Anatomical hip model for the mechanical testing of hip protectors.

An anatomical hip model has been developed to simulate the impact load on the hip of a falling person wearing a hip protector. The hip consists of an artificial pelvis made of aluminium, linked by a ball-and-socket joint to an anatomically shaped steel femur (thigh bone). The femur is embedded in silicone material with a hip-shaped surface to allow realistic positioning of the protectors with accessory underwear. Additionally, the silicone simulates the damping and load-dispersal effect of soft tissue. A triaxial load sensor is integrated in the neck of the femur to measure the axial and cross-sectional force components in response to external impact forces on the hip. The performance of the hip model was investigated in drop tests and validated against biomechanical data. In a first series of measurements, the shock absorption of 10 different hip protectors, including both energy-absorbing and energy-shunting systems, was analysed. To determine the importance of hip protector placement, each protector was tested in the correct anatomical alignment over the hip and anteriorly displaced by 3 cm. Considerable differences were found between individual hip protectors in their effectiveness to reduce impact forces on the femur. Position of the hip protector also influenced the forces applied to the femur.