What is Spondylolisthesis?
Spondylolisthesis is a condition in which one of the bones of the spine (vertebrae) slips out of place and onto the vertebra below it. If it slips too much, the bone can press on a nerve causing pain. Usually the bones of the lower back are affected.
The more common types of Spondylolisthesis include:
- Congenital Spondylolisthesis - Present at birth, congenital spondylolisthesis is the result of abnormal bone formation. This abnormal arrangement of the vertebrae puts them at greater risk for slipping.
- Isthmic Spondylolisthesis - Occurs as the result of spondylolysis, a condition that leads to small stress fractures (breaks) in the vertebrae that weaken the bone so much it slips out of place.
- Degenerative Spondylolisthesis - The most common form of the disorder is caused when aging discs (the cushions between the vertebral bones) lose water and become less spongy and flexible.
Less common forms of spondylolisthesis include:
- Traumatic Spondylolisthesis - Caused when an injury leads to a spinal fracture or slippage
- Pathological Spondylolisthesis - Occurs when the spine is weakened by disease such as osteoporosis, infection, or tumor
- Post-surgical Spondylolisthesis - Slippage that occurs or becomes worse after spinal surgery
How Common is Spondylolisthesis?
Spondylolisthesis is the most common cause of back pain in teens, who often begin showing symptoms during the teenage growth spurt. Degenerative spondylolisthesis occurs most often after age 40.
Symptoms of Spondylolisthesis
Oftentimes people with spondylolisthesis are non-symptomatic and don’t even know they have the condition. When symptoms do occur, the most common one is low back pain which often spreads across the lower back and might feel like a muscle strain.
Spondylolisthesis can also cause muscle spasms in the hamstring muscles in the back of the thighs. Tight hamstrings can cause a person to walk with short strides and with the knees slightly bent. If the slipped vertebra is pressing on a nerve, pain might spread down the leg to the foot. The foot might also tingle and/or feel numb.
How is Spondylolisthesis Graded?
A radiologist is able to determine the degree of slippage by viewing the results of specialized X-rays. Slippage is graded I through IV:
- Grade I – 1 percent to 25 percent slippage
- Grade II – 26 percent to 50 percent slippage
- Grade III – 51 percent to 75 percent slippage
- Grade IV – 76 percent to 100 percent slippage
Generally, Grade I and Grade II slippages do not require surgical treatment and are treated medically. Grade III and Grade IV slippage might require surgery in cases where the patient experiences persistent pain or discomfort.
An X-ray of the lower back can show a vertebra out of place; however, the more detailed images of a computed tomography (CT) scan or a magnetic resonance imaging (MRI) scan may be needed to more clearly see the bones and nerves involved.
Treatment for spondylolisthesis depends on several factors, including the age and overall health of the person, the extent of the slippage, and the severity of the symptoms. Treatment is most often conservative (see below). More severe spondylolisthesis may require surgery.
- Conservative treatment - This involves rest, medication and moderate exercise. Taking a break from sports and other activities until the pain subsides is recommended. An over-the-counter, non-steroidal anti-inflammatory drug (NSAID), such as ibuprofen (Motrin®) or naproxen (Aleve® or Naprosyn®), might also be recommended to help reduce pain and inflammation. 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 may also help reduce inflammation and ease pain.
- Bracing - Additionally a brace or back support may be used to help stabilize the lower back and reduce pain. An exercise program and/or physical therapy will help increase pain-free movement and improve flexibility and muscle strength. We periodically take X-rays to determine if bone slippage persists.
- Physical therapy - Exercise strengthens the abdominal and/or back muscles thus minimizing bony movement of the spine. We generally recommend eight to 12 weeks of aggressive, daily stabilization exercises to achieve clinical improvement.
- Surgery - A surgical option may be necessary if the vertebra continues to slip or if the pain is not relieved by conservative treatment. Through surgery, we are able to stabilize the spine where the vertebra has slipped out of place and relieve the pain associated with an irritated nerve—all of which increases the person’s ability to function.