What is spondylolisthesis?
Spondylolisthesis is a condition in which one of the bones of the spine (vertebrae) slips out of place onto the vertebra below it. If it slips too much, the bone might press on a nerve, causing pain. Usually, the bones of the lower back are affected.
The word spondylolisthesis comes from the Greek words spondylos, which means "spine" or "vertebra," and listhesis, which means "to slip or slide."
What are the types of spondylolisthesis?
There are different types of spondylolisthesis. The more common types include.
- Congenital spondylolisthesis: Congenital means "present at birth." Congenital spondylolisthesis is the result of abnormal bone formation. In this case, the abnormal arrangement of the vertebrae puts them at greater risk for slipping.
- Isthmic spondylolisthesis: This type occurs as the result of spondylolysis, a condition that leads to small stress fractures (breaks) in the vertebrae. In some cases, the fractures weaken the bone so much that it slips out of place.
- Degenerative spondylolisthesis: This is the most common form of the disorder. With aging, the discs — the cushions between the vertebral bones — lose water, becoming less spongy and less able to resist movement by the vertebrae.
Less common forms of spondylolisthesis include:
- Traumatic spondylolisthesis, in which an injury leads to a spinal fracture or slippage.
- Pathological spondylolisthesis, which happens when the spine is weakened by disease — such as osteoporosis — an infection, or tumor.
- Post-surgical spondylolisthesis, which refers to slippage that occurs or becomes worse after spinal surgery.
How common is spondylolisthesis?
Spondylolisthesis is the most common cause of back pain in teens. Symptoms of spondylolisthesis often begin during the teen-age growth spurt. Degenerative spondylolisthesis occurs most often after age 40.
How is spondylolisthesis graded?
A radiologist determines the degree of slippage upon reviewing spinal X-rays. Slippage is graded I through IV:
- Grade I: 1% to 25% slip
- Grade II: 26% to 50% slip
- Grade III: 51% to 75% slip
- Grade IV: 76% to 100% slip
Generally, Grade I and Grade II slips do not require surgery and are treated medically. Grade III and Grade IV slips might require surgery if persistent, painful, slips are present.
What are the symptoms of spondylolisthesis?
Many people with spondylolisthesis have no symptoms and don't even know they have the condition. When symptoms do occur, low back pain is the most common. The pain usually 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 the 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.