The word spondylolisthesis comes from the Greek words spondylos, which means “spine” or “vertebra,” and listhesis, which means “to slip or slide”. Spondylolisthesis is a condition in which one of the bones of the spine (vertebrae) slips out of place onto the vertebra below it (anterior or posterior). This most commonly occurs at the lumbosacral junction with L5 slipping over S1, but it can occur at higher levels as well.
Grading. A commonly adopted method of grading spondylolisthesis is the Meyerding classification. Each grade is determined by the amount of shift between the two vertebrae. The vertebrae are divided into 4 quarters and graded as follows:
• grade I : 0 – 25 %
• grade II : 25 – 50 %
• grade III : 50 – 75 %
• grade IV : 75 – 100 %
• spondyloptosis : > 100 %
Spondylolisthesis has several main causes:
- Congenital (or dysplastic): congenital means “present at birth.” Congenital spondylolisthesis is the result of abnormal bone formation (usually a defect in the articular processes of the vertebra), putting the vertebra at greater risk for slipping. It usually happens in the area where the lumbar spine and the sacrum come together: the L5-S1 area.
- Isthmic: isthmic spondylolisthesis is caused by a defect, or fracture, of the parts interarticularis; a bone connecting the upper and lower facet joints. The fractures are called spondylolysis; if the vertebra slips forward because it’s not being held in place properly, it’s called spondylolisthesis. Gymnasts, weight lifters, and football linemen are especially prone to this kind of spondylolisthesis. Most common in younger people and tends to affect the L5-S1 vertebral levels.
- Degenerative: with aging, the discs (the cushions between the vertebral bones) lose water, becoming less spongy and less able to resist movement by the vertebrae. The facets can’t control the spine’s movement as well, and they become hypermobile. It usually occurs in older people and most commonly affects the L3-L4 or L4-L5 level.
- Traumatic: traumatic spondylolisthesis is caused by an injury which leads to a spinal fracture or slippage.Similar to the isthmic, the traumatic spondylolisthesis also involves a fracture. However, it’s a fracture of any other part of the vertebra other than the pars interarticularis. The facet joints, for example, can fracture, separating the front part of the vertebra from the back part.
- Pathological: it results when the spine is weakened by disease, such as osteoporosis, an infection or tumor weakening the bones and leading to a fracture that split the vertebra, causing instability and a potential slip.
- Post-surgical (or iatrogenic): it refers to slippage that occurs or becomes worse after spinal surgery. It is caused by a weakening of the pars, often as a result of a laminectomy,
As a quick summary, spondylolisthesis can be caused by:
- a birth defect
- spondylolysis (a defect or fracture in the pars interarticularis)
- degeneration due to age or overuse
Risk factors include a history of repetitive trauma or hyperextension of the lower back or lumbar spine. Athletes such as gymnasts, weight lifters, and football linemen who have large forces applied to the spine during extension are at greater risk for developing isthmic spondylolisthesis.
Patients are often asymptomatic and little or no correlation is found between degree of “slippage” and clinical presentation or pain.
Symptoms and signs may include:
- Lower back pain which may increase with extension.
- Hamstring tightness, hypertonic low back muscles.
- Pain, numbness, or weakness affecting one or both lower extremities only if the slippage causes pressure on the nerves.
- Possible hyperlordosis of lumbar spine.
- Possible pronounced spinous at involved segment, and/or depressed spinous at segments immediately above.
- Weakness in the legs.
- Stiffness of the lower back.
- The neurological exam usually is within normal limits.
X-ray: The lateral view may demonstrate the pars defect, while the oblique projection may show the presence of bilateral pars defects with an appearance resembling a Scottie dog with a collar (the collar is the pars defect.).In addition, plain radiographs also may demonstrate congenital types of spondylolisthesis and the changes of spondylosis. In the setting of trauma, fractures may be apparent. Note that other causes of the patient’s symptoms may be demonstrated, such as an osteoid osteoma, Paget disease, and osteolytic lesions. The grade of spondylolisthesis can be measured by using the lateral view.
Computed tomography (CT): CT scanning of the lumbar spine yields information regarding spondylolisthesis and its cause, along with other possible conditions, such as disk disease, disk herniations, spondylosis, and spinal canal stenosis. Other associations, such as spina bifida, may be seen. In patients with radiculopathy, CT myelography can yield information regarding nerve-root impingement and its etiology, such as disk herniation, abscess, or neoplasm.
Magnetic resonance imaging (MRI): MRI has the distinct advantage of being able to image the spine in any plane without exposure to radiation. Typically, the axial and sagittal planes are used, but images in the coronal plane can also be acquired easily, if needed.
