The Influence of Fall Direction and Hip Protector on Fracture Risk: FE Model Predictions Driven by Experimental Data.

Hip fractures in older adults, which often lead to lasting impairments and an increased risk of mortality, are a major public health concern. Hip fracture risk is multi-factorial, affected by the risk of falling, the load acting on the femur, and the load the femur can withstand. This study investigates the influence of impact direction on hip fracture risk and hip protector efficacy. We simulated falls for 4 subjects, in 7 different impact directions (15° and 30° anterior, lateral, and 15°, 30°, 60°, and 90° posterior) at two different impact velocities (2.1 and 3.1 m/s), all with and without hip protector, using previously validated biofidelic finite element models. We found the highest number of fractures and highest fragility ratios in lateral and 15° posterior impacts. The hip protector attenuated femur forces by 23-49 % for slim subjects under impact directions that resulted in fractures (30° anterior to 30° posterior). The hip protector prevented all fractures (6/6) for 2.1 m/s impacts, but only 10% of fractures for 3.1 m/s impacts. Our results provide evidence that, regarding hip fracture risk, posterior-lateral impacts are as dangerous as lateral impacts, and they support the efficacy of soft-shell hip protectors for anterior- and posterior-lateral impacts.

Galliker ES ，Laing AC ，Ferguson SJ ，Helgason B ，Fleps I ... -  《-》

Comparison of force attenuation properties of four different hip protectors under simulated falling conditions in the elderly: an in vitro biomechanical study.

Kannus P ，Parkkari J ，Poutala J 《-》

Effect of hip protectors, falling angle and body mass index on pressure distribution over the hip during simulated falls.

Choi WJ ，Hoffer JA ，Robinovitch SN 《-》

Effect of soft shell hip protectors on pressure distribution to the hip during sideways falls.

Laing AC ，Robinovitch SN 《OSTEOPOROSIS INTERNATIONAL》

Finite element analysis of hip fracture risk in elderly female: The effects of soft tissue shape, fall direction, and interventions.

This study investigates the effects of fall configurations on hip fracture risk with a focus on pelvic soft tissue shape. This was done by employing a whole-body finite element (FE) model. Soft tissue thickness around the pelvis was measured using a standing CT system, revealing a trend of increased trochanteric soft tissue thickness with higher BMI and younger age. In the lateroposterior region from the greater trochanter, the soft tissues of elderly females were thin with a concave shape. Based on the THUMS 5F model, an elderly female FE model with a low BMI was developed by morphing the soft tissue shape around the pelvis based on the CT data. FE simulation results indicated that the lateroposterior fall led to a higher femoral neck force for the elderly female model compared to the lateral fall. One reason may be related to the thin soft tissue of the pelvis in the lateroposterior region. Additionally, the effectiveness of interventions that can help mitigating hip fractures in lateroposterior falls on the thigh-hip and hip region was assessed using the elderly female model. The attenuation rate of the femoral neck force by the hip protector was close to zero in the thigh-hip fall and high in the hip fall, whereas the attenuation rate of the compliant floor was high in both falls. This study highlights age-related changes in the soft tissue shape of the pelvis in females, particularly in the lateroposterior regions, which may influence force mitigation for the hip joint during lateroposterior falls.

Murakami S ，Zhao Y ，Mizuno K ，Yamada M ，Yokoyama Y ，Yamada Y ，Jinzaki M ... -  《-》