Volumetric bone mineral density of the tibia is not increased in subjects with radiographic knee osteoarthritis.
ABSTRACT Radiographic osteoarthritis (ROA) has previously been shown to be associated with an increase in areal bone mineral density (BMD) as assessed by dual energy X-ray absorptiometry (DXA). Here we have assessed volumetric bone density, size and strength by peripheral quantitative computed tomography (pQCT) in a large population-based cohort study in which knee radiographs were available.
Two hundred and ninety-five men and 288 women from the MRC Hertfordshire Cohort Study underwent weight bearing extended knee X-rays and bone density measurement of the ipsi-lateral knee using pQCT.
Increasing radiographic grade in men but not women was associated with an increase in tibial total area at 38% site and cortical area at 14% site, but not with volumetric BMD. The tibial fracture loads as well as tibial polar strength strain index at 38% site were also increased. There were no significant associations of tibia bone area, BMD or strength with radiographic grade in women.
ROA is not associated with an increase in volumetric BMD as assessed by pQCT. It is, however, associated with a significant increase in bone area and strength, indicating that the association between ROA and areal BMD is mediated through bone size rather than volumetric BMD.
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ABSTRACT: The effect of lumbar osteoarthritis on bone density and trabecular bone score (TBS) was evaluated cross-sectionally and prospectively in postmenopausal women. Lumbar spine osteoarthritis was graded according to Kellgren and Lawrence grades. Lumbar osteoarthritis was found to increase lumbar spine bone density, but not TBS. Lumbar osteoarthritis overestimates lumbar bone density (areal bone mineral density (aBMD)). A new texture parameter, the TBS, has been proposed. Calculation of aBMD uses grey level value, while TBS uses grey level variation. Therefore, our hypothesis was that TBS is not influenced by lumbar spine osteoarthritis. Menopausal women participating in osteoporosis and ultrasound (OPUS) study were included. They had an aBMD measurement of the spine and hip at baseline and 6-year visit. TBS was calculated on lumbar spine dual-energy X-ray absorptiometry (DXA) scans in an automated manner. The presence of lumbar osteoarthritis was evaluated on baseline radiographs using Kellgren and Lawrence (K&L) classification. Grades range from 0 to 4. In our study, osteoarthritis was defined by at least K&L grade 2. This study included 1,254 menopausal women (66.7 ± 7.1 years). Among them, 727 attended the 6-year follow-up visit. Patients with lumbar osteoarthritis had an aBMD higher than those without lumbar osteoarthritis at the lumbar spine, but not at the hip. However, the aBMD significantly increased in all sites with the grade of K&L. In contrast, spine TBS was not different between patients with and without lumbar osteoarthritis (p = 0.70), and it was not correlated with K&L grade. Spine TBS and aBMD at all sites were negatively correlated with age (p < 0.0001). Body mass index was correlated positively with aBMD and negatively with spine TBS (p < 0.0001). The 6-year change of aBMD was significant in the hip and nonsignificant in the lumbar spine. That of TBS was significant, with a 3.3 % decrease (p < 0.0001), independent of K&L grade (p = 0.28). In postmenopausal women, lumbar osteoarthritis leads to an increase in lumbar spine aBMD. In contrast, spine TBS is not affected by lumbar osteoarthritis.Osteoporosis International 04/2014; 25(6). DOI:10.1007/s00198-014-2685-6 · 4.17 Impact Factor
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ABSTRACT: Articular cartilage and subchondral bone are the key tissues in osteoarthritis (OA). The role of the cancellous bone increasingly attracts attention in OA research. Because of its fast adaptation to changes in the loading distribution across joints, its quantification is expected to improve the diagnosis and monitoring of OA. In this study, we simulated OA progression-related changes of trabecular structure in a series of digital bone models and then characterized the potential of texture parameters and bone mineral density (BMD) as surrogate measures to quantify trabecular bone structure. Five texture parameters were studied: entropy, global and local inhomogeneity, anisotropy and variogram slope. Their dependence on OA relevant structural changes was investigated for three spatial resolutions typically used in micro computed tomography (CT; 10 μm), high-resolution peripheral quantitative CT (HR-pQCT) (90 μm) and clinical whole-body CT equipment (250 μm). At all resolutions, OA-related changes in trabecular bone architecture can be quantified using a specific (resolution dependent) combination of three texture parameters. BMD alone is inadequate for this purpose but if available reduces the required texture parameter combination to anisotropy and global inhomogeneity. The results are summarized in a comprehensive analysis guide for the detection of structural changes in OA knees. In conclusion, texture parameters can be used to characterize trabecular bone architecture even at spatial resolutions below the dimensions of a single trabecula and are essential for a detailed classification of relevant OA changes that cannot be achieved with a measurement of BMD alone.12/2014; 3:615. DOI:10.1038/bonekey.2014.110
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ABSTRACT: Variation in the fat mass and obesity-associated (FTO) gene influences susceptibility to obesity. A variant in the FTO gene has been implicated in genetic risk to osteoarthritis (OA). We examined the role of the FTO polymorphism rs8044769 in risk of knee and hip OA in cases and controls incorporating body mass index (BMI) information. 5409 knee OA patients, 4355 hip OA patients and up to 5362 healthy controls from 7 independent cohorts from the UK and Australia were genotyped for rs8044769. The association of the FTO variant with OA was investigated in case/control analyses with and without BMI adjustment and in analyses matched for BMI category. A mendelian randomisation approach was employed using the FTO variant as the instrumental variable to evaluate the role of overweight on OA. In the meta-analysis of all overweight (BMI≥25) samples versus normal-weight controls irrespective of OA status the association of rs8044769 with overweight is highly significant (OR[CIs] for allele G=1.14 [01.08 to 1.19], p=7.5×10(-7)). A significant association with knee OA is present in the analysis without BMI adjustment (OR[CIs]=1.08[1.02 to 1.14], p=0.009) but the signal fully attenuates after BMI adjustment (OR[CIs]=0.99[0.93 to 1.05], p=0.666). We observe no evidence for association in the BMI-matched meta-analyses. Using mendelian randomisation approaches we confirm the causal role of overweight on OA. Our data highlight the contribution of genetic risk to overweight in defining risk to OA but the association is exclusively mediated by the effect on BMI. This is consistent with what is known of the biology of the FTO gene and supports the causative role of high BMI in OA.Annals of the rheumatic diseases 08/2013; 73(12). DOI:10.1136/annrheumdis-2013-203772 · 9.27 Impact Factor