Limitations If present, spondylolisthesis usually is detected on plain radiographs. A spondylolysis may not always be visible. CT scanning is more sensitive for detecting spondylolysis, but occasionally this can be missed, since scanning occurs in the plane of the spondylolysis or from volume averaging. Sagittal reconstruction images are of help in patients with these findings. MRI reveals spondylolisthesis on sagittal views. Spondylolysis may not be readily apparent on MRIs, especially if there is a mild degree of bony sclerosis. Other sclerotic lesions in the pars interarticularis, such as osteoblastic metastases, may give similar appearances.
Treatment for spondylolisthesis depends on several factors, including the age and overall health of the person, the extent of the slip, and the severity of the symptoms. Often is conservative, however more severe spondylolisthesis (grade 3 or grade 4) might require surgery.
Although nonsurgical treatments will not repair the slippage, exercises and appropriate back care (proper lifting, posture, etc.) can help minimize or resolve symptoms.
Rest and medication: The patient should take a break from sports and other activities until the pain subsides. An over-the-counter non-steroidal anti-inflammatory drug (NSAID), such as ibuprofen or naproxen, might be recommended to help reduce pain and inflammation (irritation and swelling). Stronger medications might be prescribed if the NSAIDs do not provide relief. Epidural steroid injections — in which medication is placed directly in the space surrounding the spine — might also help reduce inflammation and ease pain, however it is not recommended to receive these more than three times per year. A brace or back support for a short period of time may be beneficial, however long-term use can lead to atrophy of the paraspinal muscles.
• Osseous mobilization and manipulation may be directed at segment above the slippage to improve biomechanics.
• Electrotherapy modalities: TENS, IFC, US.
• Massage and acupuncture may be beneficial to reduce erector spinae myospasm and low back trigger points.
• A program of exercise and/or physical therapy will help increase pain-free movement, and improve flexibility and muscle strength. Periodic X-rays are done to determine if the bone slippage is continuing.
Exercises: Stabilization exercises are the mainstay of treatment. These exercises strengthen the abdominal and/or back muscles, minimizing bony movement of the spine. Generally, eight to 12 weeks of aggressive daily treatment with stabilization exercises are needed to achieve clinical improvement.
AVOID exercises such as sit-ups, leg lifts/flutter kicks, and running during your recovery. Perform low impact aerobic training to maintain cardiovascular fitness, promote healing, and reduce pain (bike, swim, elliptical trainer, ski machine, etc.). These should be performed with minimal to no pain.
Surgery might be necessary if the vertebra continues to slip or if the pain is not relieved by conservative treatment (at least 3 to 6 months) and begins to interfere with daily activities. The main goals of surgery for spondylolisthesis are to relieve the pain associated with an irritated nerve, to stabilize the spine where the vertebra has slipped out of place, and to increase the person’s ability to function. Usually two surgical procedures are used to treat spondylolisthesis.
1. The first procedure is a decompressive laminectomy, which involves removing the part of the bone that is pressing on the nerves. Decompression is usually performed in patients with radicular leg pain. Although this procedure can reduce pain, removing a piece of bone can leave the spine unstable.
2. The second procedure, called spinal fusion, is performed to provide stability.The most common procedure is a posterolateral fusion which involves putting bone graft material between the transverse processes to encourage a fusion. Fusions are usually augmented with rods and screws to provide stability while the bony fusion becomes solid. The hardware is usually not removed unless complications such as breakage occur. Fusions can also be performed from an anterior approach with removal of the disc and insertion of a cage of some sort augmented with bone or some form of fusion material. Some infusions involve both an anterior and a posterior approach. New minimally invasive surgery (MIS) procedures often involve removal of the disc, insertion of a graft to restore the spinal alignment and insertion of rods and screws to produce stability. These MIS procedures are performed through a series of small incisions with minimal blood loss and very short hospital stays. Success of surgery depends on proper patient selection. Not everyone with a spondylolisthesis improves with surgery.
Most common complication is nerve root impingement/radiculopathy. Lumbar stenosis and cauda equina syndrome may result when a significant slip has occured.
In older patients presenting with radiculopathy and neurogenic intermittent claudication, with or without back pain, a diagnosis of degenerative lumbar spondylolisthesis should be considered.
The spondylolisthesis itself normally does not heal, but exercises and appropriate back care (proper lifting, posture, etc.) can help minimize or resolve symptoms. Occasionally, in cases of severe slippage, surgery to stabilize the segments may be required.
Plain myelography or CT myelography are useful studies to assess spinal stenosis in patients with degenerative lumbar spondylolisthesis. CT is a useful noninvasive study in patients who have a contraindication to MRI, for whom MRI findings are inconclusive or for whom there is a poor correlation between symptoms and MRI findings, and in whom CT myelogram is deemed inappropriate.
Patients with pain, numbness and tingling in the legs may benefit from an epidural steroid (cortisone) injection.
Individuals with spondylolisthesis should exercise caution and avoid contact sports and heavy physical labor if possible (heavy lifting, carrying heavy back packs, using jack hammers, digging work, etc.).