Mechanical Disorders

Degenerative Disc Disease
Facet Arthropathy
Failed Back Syndrome (FBS)
Herniated Discs
Myelopathy
Spondylolisthesis
Spondylolysis
Stenosis
Strains and Sprains

Human beings walk upright, and not on all fours, and as a result the lower back carries most of the body's weight. Because the stresses involved with twisting, turning, lifting, and bending are concentrated in the lower back, this is the part of the spine that is most likely to be injured and become a source of pain. Many people who suffer from back problems are experiencing mechanical pain, which means that a specific part of their spine, such as an intervertebral disc, a ligament, or a joint, is damaged and is not working correctly. While there are many different disorders that can produce mechanical back pain, the following pages explain some of the more common causes of this type of pain.

Degenerative Disc Disease
Degenerative disc disease (DDD) is part of the natural process of growing older. Unfortunately, as we age, our intervertebral discs lose their flexibility, elasticity, and shock absorbing characteristics. The ligaments that surround the disc called the annulus fibrosis, become brittle and they are more easily torn. At the same time, the soft gel-like center of the disc, called the nucleus pulposus, starts to dry out and shrink. The combination of damage to the intervertebral discs, the development of bone spurs, and a gradual thickening of the ligaments that support the spine can all contribute to degenerative arthritis of the lumbar spine.

Degenerative disc disease is as certain as death and taxes, and to a certain degr]\ However, not everyone who has degenerative changes in their lumbar spine has pain. Many people who have "normal" backs have MRIs that show disc herniations, degenerative changes, and narrowed spinal canals. Every patient is different, and it is important to realize that not everyone develops symptoms as a result of degenerative disc disease.

When degenerative disc disease becomes painful or symptomatic, it can cause several different symptoms, including back pain, leg pain, and weakness that are due to compression of the nerve roots. These symptoms are caused by the fact that worn out discs are a source of pain because they do not function as well as they once did, and as they shrink, the space available for the nerve roots also shrinks. As the discs between the intervertebral bodies start to wear out, the entire lumbar spine becomes less flexible. As a result, people complain of back pain and stiffness, especially towards the end of the day.

Symptoms
The most common symptom of degenerative disc disease is back pain. When DDD causes compression of the nerve roots, the pain often radiates down the legs or into the feet, and may be associated with numbness and tingling. In severe cases of lumbar DDD, where there is evidence of nerve root compression, individuals may experience symptoms of sciatica and back pain, and sometimes even lower extremity weakness.

Diagnosis
The diagnosis of degenerative disc disease begins with a complete physical examination of the body, with special attention paid to the back and lower extremities. Your doctor will examine your back for flexibility, range of motion, and the presence of certain signs that suggest that your nerve roots are being affected by degenerative changes in your back. This often involves testing the strength of your muscles and your reflexes to make sure that they are still working normally. You will often be asked to fill out a diagram that asks you where your symptoms of pain, numbness, tingling and weakness are occurring.

A routine set of x-rays is also usually ordered when a patient with back pain goes to see a doctor. If degenerative disc disease is present, the x-rays will often show a narrowing of the spaces between the vertebral bodies, which indicates that the disc has become very thin or has collapsed. Bone spurs begin to form around the edges of the vertebral bodies and also around the edges of the facet joints in the spine. These bone spurs can be seen on an x-ray, where they are called osteophytes. As the disc collapses and bone spurs form, the space available for the nerve roots starts to shrink. The nerve roots exit the spinal canal through a bony tunnel called the neuroforamen, and it is at this point that the nerve roots are especially vulnerable to compression.

In many situations, doctors will order a MRI or a CT scan (CAT scan) in order to evaluate the degenerative changes in the lumbar spine more completely. A MRI scan is very useful for determining where disc herniations have occurred and where the nerve roots are being compressed. A CT scan is often used to evaluate the bony anatomy in the spine, which can show how much space is available for the nerve roots and within the neuroforamen and spinal canal.

