Introduction

Arthritis of the lumbar facet joints can be a source of significant low back pain. Aligned on the back of the spinal column, the facet joints link each vertebra together. Articular cartilage covers the surfaces where these joints meet. Like other joints in the body that are covered with articular cartilage, the lumbar facet joints can be affected by arthritis.

Anatomy

Between the vertebrae of each segment of the spinal column are two facet joints. The facet joints are located on the back of the spinal column. There are two facet joints between each pair of vertebrae, one on each side of the spine. A facet joint is made of small, bony knobs lining up along the back of the spine. Where these knobs meet, they form a joint that connects the two vertebrae. The alignment of the facet joints of the lumbar spine allows freedom of movement as you bend forward and back.

The surfaces of the facet joints are covered by articular cartilage. Articular cartilage is a smooth, rubbery material that covers the ends of most joints. It allows the bone ends to move against each other smoothly, without friction.

Causes

Normally, the facet joints fit together snugly and glide smoothly, without pressure. If pressure builds where the joint meets, the cartilage on the joint surfaces wears off, or erodes.

Each segment in the spine has three main points of movement: the intervertebral disc and the two facet joints. Injury or problems in any one of these structures affects the other two. As a disc thins with aging and from daily wear and tear, the space between two spinal vertebrae shrinks. This causes the facet joints to press together.

Facet joints can also become arthritic due to a back injury earlier in life. Fractures, torn ligaments, and disc problems can all cause abnormal movement and alignment, putting extra stress on the surfaces of the facet joints.

The body responds to this extra pressure by developing bone spurs. As the spurs form around the edges of the facet joints, the joints become enlarged. This is called hypertrophy. Eventually, the joint surfaces become arthritic. When the articular cartilage degenerates, or wears away, the bone underneath is uncovered and rubs against bone. The joint becomes inflamed, swollen, and painful.

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Facet joint arthritis develops slowly over a long period of time. Spinal degeneration in later life is the main cause of facet joint arthritis. Symptoms rarely develop immediately when degeneration is causing the problems. However, rapid movements, heavy twisting, or backward motions in the low back can injure a facet joint, leading to immediate symptoms.

Symptoms

Pain from facet joint arthritis is usually worse after resting or sleeping. Also, bending the trunk sideways or backward usually produces pain on the same side as the arthritic facet joint. For example, if you lie on your stomach on a flat surface and raise your upper body, you hyperextend the spine. This increases pressure on the facet joints and can cause pain if there is facet joint arthritis.

Pain may be felt in the center of the low back and can spread into one or both buttocks. Sometimes the pain spreads into the thighs, but it rarely goes below the knee. Symptoms of nerve compression, numbness or tingling, are usually not felt because facet arthritis generally causes only mechanical pain. Mechanical pain is pain from abnormal movement in the spine.

However, symptoms of nerve compression can sometimes occur at the same time as the facet joint pain. The arthritis can cause bone spurs at the edges of the facet joint. These bone spurs may form in the opening where the nerve root leaves the spinal canal. If the bone spurs rub against the nerve root, the nerve can become inflamed and irritated. This nerve irritation can cause symptoms where the nerve travels. These symptoms may include numbness, tingling, slowed reflexes, and muscle weakness.

Diagnosis

Diagnosis begins with a complete history and physical examination. Your doctor will ask questions about the symptoms and how the problem is affecting your daily activities. Your doctor will then perform a physical examination to determine which back movements cause pain or other symptoms. Skin sensation, muscle strength, and reflexes will also be tested.

X-rays can show if there are problems in the bone tissue in and near the facet joints. The images can show if degeneration has caused the space between the vertebrae to collapse and may show if bone spurs have developed near the facet joints. When more information is needed, your doctor may order an MRI or a CAT scan.

A diagnostic injection may also be used to locate the source of pain. The doctor uses a long needle to inject a local anesthetic (numbing medication) into either the joint or into the nerve that goes to the joint. The doctor watches the needle on a fluoroscope to make sure it reaches the correct spot. A fluoroscope is a special X-ray television that allows the doctor to see your spine and the needle as it moves. Once the doctor is sure the needle is in the right place, the medicine and a special dye are injected. The doctor watches the dye to make sure the medication is correctly placed. The results from the injection help the doctor make the diagnosis. If pain goes away, it helps confirm the source of pain.

