Grade 2 Anterolisthesis: Understanding the Condition
Grade 2 anterolisthesis means that one vertebra (spinal bone) has slipped forward over the bone below it by 25-50% of the width of the vertebral body. This is a moderate degree of slippage that can cause back pain, leg pain, and neurological symptoms depending on whether nerves are compressed 1.
What the Grading System Means
The severity of vertebral slippage is rated on a scale from 1 to 4 based on how far forward the bone has moved 1:
- Grade 1: 0-25% forward displacement (mild)
- Grade 2: 25-50% forward displacement (moderate)
- Grade 3: 50-75% forward displacement (severe)
- Grade 4: 75-100% forward displacement (very severe)
Common Locations and Causes
Anterolisthesis most commonly occurs at two locations in the lower spine 1:
- L5-S1 level: Between the fifth lumbar vertebra and the sacrum (tailbone area)
- L4-5 level: Between the fourth and fifth lumbar vertebrae
The forward slippage happens when the normal structures that hold the spine in alignment become damaged or weakened 1. This can occur from:
- Degenerative changes: Wear and tear of the facet joints (most common in women over 40 at L4-5) 1
- Isthmic defects: A fracture or defect in the pars interarticularis (a small bridge of bone in the back of the vertebra), most common at L5-S1 1
- Trauma: Injury from falls or accidents 2, 3
Symptoms You Might Experience
With Grade 2 anterolisthesis, patients commonly report 2:
- Lower back pain that may radiate down one or both legs
- Stiffness in the lower back
- Muscle tightness, particularly in the buttocks and thighs
- Difficulty walking, sitting, or standing for prolonged periods
- Altered posture and gait patterns
- Neurological symptoms if nerves are compressed (numbness, tingling, weakness)
Clinical Significance of Grade 2
Grade 2 represents a moderate slip that often requires treatment, particularly when combined with spinal stenosis (narrowing of the spinal canal) or nerve compression 4. Studies show that patients with symptomatic stenosis and spondylolisthesis who undergo surgical decompression and fusion achieve 93-96% excellent or good outcomes, compared to only 44% with decompression alone 5.
The presence of any degree of spondylolisthesis (including Grade 2) with symptomatic spinal stenosis is considered a Grade B indication for surgical fusion if conservative management fails 4, 5.
Important Diagnostic Considerations
Dynamic X-rays (flexion-extension views) are essential to assess the true degree of instability, as static images may underestimate or overestimate the actual slippage 6. In patients with hyperlordosis (excessive inward curve of the lower back), static radiographs may overestimate the degree of anterolisthesis, making dynamic imaging critical for accurate assessment 6.