title: The effects of pad geometry and material properties on the biomechanical effectiveness of 26 commercially available hip protectors.
abstract: Wearable hip protectors (padded garments) represent a promising strategy to decrease impact force and hip fracture risk during falls, and a wide range of products are currently marketed. However, little is known about how design features of hip protectors influence biomechanical effectiveness. We used a mechanical test system (simulating sideways falls) to measure the attenuation in femoral neck force provided by 26 commercially available hip protectors at three impact velocities (2, 3, and 4m/s). We also used a materials testing machine to characterize the force-deflection properties of each device. Regression analyses were performed to determine which geometric (e.g., height, width, thickness, volume) and force-deflection properties were associated with force attenuation. At an impact velocity of 3m/s, the force attenuation provided by the various hip protectors ranged between 2.5% and 40%. Hip protectors with lower stiffness (measured at 500N) provided greater force attenuation at all velocities. Protectors that absorbed more energy demonstrated greater force attenuation at the higher impact velocities (3 and 4m/s conditions), while protectors that did not directly contact (but instead bridged) the skin overlying the greater trochanter attenuated more force at velocities of 2 and 3m/s. At these lower velocities, the force attenuation provided by protectors that contacted the skin overlying the greater trochanter increased with increasing pad width, thickness, and energy dissipation. By providing a comparison of the protective value of a large range of existing hip protectors, these results can help to guide consumers and researchers in selecting hip protectors, and in interpreting the results of previous clinical trials. Furthermore, by determining geometric and material parameters that influence biomechanical performance, our results should assist manufacturers in designing devices that offer improved performance and clinical effectiveness.
authors: Injury Biomechanics and Aging Laboratory, Department of Kinesiology, University of Waterloo, 200 University Ave West, Waterloo, Ontario, Canada N2L 3G1. actlaing@uwaterloo.ca
authors: Andrew C
authors: AC
authors: Laing
authors: Fabio
authors: F
authors: Feldman
authors: Mona
authors: M
authors: Jalili
authors: Chun Ming Jimmy
authors: CM
authors: Tsai
authors: Stephen N
authors: SN
authors: Robinovitch
mesh_terms: D000058:Accidental Falls; D006615:Hip; D006801:Humans; D008422:Materials Testing; D011482:Protective Devices; D013314:Stress, Mechanical