Anterolisthesis is a common spinal condition characterized by the forward displacement of one vertebral body over the one directly beneath it. This misalignment most frequently occurs in the lumbar spine, or lower back. The condition is typically discovered during diagnostic imaging like X-rays, which measure the extent of the slippage. Measuring this forward shift is paramount for determining severity and guiding medical management.
What is Anterolisthesis?
Anterolisthesis is a type of spondylolisthesis, the general term for any vertebral slippage. The lumbar spine, particularly at the L4/L5 and L5/S1 segments, is the most common site for this forward movement. This structural instability can compress nearby nerve roots or the spinal cord, causing associated symptoms.
The causes of anterolisthesis are categorized into two main groups. Isthmic anterolisthesis is often seen in younger individuals and is caused by a defect or stress fracture in the pars interarticularis. Degenerative anterolisthesis is more common in older adults and results from chronic wear and tear on the spinal joints and discs. Regardless of the cause, medical professionals must measure and classify the resulting forward translation of the vertebral body.
Quantifying Severity: The Meyerding Grading System
The standard method used to classify the severity of anterolisthesis is the Meyerding Grading System. This system measures the percentage of the superior vertebral body that has slipped forward relative to the vertebra below it. Classification requires drawing lines on a lateral X-ray image to establish boundaries and calculate the amount of forward overhang.
The Meyerding system defines severity across five distinct grades using percentage measurements.
Meyerding Grades
- Grade I: 0 to 25% forward displacement (mildest form).
- Grade II: 26% to 50% slippage.
- Grade III: 51% to 75% slippage.
- Grade IV: 76% to 100% slippage.
- Grade V: Complete dislodgement of the vertebra (spondyloptosis).
Interpreting a 10 mm Slip and Associated Symptoms
The 10 mm measurement is an absolute distance that must be converted into a percentage for Meyerding grading. The average anterior-posterior width of a typical lumbar vertebral body (L4 or L5) ranges from 30 mm to 40 mm. Using this range, a 10 mm slip equates to a displacement of about 25% to 33% of the vertebral body width.
Based on this calculation, a 10 mm anterolisthesis generally falls into the high end of Grade I or the low end of Grade II. This range is considered a low-grade slip, clinically regarded as mild to moderate in severity. Symptoms frequently include localized chronic lower back pain that may worsen with activity or prolonged standing.
The forward movement of the vertebra can narrow the space for spinal nerves, causing neurological symptoms. Patients with a low-grade slip may experience mild radiculopathy, described as pain, numbness, or tingling radiating into the buttocks or legs. This is commonly known as sciatica, occurring when nerve roots are irritated by the misaligned bone structure. Stiffness in the lower back and tight hamstring muscles are also reported symptoms.
Treatment Approaches Based on Grade
Treatment for anterolisthesis is guided by the Meyerding grade and the severity of the patient’s symptoms. For low-grade slips like a 10 mm displacement (typically Grade I or low Grade II), conservative management is the initial and most common approach. This non-surgical treatment focuses on pain management and improving spinal stability.
The cornerstone of conservative care involves physical therapy designed to strengthen the core and lower back muscles for natural spinal support. Other non-operative methods include nonsteroidal anti-inflammatory drugs (NSAIDs) and activity modification. Epidural steroid injections may be used for persistent nerve-related pain, providing temporary relief by reducing inflammation around the affected nerve roots.
Surgical intervention is reserved for higher-grade slips (Grade III and above) or for lower-grade slips that fail to respond to conservative treatment over many months. Surgery, often involving spinal fusion and decompression, is considered for debilitating pain, progressive neurological deficits, or instability. The goal of surgery is to stabilize the spinal segment and relieve pressure on compressed nerves.