Treatment
Your doctor will be able to discuss with you what your diagnosis means in terms of treatment options. For most people who do not have evidence of nerve root compression with muscle weakness, the first line of therapy includes non-steroidal anti-inflammatory drugs and physical therapy. A soft lumbar corset is often prescribed in order to allow the back to have a chance to rest. Surgery is offered only after physical therapy, rest, and medications have failed to adequately relieve the symptoms of pain, numbness and weakness over a significant period of time.

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Facet Arthropathy
The facet joints connect the posterior elements of the vertebral bodies to one another. Like the bones that form other joints in the human body, such as the hip, knee, or elbow, the articular surfaces of the facet joints are covered by a layer of smooth cartilage, surrounded by a strong capsule of ligaments, and lubricated by synovial fluid. Just like the hip and the knee, the facet joints can also become arthritic and painful, and they can be a source of back pain. The pain and discomfort that is caused by degeneration and arthritis of this part of the spine is called facet arthropathy, which simply means a disease or abnormality of the facet joints.

Symptoms
Most people who have facet arthropathy will complain of low back pain that is worse with twisting or extension (bending backwards) of the lumbar spine. The pain is often quite well localized, and unlike the pain and numbness caused by a herniated disc or sciatica, it does not usually radiate into the buttocks or down the legs. However, as the facet joints become arthritic, they often develop bone spurs that can decrease the amount of space available for the nerve roots as they exit the spinal canal. This can be a contributing factor in the development of spinal stenosis, which does cause pain, numbness, and weakness in the buttocks and legs.

Diagnosis
Facet arthropathy is rarely the only cause of significant back low back pain, and patients who have this condition often have other disorders that may be contributing to their symptoms, including degenerative disc disease, arthritis of other parts of the spine, and often spinal stenosis as well. Most people with even mild to moderate amounts of arthritis of the lumbar spine will have evidence of facet joint degeneration on a CT scan (CAT scan) or MRI. A bone scan, which shows areas of active inflammation in the spine, is a test that can be used to determine whether or not facet arthropathy may be contributing to a patient's back pain. The facet joints themselves can be selectively injected with a mixture of a local anesthetic and an anti-inflammatory steroid. If this injection relieves a significant amount of the patient's back pain, and there is evidence to suggest that the facet joints are arthritic (such as a positive bone scan, CT, or MRI), then the diagnosis of facet arthropathy can be made with some confidence.

Treatment
There are several options for treating the pain and symptoms caused by facet arthropathy. The initial treatment of facet joint disease involves avoiding the motions that cause the joints to be painful (such as repetitive twisting, lifting, or extension of the lumbar spine), a course of anti-inflammatory medications, and stretching and strengthening exercises to improve the strength and endurance of the muscles in the lumbar spine. Injections can be used to relieve some of the pain and discomfort of facet arthropathy by quieting down the inflammation and synovitis that is caused by this type of arthritis. Unfortunately, this is often not a permanent solution, and the pain may recur after several months. There are a few techniques that have recently been developed that attempt to alleviate the pain of facet arthropathy by permanently destroying the nerves that innervate the facet joints and "feel" the pain of the arthritis. These procedures use small electrical probes that are inserted through the skin into the area of the nerves to the facet joints, and an electrical current that destroys the nerve is sent to the tip of the probe. This procedure is called a sinu-vertebral nerve ablation.

In other situations, surgery may be indicated to relieve the pain of facet arthropathy. This usually occurs when there is evidence of nerve root compression from enlargement of the facet joints, or other disorders in the lumbar spine (such as degenerative disc disease, spinal instability, or spinal stenosis) that need to be treated with surgery. In the course of most forms of a spinal fusion, the surgeon removes the facet joints between the levels of the spine that are to be fused together, which effectively eliminates the facet joints as a source of future symptoms.

