Assessing the Impact of Rubberized Asphalt on Reducing Hip Fracture Risk in Elderly Populations Using Human Body Models

Abstract

Compared to other age groups, older adults are at more significant risk of hip fracture when they fall. In addition to the higher risk of falls for the elderly, fear of falls can reduce this population’s outdoor activity. Various preventive solutions have been proposed to reduce the risk of hip fractures ranging from wearable hip protectors to indoor flooring systems. A previously developed rubberized asphalt mixture demonstrated the potential to reduce the risk of head injury. In the current study, the capability of the rubberized asphalt sample was evaluated for the risk of hip fracture for an average elderly male and an average elderly female. A previously developed human body model was positioned in a fall configuration that would give the highest impact forces toward regular asphalt. Three different rubber contents with 14, 28, 33 weight percent (% wt.) were implemented as the ground alongside one regular non-rubberized (0%) asphalt mixture, one baseline, and one extra-compliant playground rubber-composite material. The whole-body model was simulated to fall on the rubberized asphalt mixtures with an initial vertical velocity of 3 m/s with a 10° trunk angle and +10° anterior pelvis rotation. The impact forces were measured on the femoral head, and a previously developed hip fracture risk function was used to compare the rubberized asphalt mixtures. It was found that the rubberized asphalt mixture with 33% wt. rubber can reduce the impact forces up to 10% for the elderly male and female model compared to regular asphalt. The impact forces were most reduced for the extra-compliant playground material, with a 23% reduction for the female model. The risk of injury for the asphalt mixture with 33% wt. rubber was reduced up to 18% for elderly females and 20 for elderly males, compared to regular asphalt. The extra-compliant playground material had the most reduction of hip fracture risk for both sexes, 39 and 43% for elderly females and males, respectively.