Force attenuation properties of various trochanteric padding materials under typical falling conditions of the elderly

Abstract

The purpose of this study was to determine and compare the force attenuation properties of various external trochanteric padding materials under in vitro conditions simulating characteristic falling of the elderly. The selected materials had to be practically suitable for external hip padding so that the main criteria for the materials were good energy absorbing capacity, good durability, low weight, good recovery after compression, easy availability, and reasonable price. Eight materials met these requirements. The first six were flexible cross-linked polyethylene foams with densities from 30 to 200 kg/m3. The seventh material was Plastazote polyethylene foam, and the eight foam was made of ethylene-vinyl acetate (EVA) copolymer. With a pendulum effective mass of 39 kg, impact velocity of 3.0 m/s, and impact force of 8.2 kN, the force attenuation provided by the 20 mm thick hip-padding materials was quite small, ranging from 22 to 38%. With all these materials the peak femoral force remained above 5 kN, more than two times above the femoral fracture threshold (2 kN). In the second set of experiments, the impact force was gradually reduced until the tested materials lowered the impact force below the fracture threshold. With the most efficient material this critical falling velocity was found to be 1.6 m/s. To go below the fracture threshold with the realistic impact velocity of 3.0 m/s, the padding materials had to be 100-140 mm thick.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of pad geometry and material properties on the biomechanical effectiveness of 26 commercially available hip protectors

“…Increasing the thickness of protective devices has previously been shown to increase force attenuation during sideways falls on the hip (Laing et al, 2006;Nabhani and Bamford, 2004;Parkkari et al, 1994;Robinovitch et al, 1995), likely due to decreased stiffness and increased energy absorption. The observed effect of anterior-posterior pad width on force attenuation is also logical, as a wider pad allows energy to be shunted further from the proximal femur.…”

The Association of Hip Circumference With Incident Hip Fracture in a Cohort of Postmenopausal Women: The Iowa Women's Health Study

“…Lower body mass, specifically around the hip region, may offer cushioning and consequent protection from fractures upon falling16-18. Compared to larger hips, small hips may not offer this protection from fractures.…”

Contribution of Trochanteric Soft Tissues to Fall Force Estimates, the Factor of Risk, and Prediction of Hip Fracture Risk*

“…Further support for a key role of trochanteric tissues in hip fracture is provided by studies of external trochanteric padding systems. Laboratory studies indicate that trochanteric padding markedly reduces the loads applied to the hip during a sideways fall (9–11) . Initial randomized controlled studies of hip protectors showed significant prevention of hip fracture (12,13) .…”

“…Laboratory studies indicate that trochanteric padding markedly reduces the loads applied to the hip during a sideways fall. (9)(10)(11) Initial randomized controlled studies of hip protectors showed significant prevention of hip fracture. (12,13) Subsequent studies with different randomization schemes have not confirmed the efficacy of hip protectors.…”