Understanding Cervical Vertebral Slippage: Anterolisthesis and Retrolisthesis
Grade 1 anterolisthesis of C3 on C4 means the C3 vertebra has slipped forward relative to C4 by 2-3 mm, while grade 1 retrolisthesis of C4 on C5 means C4 has slipped backward relative to C5 by 2-3 mm. These findings represent mild degenerative changes in cervical spine alignment that are relatively common, particularly in individuals over 50 years of age 1, 2.
Definition and Grading
Anterolisthesis refers to forward slippage of one vertebral body relative to the vertebra below it, while retrolisthesis describes backward slippage 3, 2.
The grading system classifies displacement severity:
- Grade 1: 2-3 mm of displacement (mild) 4, 5
- Grade 2: Greater than 3 mm displacement (moderate to severe) 4, 2
In your case, both findings are grade 1, representing the mildest category of vertebral slippage 4.
Clinical Significance and Natural History
Grade 1 cervical spondylolisthesis (both anterolisthesis and retrolisthesis) typically follows a stable natural history and rarely progresses to cause neurological injury 1. A longitudinal study following patients for 2-7 years found that cervical degenerative spondylolisthesis remained stable over time, with none progressing to dislocation or neurological deterioration 1.
Key Clinical Points:
- Prevalence: Cervical degenerative spondylolisthesis occurs in approximately 3.9% of patients, most commonly at C3-C4 and C4-C5 levels—exactly where your findings are located 1, 2
- Retrolisthesis is more common than anterolisthesis in the cervical spine, with a ratio of approximately 3.5:1 1
- Grade 1 findings have minimal clinical significance as a solitary finding, with substantial overlap with normal age-related degenerative changes 4
Relationship to Symptoms
The presence of grade 1 spondylolisthesis does not automatically indicate symptomatic disease 1, 6. In one study of cervical spondylolisthesis patients, 41% had no cervical symptoms at baseline despite radiographic findings 1.
Important distinction: While anterolisthesis tends to have greater impact on spinal cord compression when severe (≥3.5 mm), grade 1 anterolisthesis rarely causes significant neural compression 2. Your grade 1 findings are below the threshold typically associated with myelopathy 2.
Biomechanical Considerations
Retrolisthesis at C4-C5 combined with anterolisthesis at C3-C4 suggests compensatory motion patterns in the cervical spine related to disc degeneration 2, 5. This pattern indicates:
- Greater mobility of upper cervical segments may compensate for advanced disc degeneration at lower levels 2
- Patients with retrolisthesis tend to have larger T1 slope angles, affecting overall cervical sagittal balance 5
- The combination of both types of slippage at adjacent levels reflects degenerative cascade changes 2
Assessment Accuracy
Critical pitfall: Static radiographs in hyperlordotic positioning can overestimate the degree of spondylolisthesis 7. Dynamic flexion-extension radiographs are necessary to assess true segmental instability and avoid overestimation 7.
Dynamic instability is defined as translation greater than 2 mm on flexion-extension views 1. Only 37% of patients with baseline spondylolisthesis demonstrate this degree of dynamic motion 1.
Prognosis and Monitoring
The natural history is reassuring: Among patients with initial dynamic translation less than 2 mm, only 18% progressed to greater than 2 mm of motion over 2-8 years, and none experienced clinical worsening 1.
For grade 1 findings specifically:
- Progression to higher grades is uncommon 1
- Neurological complications are rare 1
- Most patients remain stable or asymptomatic over long-term follow-up 1
If symptoms are present (neck pain, radiculopathy), conservative management with multimodal chiropractic care, physical therapy, or other non-surgical approaches is typically successful 3. Surgical intervention is reserved for cases with severe displacement (grade 2 or higher), documented instability on dynamic imaging, or progressive neurological deficits 4.