The Correlation of Bone Mineral Densities among the Lumbar Spines, Proximal Femur and Distal Forearm

Abstract

Purpose:  To determine the correlation of bone mineral density (BMD) among the lumbar spines, proximal femur, and distal forearm in women.

Design: Retrospective, descriptive study

Materials: and Methods:  We reviewed the results of bone mineral density performed at Srinagarind Hospital from May 1997 to June 1999.  Dual energy X-ray absorptiometry (DEXA) technique was used to determine the bone mineral densities (BMDs) at the lumbar spines, proximal femur, and distal forearm in 230 women of age range from 31 to 87 years (mean age = 53.5 years).  Most cases were healthy, with only 10 cases being osteoporotic.

Results: A significant correlation (p<0.001) was found among the three parts of the skeleton examined.  The correlation coefficient (r) was approximately 0.7 between the lumbar spines (average BMD of L2 to L4) and various parts of the proximal femur, was 0.6 between the lumbar spines and various parts of the distal forearm, and was 0.5-0.6 between various parts of the proximal femur and various parts of the distal forearm.

We subdivided the data into two groups, Group 1 with 88 cases aged < 50 years, this group represented pre-menopausal group.  Group 2 with 142 cases older than 50 years of age, this group represented postmenopausal group.

The correlation coefficient at p<0.001, in Group 1 was approximately 0.6 between the lumbar spines (average BMD of L2 to L4) and various parts of the proximal femur, was 0.5 between the lumbar spines and various parts of the distal forearm, and was 0.4-0.6 between various parts of the proximal femur and various parts of the distal forearm.

The correlation coefficient at p<0.001 in Group 2 was approximately 0.7 between the lumbar spines (average BMD of L2 to L4) and various parts of the proximal femur, was 0.5-0.6 between the lumbar spines and various parts of the distal forearm, and was 0.5-0.7 between the various parts of the proximal femur and various parts of the distal forearm.

Conclusions: The BMD of all three parts of the skeleton investigated had significant linear correlation with each other, with mild to moderate degree of correlation.  However, the degree of correlation between the lumbar spines and various parts of the proximal femur was higher than that between the distal forearm and the other parts.

Key words: Correlation, BMD, DEXA