PREDICTION OF HUMAN FEMORAL BONE STRENGTH USING ULTRASOUND VELOCITY AND BMD - AN IN-VITRO STUDY

The stiffness and strength of cancellous bone are important in the man agement of skeletal diseases such as osteoporosis, These properties ar e a function not only of bone density but also of bone architecture, s ome measure of which can be provided by quantitative ultrasound, The a bility of quantitative ultrasound and bone mineral density (BMD) to pr edict stiffness and strength of human femoral heads removed from live subjects during hip replacement was assessed. Stiffness and strength w ere measured using a uniaxial compression test. Ultrasound velocity wa s measured using the pulse-submersion technique (McCue CUBAResearch) a nd BMD using DXA (Lunar DPX-L). Ultrasound velocity (quantitative ultr asound) and stiffness varied with the three orthogonal directions, the highest significance being between the proximo-distal (PD) and antero -posterior (AP) directions (p < 0.0001 for stiffness and p = 0.0003 fo r velocity). Ultrasound velocity was significantly correlated with com pressive bone strength (r = 0.76, p < 0.0001) and stiffness (r = 0.79- 0.83, p < 0.0001). BMD was also significantly correlated with compress ive strength (r = 0.82, p < 0.0001) and stiffness (r = 0.66-0.81, p < 0.001). Using multiple regression analysis both BMD and velocity were significant predictors of strength (r 0.88, p = 0.0004 and 0.0054 resp ectively) and stiffness (r = 0.92, p = 0.0001 and 0.0003 respectively) , BMD and velocity were still independent significant predictors of bo th stiffness (r = 0.93, p < 0.0001 and 0.0001 respectively) and streng th (r = 0.89, p < 0.0001 and 0.02) when they were combined as a produc t (BMDIIV-m), This suggests that BMD measured using DXA, if used in c onjunction with ultrasound velocity, may be able to improve osteoporos is risk assessment. The information about femur anisotropy may also be important for hip prosthesis and in vivo modelling.