2023 年 89 巻 917 号 p. 22-00246
As Japan faces a super-aging society, the increasing number of elderly people who are bedridden due to fall fractures has become a major social issue. Hip protectors have, thus, been proposed to prevent femoral fractures in cases of tumbling or falling; however, they are not widely used because the tightness of the equipment and the hassle of wearing it. In recent years, flooring materials with high buffer performance have been attracting special attention in the prevention of bone fractures in cases of tumbling or falling. So far, however, the “floor hardness test,” which is an evaluation method for cephalopathy (concussion of the brain), is the only risk assessment method for injury risks caused by flooring materials, and no such evaluation method is available for femoral fracture risks. Therefore, we fabricated a test instrument (pendulum tester) that reproduces the load that the femur received at the point of falling on the floor and developed a mechanism to assess fracture risks with high accuracy on the basis of the measured load. The pendulum tester is characterized by the following features: (1) has an impactor simulating the shape of the femoral region (made using the femoral computed tomography image of the elderly as a reference) and (2) has a dummy skin reproducing the buffering performance of human soft tissue. On conducting fracture risk assessment of four types of commercially marketed flooring materials using the pendulum tester, we found that the merits and demerits of the safety vary greatly by comparing with the evaluation results of the floor hardness test. The above-mentioned results show that an appropriate flooring material evaluation method should be chosen depending on the lesion site and type of injury.