Non-surgical Treatment

Facet joint arthritis is mainly treated non-surgically. At first, doctors may prescribe a short period of rest to calm inflammation and pain. Patients may find added relief by curling up to sleep on a firm mattress or by lying back with their knees bent and supported. These positions take pressure off the facet joints.

Your doctor may prescribe anti-inflammatory medication, such as a nonsteroidal anti-inflammatory drug (NSAID) or aspirin. Muscle relaxants are occasionally used to calm muscles that are in spasm. Oral steroid medicine in small dosages may also be prescribed for pain.

Patients often work with a physical therapist. By evaluating a patient's condition, the therapist can assign positions and exercises to ease symptoms. The therapist may recommend traction. Traction is a common treatment for this condition. It gently stretches the low back and takes pressure off the facet joints. The therapist may also prescribe strengthening and aerobic exercises. Strengthening exercises focus on improving the strength and control of the back and abdominal muscles. Aerobic exercises are used to improve heart and lung health and increase endurance in the spinal muscles. Stationary biking offers a good aerobic treatment and keeps the spine bent slightly forward, a position affording relief to many patients with lumbar facet joint arthritis.

Patients who still have pain after trying various treatments may require injections into the facet joint or the small nerves that go to the joint. An anesthetic is used to block pain coming from the facet joint. The procedure to inject the medication into the joint is similar to the diagnostic injection described earlier. A steroid medication is occasionally used instead of the anesthetic. There is no strong evidence that these injections work. However, they seem to have some good short-term results with few side effects, so they shouldn't be abandoned completely. Doctors often have their patients resume physical therapy treatments following an injection.

Surgery

People with facet joint arthritis rarely need surgery. However, facet joint arthritis can be a primary source of chronic low back pain. After trying other types of treatment, some of these patients may eventually require surgery. There are several types of surgery for facet joint arthritis. The two primary operations are facet rhizotomy and posterior lumbar fusion.

Facet Rhizotomy

Rhizotomy describes a surgical procedure in which a nerve is purposely cut or destroyed. Facet rhizotomy involves severing one of the small nerves traveling through the facet joint. The intent of the procedure is to stop the transmission of pain impulses along this nerve. The nerve is identified using a diagnostic injection (described earlier). Then the doctor inserts a large, hollow needle through the tissues in the low back. A special probe is inserted through the needle, and a fluoroscope is used to guide the probe toward the nerve. The probe is slowly heated until the nerve is severed. 

Posterior Lumbar Fusion

Facet joint arthritis mainly causes mechanical pain, the type of pain caused by wear and tear in the parts of the lumbar spine. Fusion surgery for facet joint arthritis is mainly used to stop movement of the painful joints by joining two or more vertebrae into one solid bone. This keeps the bones and painful facet joints from moving.

In this procedure, the surgeon lays small grafts of bone over the back of the spine. Many surgeons will also apply metal plates and screws to prevent the two vertebrae from moving. This protects the graft so it can heal better and faster.

After Surgery

Outpatient physical therapy is usually prescribed only for patients who have extra pain or show significant muscle weakness and deconditioning.

Patients usually don't require physical therapy after facet rhizotomy. Doctors may prescribe a short period of therapy when patients have lost muscle tone in their back and abdominal muscles, when they have problems controlling pain, or when they need guidance about returning to work.

If patients require formal rehabilitation after facet rhizotomy, they will probably only need to attend sessions for two to four weeks. They should expect full recovery to take up to three months.

Patients who've had lumbar fusion surgery normally need to wait at least six weeks before beginning a rehabilitation program. They typically need to attend therapy sessions for six to eight weeks and should expect full recovery to take up to six months.

During therapy after surgery, the therapist may use treatments such as heat or ice, electrical stimulation, massage, and ultrasound to help calm pain and muscle spasm. Then patients begin learning how to move safely with the least strain on the healing back.

As the rehabilitation program evolves, patients do more challenging exercises. The goal is to safely advance strength and function.

As the therapy sessions come to an end, the therapist helps patients get back to the activities they enjoy. Ideally, patients are able to resume normal activities. They may need guidance on which activities are safe or how to change the way they go about their activities.