Degenerative disc disease is a condition where the cushioning intervertebral discs of the spine deteriorate and press upon nerves. This can be associated with damage and wear and tear to the intervertebral disc from aging.
In this disorder, the spinal discs become anatomically altered after losing water content and become thinner. The outer layer of the spinal disc may tear, resulting in expulsion of the contents of the inner core of the disc through the outer covering, a condition known as a herniated disc. These protrusions may press on nerves, causing pain in the back and leg that can range from mild to excruciating.
The medical community has yet to agree on a precise definition for degenerative disc disease, so patients often encounter varying explanations of the disorder. In addition, many consider the “disease” part of the name to be a misnomer. In reality, it is a degenerative condition that sometimes produces pain due to one or more damaged discs.
Although patients with degenerative disc disease will find that their discs continue to degenerate over time, most do not experience a corresponding increase in pain.
Diagnosis typically involves a medical history, physical examination and imaging tests such as x-ray or MRI. Noninvasive treatments such as exercise therapy, medications and rest often help, with spine surgery reserved for hard-to-resolve cases.
About degenerative disc disease
Degenerative disc disease occurs when wear and tear on the intervertebral discs between the bones (vertebrae) in the spinal column cause deterioration that eventually results in pain. This disorder is associated with aging. It is among the most common sources of back pain in people who are middle-aged or older.
As they age, most people suffer some damage to their intervertebral discs, also known as spinal discs. Normally, these discs serve as shock absorbers between the bones of the spine and help the back to stay flexible. The discs are made up of two parts:
Outer layer. This is the tough, fibrous covering (annulus fibrosis) of the disc.
Core. Inside the outer layer is a soft, jelly-like core (nucleus pulposus). It contains about 80 percent water, which gives the core a sponge-like quality, making it better able to absorb spinal stress.
As people age, their spinal discs usually begin to slowly flatten, deteriorate, lose water content, and become thin and more brittle.
The deterioration from this aging process can leave spinal discs vulnerable to the type of injury known as degenerative disc disease. In this disorder, the outer layer of a spinal disc may tear. In some cases, the inner core of the disc may burst through the outer covering in a condition known as a herniated disc. These protrusions sometimes press on nerves, resulting in pain in the back and leg that can range from mild to excruciating.
Patients with degenerative disc disease usually experience several phases of symptoms, which can occur over several decades. Initially, acute back pain may make it difficult to move the back in a normal fashion. Then, the area where the injury occurred becomes inflamed, resulting in back pain that comes and goes over a period of time. Eventually, the body restabilizes the injured part of the back, and the patient usually experiences fewer episodes of back pain because fully degenerated discs have lost the substances (proteins) that caused inflammation and pain.
Degenerative disc disease is a condition that sometimes generates confusion. The medical community has yet to define degenerative disc disease precisely, so patients often encounter varying explanations of the disorder. In addition, many physicians consider the “disease” part of the name to be a misnomer. In reality, it is a degenerative condition that sometimes produces pain due to one or more damaged discs.
Potential causes of degenerative disc disease
To understand how degenerative disc disease unfolds, it is helpful to know more about the anatomy of the spine. Spinal anatomy includes strong bones, flexible ligaments and tendons, large muscles and sensitive nerves. Its most notable feature is the vertebral column, also called the spinal column. It is made up of block-shaped bones called vertebrae that typically total 33 at birth but later become 26 bones because some of the lower vertebrae fuse to become the sacrum and the tailbone (coccyx).
An intervertebral disc (also called spinal disc) separates each of the vertebrae, except the first and second cervical vertebrae. These discs are made up of tough fibrocartilaginous material that is nonetheless elastic. They act as shock absorbers between the vertebrae, shielding the bones from the impact of activities such as jumping from heights or certain forms of exercise. They also add stability to the spine while still allowing for movement between the bones. Each disc is composed of a core of jelly-like material (nucleus pulposus) surrounded by a covering of tough, fibrous material (annulus fibrosis).
Degenerative disc disease is associated with aging. Typically, symptoms related to the disorder first begin to affect people in their 30s or 40s. From the moment a person gets out of bed in the morning, the spine is continuously called upon to support a person’s body weight. Over a period of years, this creates daily stresses and minor injuries that begin to accumulate and wear down the discs of the spine. The role of the discs between the vertebrae is to absorb these stresses so that bones are not injured.
