The Multi-Modal Risk Analysis and Medical Prevention of Lumbar Degeneration, Fatigue, and Injury Based on FEM/BMD for Elderly Chinese Women Who Act as Stay-Home Grandchildren Sitters

Background: An increasing number of Chinese elderly women stayed home and acted as grandchildren sitters. In consequence of the frequent loading-bear, chronic lumbar fatigue probably caused higher risk of lumbar degeneration, fatigue and injury which has become one of the most important aging and health problems in China. In this study, a multi-mode lumbar finite element model (FEM) with specific bone mineral density (BMD) were developed and validated for further spine injury prevention and control. Methods: The material properties of lumbar vertebra were modified according to degenerated bone mineral density, and geometry was adjusted based on intervertebral disc height. The motion of lifting lift children was simulated by a 76 year-old Chinese women's FEM, and the stress distribution was calculated and predicted. Results: The pressure of L5-S intervertebral disc in the bending 3-year-old dummy lifting posture was significantly higher than the same posture without lifting, the maximum effective stress of endplate cartilage in upright with lifting child posture, was 1.6 times of in the bending without lifting posture. And the fatigue risk limitation frequency of upright with dummy was predicted with the functional equation of fatigue and stress which was deduced by genetic algorithm, which combined with the effective stress of lumbar vertebrae spongy bone calculated from FEM. Conclusions: Lifting child motion could increase the risk of lumbar degeneration, fatigue and injury in elder women, and they should keep below the limit frequency of the motion of lifting lift children in their daily life. This study could put forward a scientific injury prevention guidance to Chinese elderly women who lifting lift children in daily life frequently.