Bone mass, bone microstructure and biomechanics in patients with hand osteoarthritis.

BACKGROUND: The impact of primary hand osteoarthritis (HOA) on bone mass, microstructure and biomechanics in the affected skeletal regions is largely unknown. METHODS: HOA patients and healthy controls (HC) underwent high-resolution peripheral quantitative computed tomography (HR-pQCT). We measured total, trabecular and cortical volumetric bone mineral densities (vBMD), microstructural attributes and performed micro-finite element analysis for bone strength. Failure load and scaled multivariate outcome matrices from distal radius and 2nd metacarpal (MCP 2) head measurements were analyzed using multiple linear regression adjusting for age, sex and functional status and reported as adjusted z score differences for total and direct effects. RESULTS: 105 subjects were included (76 HC; 46 women, 30 men/29 HOA; 23 women, 6 men). After adjustment, HOA was associated with significant changes in the multivariate outcome matrix from the MCP 2 head (p < 0.001) explained by an increase in cortical vBMD (∆z = 1.07, p = 0.02) and reduction in the trabecular vBMD (∆z =  - 0.7, p = 0.09). Distal radius analysis did not show an overall effect of HOA however there was a gender-study group interaction (p = 0.044) explained by reduced trabecular vBMD in males (∆z = -1.23, p=0.02). HOA was associated with lower failure load [-514 N (95%CI-1018 to -9), p=0.05] apparent in males after adjustment for functional status. CONCLUSION: HOA is associated with reduced trabecular and increased cortical vBMD in the MCP 2 head and a reduction in radial trabecular vBMD and bone strength in males. Further investigations of gender-specific changes of bone architecture in HOA are warranted.