Spinal Stabilisation: 2. Limiting Factors to End-range Motion in the Lumbar Spine

Abstract

Biomechanical factors which limit range of motion in the lumbar spine are reviewed. The effects of axial compression on the vertebral body, intervertebral disc, and zygapophyseal joints are considered. During axial compression blood is squeezed from the vertebral body leaving a latent period of reduced shock-absorbing ability. Continuous repeated loading of the spine is therefore not recommended during exercise. Intradiscal pressure varies with different body positions, and is especially high during slumped sitting, making this an inappropriate starting position during exercise. Marked loss of height through discal compression is seen following certain weight training exercises making these unsuitable for subjects with discal pathologies. The shock absorbing properties of the disc reduce with age, an important consideration when prescribing exercise for older people. Flexion and extension movements combine sagittal rotation and translation of the vertebrae, leading to facet impaction at end range. Impaction is more damaging with momentum from fast movements. The importance of relative stiffness and muscle length to lumbar-pelvic rhythm is highlighted. The relevance of articular tropism is examined. The proprioceptive role of the deep intersegmental muscles of the spine is considered, and the importance of proprioceptive training during rehabilitation of spinal dysfunction is emphasised. Biomechanical factors which limit range of motion in the lumbar spine are reviewed. The effects of axial compression on the vertebral body, intervertebral disc, and zygapophyseal joints are considered. During axial compression blood is squeezed from the vertebral body leaving a latent period of reduced shock-absorbing ability. Continuous repeated loading of the spine is therefore not recommended during exercise. Intradiscal pressure varies with different body positions, and is especially high during slumped sitting, making this an inappropriate starting position during exercise. Marked loss of height through discal compression is seen following certain weight training exercises making these unsuitable for subjects with discal pathologies. The shock absorbing properties of the disc reduce with age, an important consideration when prescribing exercise for older people. Flexion and extension movements combine sagittal rotation and translation of the vertebrae, leading to facet impaction at end range. Impaction is more damaging with momentum from fast movements. The importance of relative stiffness and muscle length to lumbar-pelvic rhythm is highlighted. The relevance of articular tropism is examined. The proprioceptive role of the deep intersegmental muscles of the spine is considered, and the importance of proprioceptive training during rehabilitation of spinal dysfunction is emphasised.