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Failed Back Syndrome (FBS)
Failed back syndrome (FBS) can be described as chronic, severe back and/or leg pain that occurs after back surgery. Multiple factors can contribute to FBS, which can be extremely troubling and disabling:

• The original disease has reoccurred or was not treated completely.* Examples include recurrent disc herniation and ongoing pressure on a nerve.
  
• Complications may arise from back surgery or the natural healing process that follows back surgery.* A joint may become irritated because surgery altered the person's posture and way of moving. Scarring from surgery may cause nerves to become overactive and generate pain.
  
• Other condition(s) may mediate ongoing complaint of back pain.* Conditions such as depression, anxiety, sleeplessness, and/or deconditioning may be present and need to be treated when possible.
  

Neurostimulation or intrathecal drug delivery may be considered whe other conservative treatments, such as exercise or other manual techniques, have failed and when further corrective surgery is not indicated.

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Herniated Discs
Herniated Discs - Herniation describes an abnormality of the intervertebral disc that is also known as a "slipped," "ruptured," or "torn" disc. This process occurs when the inner core (nucleus pulposus) of the intervertebral disc bulges out through the outer layer of ligaments that surround the disc (annulus fibrosis). This tear in the annulus fibrosis causes pain in the back at the point of herniation. If the protruding disc presses on a spinal nerve, the pain may spread to the area of the body that is served by that nerve. Between each vertebra in the spine are a pair of spinal nerves, which branch off from the spinal cord to a specific area in the body. Any part of the skin that can experience hot and cold, pain or touch refers that sensation to the brain through one of these nerves. In turn, pressure on a spinal nerve from a herniated disc will cause pain in the part of the body that is served by that nerve.

Four Degrees of Disc Herniation:

Nuclear Herniation------- Disc Protrusion------Nuclear Extrusion
Sequestered Nucleus

Most disc ruptures will occur when a person is in their thirties or forties when the nucleus pulposus is still a gelatin-like substance. Oddly enough, most disc herniations will occur in the morning. The causes of this phenomenon are not entirely known, but are probably due to the physiology of the spine and the changes in the water content of the disc that occur throughout the day. The two most common locations for a herniated disc in the lower back are at the disc between fourth and fifth lumbar vertebra (L4-5) and at disc between the fifth lumbar vertebra and the first sacral vertebra (L5-S1). These two discs account for 98 percent of all painful disc herniations. A disc herniation can occur elsewhere along the spine, but low lumbar herniations are by far the most common.

Symptoms
Usually a patient's main complaint is a sharp, cutting pain. In some cases there may be a previous history of episodes of localized low back pain, which is present in the back and continues down the leg that is served by the affected nerve. This pain is usually described as a deep and sharp pain, which gets worse as it moves down the affected leg. The onset of pain with a herniated disc may occur out of the blue or it may be announced by a tearing or snapping sensation in the spine that is thought to be the result of a sudden tear of part of the annulus fibrosis.

Diagnosis
A patient with a herniated disc will usually complain of low back pain that may or may not radiate into different parts of the body. They will often demonstrate a limitation in range of motion when asked to bend forward or lean backwards,and they may lean to one side as they try to bend forward. Patients will sometimes walk with an "antalgic" or painful gait, flexing the affected leg so as not to put too much weight on the side of the body that hurts. Straight leg raising may be positive indicating tension on the nerve root.

Abnormalities in the strength and sensation of particular parts of the body that are found with a neurological examination performed by a doctor provide the most objective evidence of nerve root compression. There are no laboratory tests that can detect the presence or absence of a herniated disc, but they may be helpful in the diagnosis of unusual causes of nerve root pain and irritation. An EMG or electromyographic test may help to determine which nerve root in particular is being pinched or is not working normally in the situation where several nerve roots may be involved. An MRI is the test of choice for diagnosis of a herniated disc, but a CT scan (CAT scan) may often be helpful because it provides better visualization of the bony anatomy of the spinal column, indicating where the source of pressure on the nerve root is located.

