Correlation between a Bone Resorption Marker and Structural Geometry of the Proximal Femur in Osteoporotic Women Treated with Raloxifene

Purpose. To assess correlations between a bone resorption marker and the structural geometry of the proximal femur in raloxifene-treated postmenopausal women with osteoporosis. Methods. 45 postmenopausal, osteoporotic women aged 57 to 79 (mean, 67) years underwent raloxifene treatment (60 mg/day) for 12 months. Serum type-I collagen crosslinked N-telopeptide (sNTX) as the bone resorption marker was measured at baseline and 6 months, whereas hip structure analysis (HSA) parameters of the femur (neck, intertrochanter, and shaft) were measured at baseline and 12 months using dual energy X-ray absorptiometry. The HSA parameters included areal bone mineral density (BMD), inner diameter, mean cortical thickness, cross-sectional area, section modulus, and buckling ratio. Correlations between sNTX and HSA parameters were analysed using Pearson's R. Results. At baseline, sNTX correlated inversely with BMD, cross-sectional area, mean cortical thickness, and section modulus, and positively with buckling ratio in the intertrochanter and shaft (but not the neck). These correlations were significant both crude and adjusted for age. After 12 months of raloxifene treatment, HSA parameters improved significantly for the intertrochanter and shaft only. Of the 3 femoral sites, only the change in sNTX at month 6 correlated positively with changes in the inner diameter at the intertrochanter at month 12 ( r=0.303, p=0.045 adjusted for age). Changes in sNTX did not correlate with changes in any other parameters. Conclusion. The surrogate markers for hip fracture including sNTX, BMD, and HSA parameters correlated significantly with each other. Improvement (decrease) of sNTX indicated reduction in bone resorption.