Background/Purpose:

Hip osteoarthritis (OA) is a major public health concern. It is associated with hip pain, functional decline and possibly increased cardiovascular mortality. The determinants of hip OA, however, are not as well understood as those of other OA sites, such as the knee. Therefore, we sought whether hip geometry, bone mineral density and microarchitecture were associated with hip OA.

Methods:

We have studied 1537 post-menopausal women from the QUALYOR prospective cohort. At baseline, we measured areal BMD by DXA at the lumbar spine and the hip, volumetric BMD and geometry by hip quantitative computerized tomography (QCT) scan using the Bone Investigational Toolkit (BIT) software, and microarchitecture at the distal radius and tibia by high resolution peripheral quantitative tomography (HRpQCT).We built a hip OA score (CT OA score) with images from the hip CT, based on the depiction of the four major signs of osteoarthritis: increased density of the subchondral bone, joint space narrowing, osteophytes and subchondral cysts. The severity of each of these four signs was graded as absent, light, moderate or severe (semi-quantitative score ranging from 0 to 3 for each sign thus 0 to 12 in total). Women with and without hip OA were compared by way of analysis of variance and multivariable modeling.

Results:

The mean age was 65.9 and the man body mass index was 24.6. Among these 1537 women, 670 had a OA score of 0, 710 between 1 and 4 (mild OA) and 157 greater than 4 (severe OA). Women with severe osteoarthritis had significantly higher areal BMD at the lumbar spine (0.866 vs 0.875, p <0.05) and the femoral neck (0.656 vs 0.671, p <0.005); significantly higher area (30.74 vs 31.95, p <0.001) and volume (85.58 vs 89.90, p <0.001) of the hip and lower trabecular hip BMD (128.1 vs 123, p<0.001 ). Cortical hip BMD did not differ between women with and without hip OA (964.5 vs 969, p =0.45). The BIT analysis showed higher parameters of bone resistance (CSA with 8.36 vs 8.91, CSMI with 5.68 vs 6.51 and Z polar with 7.66 vs 8.4, p <0.001) at the OA femoral neck, more important trochanter, femoral and global width and hip axis length, and a significantly lower cortical thickness. In multivariable analysis, parameters most strongly related to severe OA were the trabecular and cortical volumes of the femoral neck, in the dominant and non-dominant hip. No difference was observed in peripheral bone microarchitecture between hip OA patients and non OA individuals.

Conclusion:

Women with hip OA have a bigger femoral neck, suggesting a sizeable role of bone geometry in the pathophysiology of hip OA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-of-hip-bone-geometry-and-volumetric-density-with-hip-osteoarthritis/