Treatment
The treatment for vast majority of patients with a herniated disc does not normally include surgery. Eighty percent of patients will respond to conservative therapy when followed for a period of five years. Treatment is most effective when a patient and a doctor have a good relationship and the patient understands the rationale behind the prescribed treatment. The primary element of conservative treatment is controlled physical activity. Usually treatment will begin with very short period of bed rest followed by a gradual return to normal activities. Sitting is bad for this condition because the sitting posture puts a large amount of stress and pressure on the lumbar spine, which may increase the pressure on the affected nerve root. The appropriate use of medications is an important part of conservative treatment. This can include anti-inflammatory drugs, analgesics and muscle relaxants or tranquilizers. Additionally, the right doses of aspirin have been proven to help. Surgical treatment is reserved for patients in whom conservative treatment options are not effective and a sufficient period of time has passed to indicate that the patient may need to have surgery in order to help them to get better.

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Myelopathy
Myelopathy is a term that means that there is something wrong with the spinal cord itself. This disease is very different from the radiculopathy that is caused by isolated points of pressure on individual nerve roots. This process does not commonly occur with low back pain because the spinal cord itself ends at about the level of the first and second lumbar vertebral body. From this point on, only nerve roots occupy the spinal canal. However, in certain situations where there is extensive arthritis and stenosis in the upper parts of the lumbar spine, or elsewhere in the cervical and thoracic spine, a patient may develop myelopathy as a result of compression of the spinal cord. This disease is often first detected as difficulty walking due to generalized weakness or problems with balance and coordination.

Myelopathy is most commonly caused by spinal stenosis, which is a progressive narrowing of the spinal canal. In the later stages of spinal degeneration, bone spurs and arthritic changes make the space available for the spinal cord within the spinal canal much smaller. The bone spurs may begin to press on the spinal cord and the nerve roots, and that pressure starts to interfere with how the nerves function normally.

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Spondylolisthesis
Spondylolysis is a prerequisite to the development of spondylolisthesis. Spondylolisthesis occurs when one vertebra slips forward on the adjacent vertebrae. This will produce both a gradual deformity of the lower spine but also a narrowing of the vertebral canal. It is often associated with pain.

There are five major types of spondylolisthesis:

Type I is called dysplastic spondylolisthesis and is secondary to a congenital defect of either the superior sacral or inferior L5 facets or both with gradual slipping of the L5 vertebra.

Type II, isthmic or spondylolytic, in which the lesion is in the isthmus or pars interarticularis, has the greatest clinical importance in persons under the age of 50. If a defect in the pars interarticularis can be identified but no slipping has occurred, the condition is termed spondylolysis. If one vertebra has slipped forward on the other (horizontal translation), it is referred to as spondylolisthesis.

Type III, is a degenerative spondylolisthesis, and occurs as a result of the degeneration of the lumbar facet joints. The alteration in these joints can allow forward or backward vertebral displacement. This type of spondylolisthesis is most often seen in older patients. In Type III, degenerative spondylolisthesis there is no pars defect and the vertebral slippage is never greater than 30%.

Type IV, traumatic spondylolisthesis, is associated with acute fracture of a posterior element (pedicle, lamina or facets) other than the pars interarticularis.

Type V, pathologic spondylolisthesis, occurs because of a structural weakness of the bone secondary to a disease process such as a tumor or other bone diseases.

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Spondylolysis
Spondylolysis is a defect that occurs in the posterior part of the spine known as the pars intrarticularis. There are many causes of spondylolysis. Spondylolysis usually occurs in young athletes. This disorder is essentially a stress fracture of part of the spine. When occurring at younger ages, it is often a source of lower back pain. Interestingly, this defect will also show up in adults with back pain and no prior history of injury or sports participation. Some adults are found to have a spondylolysis who have no symptoms whatsoever.

