IMPACT EXPERIMENTS OF AN EXTERNAL HIP PROTECTOR IN YOUNG VOLUNTEERS

This study represents the first measures and experiences of using an e xternal hip protector in humans under forces that could, without the p rotector, fracture the proximal femur of some of the elderly persons. In other words, we wanted to know if it is possible, using the hip pro tector, to hit the proximal femur of young volunteers with forces Chat have the power to fracture some individuals' proximal femur, and if s o, how intense is the pain reaction under the impacted area? Four of t he researchers (JP, AH, HS, and PK) volunteered to be the study subjec ts. In the impact experiments, we wore the protector on both sides of the pelvis (greater trochanter), and the pendulum, with an effective m ass of 40 kg, was impacted on the protector. The descent height was gr adually increased and the highest impact energy used was 115 J. With a load cell mounted on the head of the pendulum we ensured that the ext ernal forces used were high enough to fracture the proximal femur of s ome of the elderly people. Using the external hip protector we tolerat ed the impacts well although after the high energy impacts every subje ct reported mild tenderness on the skin area under the contact surface of the protector. Repeated examinations of the impacted area of the s tudy subjects did not reveal hematoma or swelling. In conclusion, our test results suggested that, when wearing an anatomically designed ene rgy-shunting and energy-absorbing hip protector, the fall-induced peak impact forces do not cause undue pain to the impacted hip region, and , in all probability, the forces entering into the proximal femur rema in below the range of force capable of fracturing the proximal femur o f the elderly. The protector was found to be comfortable to wear and i t did not move (slip away) during the experiment. We feel that our pro tector is now ready for a feasibility study and then for a randomized clinical trial.