tailieunhanh - Spinal Disorders: Fundamentals of Diagnosis and Treatment Part 13

Spinal Disorders: Fundamentals of Diagnosis and Treatment Part 13. Spinal disorders are among the most common medical conditions with significant impact on health related quality of life, use of health care resources and socio-economic costs. Spinal surgery is still one of the fastest growing areas in clinical medicine. | Age-Related Changes of the Spine Chapter 4 95 The Intervertebral Disc and Cartilage Endplate The intervertebral discs are located between the vertebral bodies. They transmit load arising from body weight and muscle activity through the spinal column and also provide flexibility to the spine by allowing bending flexion and torsion. The discs of the lumbar spine are approximately 7-10 mm thick and 40 mm in diameter anterior-posterior representing one-third of the height of the spine 120 141 . Generally the discs consist of three highly specialized structures the anulus fibrosus the nucleus pulposus and the cartilage endplate that forms the interface with the adjacent vertebral bodies. The disc consists of three highly specialized structures Intervertebral Disc Among all the tissue components of the spine the intervertebral discs exhibit the most striking alterations with age. Because of these dramatic changes many spine specialists believe that the disc is a major source of back and neck pain. The intervertebral disc has attracted much research to unravel the underlying molecular mechanism of disc degeneration. Although the intervertebral disc is much better explored than other components of the spine our understanding of its molecular biology is still in its infancy. The intervertebral disc undergoes dramatic alterations with aging Normal Anatomy and Biochemical Composition The anulus fibrosus is made up of 15-25 concentric rings consisting of parallel collagen fibers. These rings are termed lamellae and are visible macroscopically in healthy discs. The collagen fibers in each lamella are oriented at approximately 60 to the vertical axis alternating left and right to the adjacent lamellae see Chapter 2 . Elastin fibers intersperse the lamellae and may play an important role in restoration of shape after bending of the spine 161 . The cellular part of the anulus fibrosus consists of thin and elongated fibroblast-like cells aligned to the collagen fibers Fig. 2 114 .