Spondylolysis is seldom seen in patients under the age of five and is found in five percent of people over the age of seven. Whether there is a hereditary component of the disease is not clear, but an explanation for the increase in instances relative to age could be explained by the increase in activity of children, as they get older. Young children involved in regular sports are more at risk of developing structural disorders including spondylolysis. Spondylolysis is a common cause of back pain in children, and the most likely cause of pain in patients under age 26, but rarely the only cause of complaints after age 40. *

Spondylolysis becomes a problem if it is painful or associated with instability of the spine. In these situations, it may be associated with lumbar disc degeneration of narrowing of the area where the nerve roots exit the spinal column (the neural foramina). This may be a cause of back and leg pain.

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Stenosis
Lumbar spinal stenosis is a disease that is caused by a gradual narrowing of the spinal canal. This narrowing happens as a result of the degeneration of both the facet joints and the intervertebral discs. In this condition, bone spurs, called osteophytes, which develop because of the excessive load on the intervertebral disc, grow into the spinal canal. The facet joints also enlarge as they become arthritic, which contributes to a decrease in the space available for the nerve roots. The ligaments of the spinal column, especially the ligamentum flavum, become stiff, less flexible, and thicker with age, which also contributes to spinal stenosis. These processes narrow the spinal canal and may begin to impinge and put pressure on the nerves roots and spinal cord, creating the symptoms of spinal stenosis.

Stenosis may occur in the central spinal canal (central stenosis) where the spinal cord or cauda equina are located, in the tract where the nerve root exits the central canal (lateral recess stenosis) or in the lateral foramen (foraminal stenosis) where the individual nerve roots exit out to the body.

Some distortion of the spinal canal will occur in virtually every person as they age, but the severity of the symptoms will depend on the size of a person's spinal canal and the encroachment on the neural elements. The rate of deterioration varies greatly from person to person, and not everyone will feel symptoms.

Spinal stenosis may be caused by a number of processes that decrease the amount of space in the spinal canal available for the neural elements. Degenerative causes are the most common, but there are a few unusual causes of stenosis. These include calcium pyrophosphate crystal deposition, amyloid deposition, and intradural spinal tumors. The reason why stenosis causes weakness and pain is the subject of a significant amount of debate and medical research. Pain in the buttocks or leg, which is a common symptom of lumbar spinal stenosis, may be associated with the compression of the micro-vascular structures carrying blood flow to the nerve roots. At the same time, the symptoms of spinal stenosis may be the direct result of physical compression of the nerve roots. Each of these processes may interfere with the normal function of the nerve roots and decrease the effectiveness and endurance of the spinal nerves.

Symptoms
Some people with degenerative disease of the lumbosacral spine may be totally asymptomatic, some may complain of mild discomfort in the low back, and others may not even be able to walk. In patients who have significant spinal stenosis, they will begin to notice pain in the buttocks, thigh or leg that develops with standing or walking, and improves with rest. In some cases, a patient will complain of leg pain and weakness without having any back pain. More severe symptoms of the disorder include numbness, paresthesias and weakness in the lower extremities. Certain positions can alleviate the symptoms of spinal stenosis by increasing the amount of space available for the nerves. These positions usually involve flexion of the lumbar spine and bending forward. "Any positions that flex the lumbar spine are associated with resolution of symptoms." * For instance, patients with spinal stenosis can ride a bike and walk up an incline or flight of stairs without any pain. They can often walk for extended distances if they have something to lean on, like a shopping cart. However, if they are walking down an incline or flight of stairs, or if they have to give up the shopping cart, their symptoms will often reappear.

The presentation and severity of the symptoms of spinal stenosis depends on the several factors, including the original width of the spinal canal, the susceptibility of the nerves involved, and the unique functional demands of the patient and the pain tolerance of each individual patient.

