Determination of Geometric Indices of the Femoral Bone Density and its Association with Bone Density of Proximal Femur

Geometric indices of the femoral neck and bone mineral density (BMD) have been proposed to play a major role in prediction of hip fracture risk, with some studies showing a racial variation in such indices. However, no data study in Iran has estimated these parameters for Iranian patients, nor has the relationship between these indices and BMD parameters in different sub-regions of hip been investigated. Postmenopausal women referred to the bone densitometry center of the Shariati Hospital comprised the study population. Patients with apparent risk factors of osteoporosis were excluded. Bone mass was determined using dual-energy X-ray absorptiometry on Lunar DPX bone densitometers. For calculation of femoral neck geometric indices, the printout of the hip densitometry with magnification of ½ was used. Hip axis length (HAL) and neck-shaft angle (NSA) were the main outcomes of the study. We used Pearson correlation analysis for determination of relationship between geometric indices and other variables and multivariate linear regression analysis for adjustment of other independent variables in prediction of femoral BMD. Among 103 postmenopausal women studied, mean HAL was 99.8±4.3 millimeters and mean NSA was 120.3±4.3 degrees. Pearson correlation analysis revealed no correlation between HAL and NSA with BMD results of different sub-regions of hip, but there was a significant positive correlation between HAL and height and weight neither did multivariate regression analysis reveal any significant relationship between HAL and NSA with BMD of total femur and femoral neck. Conculsion: According to our results, it is unlikely that geometric indices play a major role in determination of hip BMD parameters making their routine use in bone densitometry centers not essential supported. Mean HAL of Iranian women is lower than that of Western countries and higher than that of East Asian countries. This is in line with observation of rates of hip fracture in Iran lower that Western rates and higher than Eastern rates.