Retrolisthesis is a spinal condition involving a vertebra slipping backward relative to the vertebra positioned directly below it. This displacement is considered a joint dysfunction that affects the alignment and stability of the spine. Misalignment of the spine can potentially impact the nerves and soft tissues that maintain spinal function.
Anatomical Definition and Contrast
The spine is a column of bones, the vertebrae, which are stacked and separated by intervertebral discs. These discs act as cushions and shock absorbers, held in place by strong ligaments. Retrolisthesis occurs when one of these vertebrae shifts in a posterior direction along the plane of the disc below it.
This condition is distinct from spondylolisthesis, which involves a vertebra slipping forward. While both terms describe a vertebral displacement, the direction of the slip is opposite. Retrolisthesis most often affects the cervical spine (neck region) and the lumbar spine (lower back region) because these areas are subjected to the most mechanical stress. The thoracic spine, stabilized by the rib cage, is less frequently affected.
Primary Causes and Contributing Factors
The backward slippage of a vertebra is a consequence of instability in the spinal segment, often caused by age-related deterioration. Degenerative disc disease is a leading factor, where the intervertebral discs lose water content and elasticity, causing them to shrink. This disc thinning decreases the space between vertebrae, destabilizing the connection and allowing the backward shift to occur.
Facet joint arthritis contributes to retrolisthesis. The facet joints are small paired joints at the back of the spine that guide and limit spinal movement. Arthritis in these joints can lead to degeneration and dysfunction, compromising the joint’s ability to maintain vertebral alignment. Acute trauma can also cause instability and displacement. Factors like weakened core muscles, infections, and congenital defects may contribute by reducing spinal support and stability.
Grading and Classification of Severity
Clinicians use a grading system to classify the severity of retrolisthesis based on the extent of the backward displacement. This measurement is performed using lateral X-ray images of the spine. The system assesses the percentage of posterior displacement of one vertebral body relative to the one below it.
The classification uses four grades, with Grade 1 being the least severe and Grade 4 representing the most severe displacement. Grade 1 involves a slippage of up to 25% of the vertebral body. Grade 2 ranges from 25% to 50% displacement, and Grade 3 is classified as 50% to 75% slippage. Grade 4 is defined by displacement between 75% and 100%. This grading helps assess the spinal segment’s stability and guides treatment decisions.
Symptom Recognition and Treatment Pathways
The symptoms associated with retrolisthesis depend on the degree of slippage and whether the displacement is irritating or compressing nearby nerves. Common symptoms include localized pain in the affected area, muscle stiffness, and a limited range of motion. If the misaligned vertebra encroaches upon the spinal cord or nerve roots, neurological symptoms may arise.
Nerve compression can result in radiculopathy, causing pain, tingling, numbness, or muscle weakness that radiates into the extremities. For instance, cervical retrolisthesis may cause symptoms in the arms and hands, while lumbar retrolisthesis may cause issues in the buttocks, thighs, and legs. In severe cases, compression can lead to problems with coordination, balance, and the ability to walk.
Management of retrolisthesis begins with conservative care. Initial treatment focuses on reducing inflammation and pain through the use of non-steroidal anti-inflammatory drugs (NSAIDs) and muscle relaxers. Physical therapy is a central component, aiming to strengthen the core and spinal muscles to improve stability and correct posture. Many patients find that symptoms resolve within six to eight weeks with consistent conservative treatment.
If conservative methods fail to provide relief, or if the patient presents with severe neurological deficits or high-grade instability, surgical intervention may become necessary. The goals of surgery are to minimize the slippage, stabilize the spine, and relieve pressure on the compressed nerves. Common surgical procedures include spinal fusion, which permanently connects two or more vertebrae to prevent movement, or decompression surgery to create more space for the affected neural tissue.