Hip protector case study

About 240,000 hip fractures occur annually worldwide. This chapter discusses a biomedical area where foam products can reduce injuries. It links protector design to the biomechanics of soft tissue deformation and bone fracture. Falls on the hip are not as well understood as head impacts, because few have been reconstructed forensically. A number of test rigs have been designed to rank the products, but there is no general agreement over test methods. This chapter analyzes these test types. If the relative effectiveness of products could be established after several years of use, a product standard could be developed. Fractures tend to occur across the neck of the femoral head. The structure of trabecular bone in the core of the femur is similar to open-cell foams. The spaces are filled with blood cells, marrow, rather than air, but they do not contribute to mechanical strength. The majority of the strength of these long bones comes from the contribution of the compact bone in the outer layers. A low Bone Mineral Density (BMD) is a risk factor for hip fractures; the femoral fracture force increases almost linearly with BMD.