Relationship Between Lumbar Spine Hounsfield Unit Values and Bone Mineral Density in Patients With Osteoarthritis...

Hip osteoarthritis (OA) and osteoporosis often coexist, complicating bone mineral density (BMD) assessment because of degenerative changes. We aimed to examine the utility of lumbar spine Hounsfield unit (HU) values in patients with hip OA undergoing total hip arthroplasty (THA).

This study included patients with hip OA who underwent primary THA and preoperative BMD measurements with dual-energy X-ray absorptiometry. BMD was measured in the total hip (TH), femoral neck, lumbar spine (L2-L4), and distal radius. HU values at L4 and L5 were evaluated using preoperative computed tomography of the hip joints for 3-dimensional preoperative planning. To assess the effect of arthritis and deformity, we compared the hips of those with and without OA. Correlation coefficients were used to assess the relationship between the HU values and T-scores.

Overall, 218 hips were analyzed. Moderate correlations were found between lumbar HU values and T-scores at all measurement sites, with the strongest correlations between L5 HU values and T-scores of the nonarthritic TH (rho = 0.64, P < .01). Receiver operating characteristic analysis of nonarthritic hips yielded area under the curves of 0.76 for L4 and 0.77 for L5 (optimal cut-off values: 96.6 HU and 92.6 HU, respectively). In osteoarthritic hips, area under the curve values were 0.82 for L4 and 0.83 for L5 (cut-off values: 118.9 HU and 100.8 HU, respectively).

Lumbar HU values moderately correlated with BMD at all measurement sites, especially at the TH. This may serve as a useful screening tool for osteoporosis before THA in patients with hip OA.