) in community dwelling older adults. A better understanding of predictors of THR can aid in triaging patients and researching preventative strategies. DESIGN: At baseline, participants had assessment of radiographic OA and cam morphology (from pelvic radiographs), shape mode scores and hip bone mineral density (BMD; from dual energy X-ray absorptiometry (DXA)). After 2.6 and 5 years, participants reported hip pain using WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index), and had hip structural changes assessed using magnetic resonance imaging (MRI). Risk of THR was analysed using mixed-effect Poisson regression. RESULTS: Incidence of THR for OA over 14 years was 4.6% (37/801). As expected, WOMAC hip pain and hip radiographic OA both predicted risk of THR. Additionally, shape mode 2 score (decreasing acetabular coverage) (RR 1.83/SD; 95% CI 1.1-3.04), shape mode 4 score (non-spherical femoral head) (RR 0.59/SD; 95% CI 0.36-0.96), cam morphology (α > 60°) (RR 2.2/SD; 95% CI 1.33-3.36), neck of femur BMD (RR 2.09/SD, 95% CI 1.48-2.94) and bone marrow lesions (BMLs) increased risk of THR (RR 7.10/unit; 95% CI 1.09-46.29). CONCLUSION: In addition to hip pain and radiographic hip OA, measures of hip shape, cam morphology, BMD and BMLs independently predict risk of THR. This supports the role of hip bone geometry and structure in the pathogenesis of end stage hip OA and has identified factors that can be used to improve prediction models for THR.

Does obesity affect knee cartilage? A systematic review of magnetic resonance imaging data.

There is increasing evidence for the effect of obesity on knee osteoarthritis (OA), although the association between obesity, particularly body composition, and knee osteoarthritis, using magnetic resonance imaging (MRI) to examine knee structure, has not been examined. We systematically evaluated the evidence for the relationship between obesity and knee cartilage assessed by MRI. We performed an electronic search of MEDLINE and EMBASE up to December 2012. Included studies investigated the association between obesity and the development and/or progression of knee cartilage changes using MRI. The studies were ranked according to their methodological score and best-evidence synthesis was performed to summarize the results Twenty-two studies were identified for inclusion, of which 7 were cross-sectional, 13 were longitudinal and 2 had both cross-sectional and longitudinal components. Seven cross-sectional and eight longitudinal studies were of high quality. Best-evidence synthesis showed consistent, yet limited evidence for a detrimental effect of body mass index (BMI) and fat mass on knee cartilage. This review identified a consistent detrimental effect of obesity, particularly related to elevated BMI and fat mass on cartilage defects. The strength of evidence was limited by the paucity of high-quality cohort studies examining this question. By further examining the mechanisms for these different effects, new strategies can be developed to prevent and treat knee OA.