Degenerative Disc Disease
Degeneration of one or more intervertebral disc(s) of the spine, often called “degenerative disc disease” (DDD) or “degenerative disc disorder,” is a pathologic process of uncertain etiology that may cause acute or chronic low back pain. The typical radiographic findings in DDD are disc space narrowing, vacuum disc, end plate sclerosis, and osteophyte formation. DDD can greatly affect the sufferer’s quality of life. Disc degeneration is a disease of aging, and though for most people is not a problem, in certain individuals a degenerated disc can cause severe chronic pain if left untreated.
Signs and symptoms
With symptomatic degenerative disc disease, chronic low back pain sometimes radiates to the hips, or there is pain in the buttocks or thighs while walking; sporadic tingling or weakness through the knees, hands, and fingers may also be evident. Similar pain may be felt or may increase while sitting, bending, lifting, and twisting. Chronic neck pain can also come from the cervical spine, with pain radiating to the head, shoulders, arms and hands.
After an injury, some discs become painful because of inflammation and the pain comes and goes. Some people have nerve endings that penetrate more deeply into the anulus fibrosus (outer layer of the disc) than others, making discs more susceptible to becoming a source of pain. The scientific community has the opinion that the healing process involved in the repair of trauma to the outer anulus fibrosus results in the innervation of the resultant scar tissue, and subsequent pain in the disc, as these nerves become inflamed by nucleus pulposus material. Degenerative disc disease can lead to a chronic debilitating condition and can have a serious negative impact on a person’s quality of life. When pain from degenerative disc disease is severe, traditional nonoperative treatment may be ineffective.
Degenerative discs typically show degenerative fibrocartilage and clusters of chondrocytes, suggestive of repair. Inflammation may or may not be present. Histologic examination of disc fragments resected for presumed DDD is routine to exclude malignancy.
Fibrocartilage replaces the gelatinous mucoid material of the nucleus pulposus as the disc changes with age. There may be splits in the anulus fibrosus, permitting herniation of elements of nucleus pulposus. There may also be shrinkage of the nucleus pulposus that produces prolapse or folding of the anulus fibrosus with secondary osteophyte formation at the margins of the adjacent vertebral body. The pathologic findings in DDD include protrusion, spondylolysis, and/or subluxation of vertebrae (sponylolisthesis) and spinal stenosis.
Often, degenerative disc disease can be successfully treated without surgery. One or a combination of treatments such as physical therapy, chiropractic manipulative therapy (CMT) and other chiropractic treatments, osteopathic manipulation, anti-inflammatory medications such as nonsteroidal anti-inflammatory drugs, traction, or spinal injections often provide adequate relief of troubling symptoms.
Surgery may be recommended if the conservative treatment options do not provide relief within two to three months. If leg or back pain limits normal activity, if there is weakness or numbness in the legs, if it is difficult to walk or stand, or if medication or physical therapy are ineffective, surgery may be necessary, most often spinal fusion. There are many surgical options for the treatment of degenerative disc disease. The most common surgical treatments include:
- Anterior cervical discectomy and fusion: A procedure that reaches the cervical spine (neck) through a small incision in the front of the neck. The intervertebral disc is removed and replaced with a small plug of bone or other graft substitute, and in time, that will fuse the vertebrae.
- Cervical corpectomy: A procedure that removes a portion of the vertebra and adjacent intervertebral discs to allow for decompression of the cervical spinal cord and spinal nerves. A bone graft, and in some cases a metal plate and screws, is used to stabilize the spine.
- Dynamic Stabilisation: Following a discectomy, a stabilisation implant is implanted with a ‘dynamic’ component. This can be with the use of Pedicle screws (such as Dynesys or a flexible rod) or an interspinous spacer with bands (such as a Wallis ligament). These devices off load pressure from the disc by rerouting pressure through the posterior part of the spinal column. Like a fusion, these implants allow maintain mobility to the segment by allowing flexion and extension.
- Foraminotomy: A procedure that enlarges the vertebral foramen to increase the size of the nerve pathway. This surgery can be done alone or with a laminotomy.
- Intervertebral disc annuloplasty (IDET): A procedure wherein the disc is heated to 90 °C for 15 minutes in an effort to seal the disc and perhaps deaden nerves irritated by the degeneration.
- Intervertebral disc arthroplasty: also called Artificial Disc Replacement (ADR), or Total Disc Replacement (TDR), is a type of arthroplasty. It is a surgical procedure in which degenerated intervertebral discs in the spinal column are replaced with artificial ones in the lumbar (lower) or cervical (upper) spine.
- Laminoplasty: A procedure that reaches the cervical spine from the back of the neck. The spinal canal is then reconstructed to make more room for the spinal cord.
- Laminotomy: A procedure that removes only a small portion of the lamina to relieve pressure on the nerve roots.
- Microdiscectomy: A minimally invasive surgical procedure in which a portion of a herniated nucleus pulpolsus is removed by way of a surgical instrument or laser while using an operating microscope or loupe for magnification.
- Percutaneous disc decompression: A procedure that reduces or eliminates a small portion of the bulging disc through a needle inserted into the disc, minimally invasive.
- Spinal decompression: A non-invasive procedure that enlarges the Intra Vertebral Foramen (IVF) by aiding in the rehydration of the spinal discs.
- Spinal laminectomy: A procedure for treating spinal stenosis by relieving pressure on the spinal cord. A part of the lamina is removed or trimmed to widen the spinal canal and create more space for the spinal nerves.
New treatments are emerging that are still in the beginning clinical trial phases. Glucosamine injections may offer pain relief for some without precluding the use of more aggressive treatment options. In the US artificial disc replacement is viewed cautiously as a possible alternative to fusion in carefully selected patients, yet it is widely used in a broader range of cases in Europe, where multi-level disc replacement of the cervical and lumbar spine is common. Adult stem cell therapies for disc regeneration are in their infancy. Investigation into mesenchymal stem cell therapy knife-less fusion of vertebrae in the United States began in 2006.