Gender Specific Material Properties in the Thoracic Spine

Gender differences have been identified in a variety of spine-related disorders including rates of thoracic sagittal plane scoliosis and rates of whiplash associated disorder following automotive rear impacts. For example, female gender was identified as a main risk factor for thoracic curve progression in adolescent idiopathic scoliosis [1]. Clinical and epidemiological studies have identified females to be more susceptible to whiplash injury [2]. However, biomechanical evidence for these discrepancies has been limited. Experimental investigations using human volunteers and post mortem human head-neck specimens have identified dynamic gender differences in overall head kinematics relative to T1 [3] and segmental and localized spinal kinematics [4, 5] following simulated automotive rear impacts. However, it remains unclear whether dynamic gender differences resulted from anthropometry, or geometrical or structural differences in the head-neck complex and/or cervical spine. Structural gender differences identified in anterior cruciate ligaments of the knee [6] and histological differences identified in the ligamentum flavum of the lumbar spine may indicate possible structural or material gender differences in spinal ligaments [7]. Therefore, the present investigation was conducted to experimentally identify soft tissue structural differences in spinal biomechanics.