Usually, the first part of the disc to be injured is the outer portion (annulus). Excessive pressure on or injury to the annulus can cause tears. Scar tissue forms in the annulus to repair the tears, but this tissue is not as strong as normal. As more scar tissue forms, the annulus becomes weaker, which can lead to damage of the inner disc (nucleus pulposus). Damage to the nucleus pulposus may result in a loss of water within the disc, which weakens the disc's ability to absorb stress. Damage to the nucleus pulposus can allow the contained proteins to leak out, which inflames nerves and causes pain.
Eventually, wear and tear may accumulate to the point that the discs begin to deteriorate. Over time, spinal discs usually begin to flatten, lose water content, thin out and become more brittle. In addition, injuries and wear and tear suffered during sports or other strenuous activities can sometimes lead to disc damage.
Signs and symptoms of degenerative discs
Pain associated with degenerative disc disease tends to be concentrated in the lower buttocks and upper back. Pain that radiates down into the leg or foot is usually minimal. Depending on the location of the injured disc, neck pain may also occur.
Pain often begins gradually and increases with prolonged sitting or standing. Sitting is particularly likely to aggravate the condition, because it puts three times more load on the intervertebral discs than standing does. On the other hand, patients may find that pain is relieved when they stand upright, move about, walk or lie in the fetal position. Bending, twisting or lifting tends to make the pain worse as it tends to cause more pressure on the discs.
Pain, ranging from mild to severe, can come and go, with episodes lasting from a few days to a few months. Patients who experience weakness in the leg muscles or foot may have suffered damage to a nerve root (radiculopathy).
Diagnosis methods for degenerative discs
Diagnosis of degenerative disc disease typically begins with a medical history. The physician will be particularly interested in the history of a patient’s back pain and may ask questions such as:
When did the back pain begin?
What causes the pain to increase?
Is there a family history of back pain?
The physician will perform a physical examination, paying special attention to the areas where pain occurs. A pain assessment may be conducted.
The physician may also order various imaging tests to better assess the condition of the intervertebral discs. These tests can include:
X-ray. Uses radioactive materials to record images of bone. The physician will look for a decrease in the space between the discs, bone spurs, hardening (sclerosis) of nerve bundles, enlargement (hypertrophy) of the vertebral facets (articulating joints between vertebrae) and instability during flexion (bending) or extension (straightening) of limbs.
The main method of diagnosing a painful degenerative disc is an x-ray procedure called discogram. This is a test in which a physician injects contrast with a small needle into the damaged disc under the guidance of fluoroscopy, which is a real-time x-ray. If the patient is experiencing pain from that damaged disc, then the pressure of the contrast that is injected into the disc will reproduce the patient’s pain. A CAT scan may be done afterward to obtain better anatomical image of the disc.
CAT scan (computed axial tomography). A noninvasive or minimally invasive test that uses multiple computer images, taken from different angles, to create three-dimensional images of body structures. It can be used to identify tumors, herniated discs or other conditions that compress nerve roots. A myelogram (injecting contrast into the spinal canal) can be done prior to the CAT scan to identify precise spinal anatomy and dysfunction.
MRI (magnetic resonance imaging). Uses magnetic waves to create computer-generated images. MRIs can reveal abnormalities with soft tissues, such as nerves or ligaments. They can also help reveal loss of water in a disc, facet joint hypertrophy, narrowing of the spinal canal (stenosis) or a herniated disc.
Treatment options for degenerative discs
Most cases do not require surgery and can instead be treated effectively with nonsurgical techniques, such as:
Physical therapy. Physical therapy has numerous benefits, including helping to improve posture, strengthening the muscles supporting the back and improving flexibility. Stronger spinal muscles may transmit less pressure to the intervertebral discs.
Exercise. Regular physical activity strengthens the muscles of the back, reduces strain on the back by strengthening muscles of the abdomen, arms and legs and reduces the risk of muscle spasms. People who perform weight-bearing exercises can prevent the loss of bone mass due to osteoporosis. This will reduce the risk of compression fractures. Aerobic exercise also promotes the release of endorphins, a natural chemical in the body that combats pain.
Modalities. Physical agents such as those used in thermotherapy, hydrotherapy, cryotherapy or electrical therapy may reduce pain and increase range of motion and function. A physician should be consulted before trying such methods.
Limitation of activity. Certain movements or activities may aggravate pain during acute flare-ups. Activities such as twisting, prolonged sitting and rotating may worsen pain. Some short-term rest may be advisable early. However, patients should not rest for more a few days. Too much rest weakens back muscles and prohibits patients from maintaining the muscle tone they need to recover.
