Sex, Age and Stature Affects Neck Biomechanical Responses in Frontal and Rear Impacts Assessed Using Finite Element...

Area of Science:

• Biomechanics
• Orthopedics
• Gerontology

Background:

• Epidemiological data indicate increased injury incidence in the elderly and females compared to males.
• Biomechanical responses to impact, influenced by age and sex-specific neck geometry, are not fully understood.
• Variations in cervical lordosis and facet joint angles contribute to differing injury risks.

Purpose of the Study:

• To develop and validate aged and sex-specific finite element neck models.
• To investigate the biomechanical response of these models to frontal and rear impacts.
• To compare kinematic and strain responses between young/aged and male/female neck models.

Main Methods:

• A novel methodology coupling CAD and repositioning software was used to create aged neck models (F0575YO, M5075YO) from young models (F0526YO, M5026YO).
• Aged models incorporated increased cervical lordosis and facet joint angles.
• Simulations of frontal (2-15 g) and rear (3-10 g) impacts were performed, analyzing head/facet joint kinematics and intervertebral disc shear strain.

Main Results:

• Aged models generally predicted higher tissue deformations, though head kinematics remained similar across all models.
• The M5075YO model uniquely predicted hard tissue failure in frontal impacts due to anterior head position and longer neck.
• The F0575YO model showed higher facet joint shear and rotation, and disc strain in rear impacts compared to F0526YO and M5075YO, attributed to greater lordosis and facet angles.

Conclusions:

• Age and sex-related changes in neck geometry significantly influence biomechanical responses to impact at the tissue level, despite similar head kinematics.
• Increased lordosis and facet angles in aged and female models correlate with higher predicted tissue deformation and strain.
• Findings align with epidemiological data showing increased injury risk with age and in females during rear impacts, particularly Whiplash Associated Disorders.