CORRELATION OF BONE MINERAL DENSITY MEASURED BY DXA WITH MATERIAL PROPERTIES OF THE FEMORAL NECK

Abstract

Introduction: Osteoporosis is one of the major diseases worldwide, affecting millions of elderly people, with severe economical and medical consequences. The most commonly used method for the determination of decreased bone quality is the assessment of Bone Mineral Density, measured by dual X-ray absorptiometry (DXA). However DXA is quantitative and not qualitative index of the bone structure.

The purpose of this study was to correlate the bone mineral density measured by DXA with the mechanical properties of the femoral neck.

Materials and Methods: Bone mineral density of the proximal femur of 30 patients (27 women, 3 men) undergoing total hip displacement was estimated by DXA. The average age of these patients was 63.7 years. Patients with sort femoral neck or previous surgeries in proximal femur were excluded from the study. After hip replacement bone samples (femoral head and neck) were frozen and stored at −60 °C.

A plane bone slice with 6mm thickness was sawed of femoral neck using a double cutting saw. The exact specimen dimensions were measured using a sliding calliper with high accuracy.

All bone specimens were destructively tested on a material testing machine, in order to determine the material properties (Young’s modulus and yield stress) of the samples. The maximum available compression load was 100 kN with a load rate of 10 kN/min. The operational parameters and experimental data were fully controlled and handled by a graphical software package. Finally all data were evaluated and statistically analyzed.

Results: A strong linear correlation of bone mineral density (T-score) with maximum failure load of samples was noted (R2=0.852). No significant differences in Young’s modulus values, was found between bone samples.

Conclusions: Bone mineral density measured by DXA, although has limitations, remain a strong predictor of bone strength in the femoral neck region.