Medication. Over-the-counter anti-inflammatories such as nonsteroidal anti-inflammatory drugs (NSAIDs) can help relieve both inflammation and pain. Medications such as acetaminophen can also help relieve pain but do not reduce inflammation.
In cases of more severe pain, an epidural steroid injection may be performed. This is an injection of corticosteroids, typically given once a month for three months, into the epidural space under x-ray guidance. This treatment is very effective in helping suppress inflammation. The injections are administered into the area around the spinal nerves, providing quick and substantial relief for many patients.
Other medications that may help relieve pain brought on by degenerative disc disease include:
Anticonvulsants. Drugs primarily used to treat seizures. They may also be effective in treating certain types of pain associated with herniated discs. Anticonvulsants are often prescribed with analgesics (pain relievers).
Antidepressants. Some antidepressants can relieve pain and assist with sleep.
Patients should not take any medication without first consulting a physician. Though medications can be effective in relieving pain and reducing inflammation, they cannot stop the degenerative process that occurs with degenerative disc disease.
In some cases, surgery may be necessary to treat degenerative disc disease. Spinal fusion is the most commonly performed surgery for this condition. The procedure permanently connects two or more vertebrae to improve stability, correct a deformity or treat pain. Small pieces of extra bone may be used to fill the space between two vertebrae and fuse the spine. The disc is removed first if the front of the spine is fused.
Spinal fusion eliminates some spinal flexibility, which can be beneficial if movement between spinal segments is the source of a patient’s pain.
Other surgical options may include:
Disc replacement. The U.S. Food and Drug Administration (FDA) has approved an artificial disc to treat degenerative disc disease.
Intradiscal electrothermal therapy (IDET). A wire is inserted into the disc under x-ray and heated to stiffen the disc.
Foraminotomy. The foramen (bony hole) where a pinched nerve root exits the spine is enlarged.
Prevention methods
Exercises may be helpful in preventing pain associated with degenerative disc disease. Stretching and strength training can make back and abdominal muscles stronger to ease pressure on the intervertebral discs, which serve as cushions between the vertebrae. Patients should not undertake any exercise program without first consulting a physician.
Good posture can also relieve pressure on the back. The back supports body weight most efficiently when excess spinal curvature is reduced. When lifting heavy objects, bend at the knees and hips and keep the back straight. Hold objects close to the body while carrying them. Other tips include:
When standing for long periods of time, put one foot on a stool or box to relieve pressure on the back.
When sitting for long periods of time, put feet on a stool so knees are higher than hips and get up and walk around periodically.
Maintain proper body weight. Excessive body weight can increase the load on the lower back, and also increase the risk of a herniated disc.
Do not wear high-heeled shoes.
Do not sleep on the stomach.
Ongoing research
Researchers are studying the potential role of artificial spinal disc replacement surgery as a means of treating degenerative disc disease. In this procedure, the damaged disc is removed and a disc made of metal and plastic that is about the size of a quarter is inserted into the spine. It is believed that ideal candidates for this surgery have the following characteristics:
Between 20 and 60 years old
Have just one degenerating disc
Do not have a systemic bone disease, such as osteoporosis
Have tried other nonsurgical treatments without success
So far, studies indicate that patients who have this surgery recover more quickly and have fewer complications than patients who have more traditional forms of surgery. The U.S. Food and Drug Administration (FDA) has approved an artificial disc to treat degenerative disc disease. Other prostheses are being developed, including some that replace only a disc’s core (nucleus pulposus).
Five years after performing the first transplants of intervertebral discs from humans, Chinese surgeons in 2007 reported long-term success in relieving chronic back pain due to disc degeneration. However, it may take many more years of research before such transplants are approved in the United States.
Other areas of research include tissue engineering and regeneration.
Questions for your doctor
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about degenerative disc disease:
Could my back pain or leg pain be caused by degenerative disc disease?
What diagnostic tests might I need to undergo, and what do they involve? Who will explain my test results to me, and when?
What do my test results indicate?
How is degenerative disc disease causing my pain – do I have a pinched nerve? A herniated disc? Other factors?
Will my pain become worse over time?
What are my treatment options?
How can I tell when to rest and when to be active?
Are there ways I can improve posture and ergonomics to ease my condition?
Will exercise make my pain go away? Do you recommend any particular exercises for me? Are there any activities I should avoid?
What over-the-counter medications can help me? If these don’t work, what prescription drugs might be tried?
Do you recommend methods such as heat therapy, water therapy or cold therapy? If so, what is the best way for me to carry these out at home? Or should I have them as part of physical therapy?
If nonsurgical treatments fail, is surgery an option for me?
