Lumbar Spinal Mechanics in Pure Bending: Influence of Gender, Spinal Level, and Degeneration Grade

Gender differences have been identified in normal and traumatic motions of the spine. In the cervical region, spinal motions in females were significantly greater than in males during identical dynamic acceleration pulses [1]. Static cervical range of motion was also shown to be greater in female volunteers [2]. In the thoracic region, gender differences were identified in compressive and tensile elastic moduli [3]. Although male volunteers had slightly greater lumbar spine mobility, the difference was not statistically significant [4]. Another study reported that female lumbar specimens were somewhat more flexible than male specimens [5]. Lumbar spinal motions are clinically important in the diagnosis of abnormalities and instability. Increased motions occur secondary to instability and may indicate a need for spinal stabilization. However, although previous studies have provided baseline data for lumbar motions [6], possible variations in spinal motions between males and females may lead to inaccurate diagnosis. Therefore, the purpose of this investigation was to define lumbar spinal motions on a level-by-level basis to determine statistically significant differences between males and females and at varying levels of degeneration.