The intervertebral disc serves to bear the load between the vertebral bodies. The nucleus pulposus is the centrally located structure with high water content. The annulus fibrosus is the outer layer of the disc, which is tough and withstands most of the tensile, torsional, and radial stress across the intervertebral bodies. Degenerative process will lead to decrease in water content and decrease in disc space. The collagen content at the annulus changes, with fissuring and radial tear, and causes the disc to budge out. Extrusion of the disc material may occur at the annulus defect. With these pathological changes, the disc can become painful. Degenerative disc disease is common. In a research from the Department of Orthopaedics and Traumatology of the University of Hong Kong, a populational MRI study showed 43% of people under age of 30, and 88% of people older than 50 has lumbar disc degeneration. The various features of degenerative disc can be demonstrated by radiological and MRI imaging, but it has to correlate with the physical symptoms. Some patients with abnormal MRI signal can be completely asymptomatic.
Treatment of Degenerative Disc Disease
Conservative treatment with physiotherapy should be tried, aiming for improvement in function in the presence of the degenerated disc. When conservative treatment failed, a radiologically deceased disc with concordance painful symptoms could be considered for surgery to remove the painful pathology and to regain the stability over the spine. A fusion surgery through various techniques could achieve this purpose, with satisfactory results. Recently, motion preserving surgical option, e.g. artificial disc replacement, has been widely discussed, and the result can be equally successful in a selected group of patient.