What is the percentage chance of a successful outcome after posterior instrumented lumbar fusion for a typical adult (age 40‑70) with a Grade I‑II L5 anterolisthesis causing only chronic low‑back pain and no radiculopathic symptoms?

Success Rates for Spinal Fusion in L5 Anterolisthesis with Isolated Chronic Back Pain

For Grade I–II L5 anterolisthesis causing only chronic low-back pain without radiculopathy, posterior instrumented lumbar fusion shows approximately 76–85% patient satisfaction at long-term follow-up, but current guidelines do not strongly support fusion for isolated axial pain without documented instability or radiculopathy. 1, 2

Critical Distinction: Isolated Axial Pain vs. Radiculopathy

The American Association of Neurological Surgeons explicitly states that lumbar fusion should NOT be used as first-line therapy for adults with isolated axial low-back pain when there is no radiographic instability, deformity, or progressive neurologic deficit. 2 This is the most important consideration for your clinical scenario.

Evidence Against Routine Fusion for Isolated Back Pain

• Fusion is recommended only for patients with disabling low-back pain due to one- or two-level degenerative disease AND documented instability or deformity; isolated axial pain alone does not meet these criteria. 2

• The guidelines state that evidence is insufficient to support routine fusion for intractable low-back pain that lacks spinal stenosis or spondylolisthesis with radicular symptoms. 2

• There does not appear to be evidence to support the routine use of fusion at the time of an index discectomy operation, and the increase in morbidity, cost, and potential complications associated with fusion are not justified in routine situations. 1

Success Rates When Fusion IS Performed

When fusion is performed in patients with low-grade spondylolisthesis (regardless of symptom type), the data shows:

Satisfaction Rates

• 76% satisfaction at 6 years for discectomy alone versus 85% for discectomy plus fusion in patients with disc herniations. 1

• 93% of patients with spondylolisthesis treated with posterior interbody fusion reported satisfaction with their condition at 14-month follow-up. 1

• 92% of patients with recurrent disc herniations with instability and/or axial low-back pain improved after fusion surgery, with 90% very satisfied with results. 1

Important Caveat on Deterioration

• Recent data from the Quality Outcomes Database shows that 12% of patients reported deterioration in back pain scores at 2 and 5 years postoperatively. 3

• Patients with better (less severe) back pain scores at baseline were MORE likely to report deterioration in back pain scores at 2 and 5 years postoperatively. 3 This is a critical finding that directly applies to your question about isolated back pain without radiculopathy.

• There appeared to be a trend toward deterioration in those who underwent decompression alone without fusion, though this was not definitive. 3

Mandatory Conservative Management Requirements

Before ANY consideration of fusion for isolated axial pain, patients must complete:

• Intensive, supervised physical-therapy program lasting a minimum of 6 weeks. 2

• Cognitive-behavioral therapy as part of the pre-surgical conservative regimen. 2

• Fusion performed without documented failure of comprehensive conservative therapy (minimum 3–6 months of supervised PT ± CBT) is not supported by guidelines. 2

Specific Indications That Would Support Fusion

Fusion may be appropriate in the following scenarios (which go beyond isolated axial pain):

• Documented spondylolisthesis of any grade on imaging WITH radiculopathy. 2

• Manual-labor workers with significant chronic axial back pain AND disc herniation with radiculopathy. 2

• Severe degenerative changes accompanied by chronic axial pain AND radiographic evidence of instability. 2

• Recurrent disc herniation when associated with instability or persistent axial pain. 2

Psychosocial Factors Affecting Outcomes

Active worker's compensation claims or pending litigation are strongly associated with poor results. 4 In one series, all 13 patients involved in worker's compensation claims or pending litigation had fair or poor results, while 9 of 11 patients without such issues had good or excellent results. 4

Clinical Algorithm for Decision-Making

Step 1: Verify the Clinical Presentation

• Confirm that pain is truly isolated axial low-back pain without radiculopathy, progressive neurologic deficit, or cauda equina symptoms. 2

• Exclude documented instability on dynamic flexion-extension imaging. 2

• Assess for psychosocial factors (worker's compensation, litigation, baseline pain severity). 3, 4

Step 2: Implement Comprehensive Conservative Management

• Minimum 6 weeks of formal, supervised physical therapy focusing on core strengthening. 2, 5

• Cognitive-behavioral therapy. 2

• Activity modification (remaining active rather than bed rest). 5

• Pain management with NSAIDs and heat/cold therapy. 5

• Total duration: 3–6 months before surgical consideration. 2

Step 3: Reassess After Conservative Failure

• If symptoms persist after 3–6 months of comprehensive conservative management, obtain dynamic flexion-extension radiographs to document instability. 2

• Consider advanced imaging (MRI) only if not already obtained. 5

• Reassess for development of radicular symptoms or neurologic deficits. 5

Step 4: Surgical Consideration (Only If Criteria Met)

• Fusion should be considered ONLY if there is documented instability, spondylolisthesis WITH radiculopathy, or when extensive decompression might create instability. 2

• For isolated axial pain with Grade I–II anterolisthesis but no radiculopathy, the evidence does NOT support routine fusion. 2

Critical Pitfalls to Avoid

• Operating on patients with less severe baseline symptoms increases risk of deterioration. 3 Patients with better back pain scores at baseline are paradoxically more likely to report worsening at long-term follow-up.

• Fusion without adequate conservative management trial (minimum 3–6 months) is not guideline-supported. 2

• Ignoring psychosocial factors (worker's compensation, litigation) leads to poor outcomes regardless of surgical technique. 4

• Assuming that radiographic findings (anterolisthesis) automatically justify fusion—clinical correlation and symptom pattern are paramount. 2, 5

Bottom Line for Your Specific Question

For a typical adult (age 40–70) with Grade I–II L5 anterolisthesis causing ONLY chronic low-back pain without radiculopathic symptoms:

• Success rates of 76–85% satisfaction have been reported when fusion is performed, but these studies included mixed populations. 1

• Current guidelines do NOT support routine fusion for this indication. 2

• Patients with less severe baseline pain (isolated axial pain without radiculopathy) are at HIGHER risk of deterioration after surgery. 3

• Comprehensive conservative management for 3–6 months is mandatory before any surgical consideration. 2

• If surgery is pursued despite guideline recommendations, realistic expectations should be set: approximately 12% of patients may experience deterioration in back pain scores at long-term follow-up, with higher risk in those with less severe baseline symptoms. 3