Densitometric studies of the tensile strength of the proximal femur

Abstract

The prognostic assessment of the fracture resistance of the proximal femur is of great importance to the age related increasing incidence of femur neck fractures. This is particularly important in sport for the elderly. The statistical relationship between the osteodensitometrically determined bone density and the risk of a femur neck fracture has been shown in epidemiological studies, whereby the determination of bone density at the proximal femur has provided the most precise predictive results. The present investigation determines the direct relationship between bone density and fracture resistance. Twenty isolated femurs were investigated with the DPX-L-system (Lunar) to measure the bone density in three different areas of the metaphysia as well as important morphometric parameters. Subsequently the femora were fractured in a special device which also recorded the forces required for fracture. The statistical analysis showed a high correlation between the fracture forces and the bone density of the femur neck and trochanter regions. This was true to a lesser extent in the Ward triangle. No significant correlation was found to the morphometric parameters. Quite different forces with considerably greater amplitudes can occur in falls. These may also be absorbed by different structures such as muscle tissue, and, therefore not act directly upon the femur neck. Despite these limitations the determination of bone density appears to permit the individual estimation of fracture risk of the femur neck.