Diagnosis
The diagnosis of spinal stenosis begins with a complete history and physical examination. The doctor will determine what symptoms are present, what makes them better or worse, and how long they have been present for. A physical examination is essential for determining how severe the condition is, and whether or not it is causing weakness or numbness in certain parts of the body. Abnormalities in the strength and sensation of particular parts of the body that are found with a neurological examination provide the most objective evidence of chronic nerve root compression caused by spinal stenosis. There are no laboratory tests that can detect the presence or absence of a stenosis, but they may be helpful in the diagnosis of unusual causes of nerve root and spinal cord dysfunction. Routine radiographs of the lumbar spine are very helpful in determining the amount of degeneration that is present in the spine, which gives an indirect indication of whether or not spinal stenosis is present. These x-rays are also used to determine if certain parts of the spine are unstable, which may be contributing to the symptoms of stenosis.

A CT scan (CAT scan) provides excellent visualization of the bony anatomy of the spinal column and is an indispensable tool for determining where the stenosis is located. This test is often performed in conjunction with a myelogram, which involves injecting dye into the space occupied by the spinal cord and nerve roots, in order to determine how well the cerebrospinal fluid is able to travel along the nerve roots. An EMG or electromyographic test may help to determine which nerve root in particular is not working normally in the situation where several nerve roots may be involved.

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Strains and Sprains
A back that becomes painful after a hard day at work, a sudden movement, or an injury, has often sustained a strain or sprain of the muscles and ligaments of the back. Most of the stress associated with bending, twisting, and lifting heavy objects is concentrated at the bottom of the spinal column, and this part of the back is particularly susceptible to injury, especially in individuals with weak muscles because they lead a sedentary lifestyle.

A back strain usually occurs when the muscles surrounding the spine are asked to stretch too far, lift too much weight, or move in such a way that they sustain very small tears. As a result of the tearing of the muscles and ligaments, there is usually a microscopic amount of bleeding into the muscle, which results in swelling and painful muscle spasms. Often the muscles that are injured will be tender to the touch. Pain and spasms are the body's way of telling you that a muscle has been injured and needs to be protected from further use. As a result, you should avoid using the injured muscles during this phase of acute pain, and help them to recover by resting, applying hot or cold packs, and possibly obtaining a gentle massage to help ease the spasms.

The actual damage that is done when someone suffers a strained back can be quite variable. The muscles that support and move the spinal column may be injured, the ligaments that connect the vertebral bodies together or form strong capsules around the facet joints might be partially torn, or a mild case of a slipped intervertebral disc may the source of the pain. In each of these situations, the human body is usually able to heal itself, and will do so without surgery if given the proper treatment.

Back strains and muscle spasms are very common and unfortunately, there is not an immediate cure for this type of an injury. However, most back strains can be effectively managed with a course of anti-inflammatory medications, a brief period of rest, and then a gradual return to normal activities. A physical therapy program that includes stretching and strengthening exercises can often help people heal more quickly and is also used to educate them about ways to avoid injuries in the future. Most of these treatments are directed towards reducing the muscle spasms and pain, so that patient is able to take part in their normal daily activities with a minimal amount of discomfort.

If you have a mild amount of pain in your back and you feel like you may have suffered a sprain or a strain, the section on the non-operative treatment of low back pain will be able to provide you with more information about what you can do to help your back to heal. However, you should be aware of a few warning signs that indicate that you should see a doctor about your back pain. These include:

• Changes in the way your bowel and bladder work, causing incontinence or difficulty controlling your bowel movements.
  
• Weakness in the muscles of your legs, a feeling of instability when you walk, or a progressive decrease in the distance that you can walk.
  
• Pain and numbness that travels down your legs, especially when it is worse with sneezing, coughing, or sitting down.
  
• Pain that awakens you at night, or is worse when lying down.
  
• Pain that is associated with fevers, weight loss, or any other signs that suggest that your whole body is not feeling
  

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