Is L4 to S1 anterior lumbar interbody fusion medically indicated for a patient with lumbar radiculopathy, 2-3 mm retrolisthesis, minimal bilateral neural foraminal narrowing on L4 to L5, and mild to moderate left neural foraminal narrowing on L5 to S1?

L4-S1 Anterior Lumbar Interbody Fusion Is NOT Medically Indicated for This Patient

This patient does not meet criteria for lumbar fusion and should undergo decompression alone (discectomy/laminectomy) if surgery is pursued at all. The imaging findings show minimal to mild degenerative changes without documented instability, and the addition of fusion to primary discectomy for isolated disc herniation with radiculopathy is explicitly not recommended by current guidelines 1, 2.

Critical Analysis of Medical Necessity

Absence of Fusion Indications

The American College of Neurosurgery clearly states that lumbar fusion is not routine treatment following primary disc excision in patients with isolated herniated lumbar discs causing radiculopathy, unless instability is present 2. This patient lacks all of the specific circumstances that would justify fusion:

• No documented instability: The 2-3mm retrolisthesis at L4-L5 is minimal and does not constitute significant instability requiring fusion 1, 2
• No severe chronic axial back pain as primary complaint: The patient's predominant symptom is radicular pain down the right lower extremity, not isolated axial back pain 1
• Not a manual laborer: Fusion may provide benefit for heavy manual laborers returning to work, but this is not documented in this case 1
• No recurrent disc herniation: This is a primary presentation, not a revision scenario 1
• No severe degenerative changes or spondylolisthesis: The imaging shows mild disc height loss and minimal to moderate foraminal narrowing, not severe degeneration 1, 3

Evidence Against Routine Fusion

Multiple high-quality studies demonstrate that adding fusion to primary discectomy increases surgical complexity, prolongs surgical time, and potentially increases complication rates without proven medical necessity 2. The evidence is compelling:

• A large retrospective review of 3,956 cases showed patients with discectomy alone had better return-to-work rates (70%) compared to those with fusion (45%) 2, 4
• Level III evidence shows no improvement in functional outcomes with the routine use of fusion in conjunction with disc excision for primary lumbar disc herniation 1, 2, 4
• The 2014 guideline from the Journal of Neurosurgery concluded that "the increase in morbidity, cost, and potential complications associated with the use of fusion are not justified in routine situations" 1

Imaging Does Not Support Fusion

The MRI findings are relatively mild and do not demonstrate the severity of pathology that would warrant fusion:

• L4-L5: 2-3mm retrolisthesis (minimal), 4.5mm disc protrusion, mild central canal narrowing (9mm AP diameter), minimal bilateral foraminal narrowing 2, 4
• L5-S1: 4.5mm disc protrusion, mild to moderate left foraminal narrowing 2, 4

These findings represent isolated disc herniations with radiculopathy, the exact scenario where guidelines recommend against routine fusion 1, 2, 4.

Appropriate Surgical Management

If Surgery Is Pursued

Laminectomy and discectomy at L4-5 and L5-S1 without fusion is the appropriate surgical intervention if conservative management has truly failed and surgery is deemed necessary 2, 4. The decision to add fusion should only be made intraoperatively if significant instability is identified (>50% of facets need to be removed during decompression) 2.

Conservative Management Concerns

The patient reports that physical therapy and pain management "made symptoms worse," which raises questions about:

• Adequacy of conservative treatment trial (minimum 6 weeks recommended) 4
• Whether appropriate conservative modalities were exhausted 4
• Whether symptoms truly correlate with imaging findings 4

The patient can walk for 10 minutes before pain stops him, which suggests moderate functional limitation but not severe neurological compromise requiring urgent intervention 4.

Complications of Two-Level ALIF

The proposed L4-S1 ALIF carries significant additional risks compared to single-level procedures. Recent 2025 data shows that two-level ALIF patients were 10.9 times more likely to have in-hospital complications compared to one-level ALIF 5. Specific complications include:

• Intraoperative vascular injury: 11.1% in two-level vs. 1.5% in one-level ALIF 5
• Postoperative ileus: 7.4% in two-level vs. 0.0% in one-level 5
• Longer surgical time (147.3 vs. 124.6 minutes) and hospital stay (3.5 vs. 2.9 days) 5

Importantly, despite these increased risks, patient-reported outcome measures were comparable between one-level and two-level ALIF, with only minor improvements in alignment that did not translate to better functional outcomes 5.

Common Pitfalls to Avoid

• Performing fusion based on imaging findings alone: Degenerative changes on MRI do not necessarily correlate with pain and should not be the sole basis for surgical decision-making 3
• Misinterpreting minimal retrolisthesis as instability: 2-3mm retrolisthesis without dynamic instability on flexion-extension films does not meet criteria for fusion 1, 2
• Conflating radicular symptoms with need for fusion: Radiculopathy from disc herniation is treated with decompression, not fusion, unless specific additional criteria are met 1, 2, 4
• Ignoring the evidence on return-to-work rates: Fusion significantly impairs return to work compared to decompression alone (45% vs. 70%) 2, 4

Recommendation

Deny the requested L4-S1 anterior lumbar interbody fusion as not medically indicated. If surgical intervention is warranted based on failed conservative management and correlating clinical findings, the appropriate procedure would be decompression alone (laminectomy/discectomy at L4-5 and/or L5-S1) without fusion 1, 2, 4. The addition of fusion should only be considered if significant instability is identified intraoperatively (requiring removal of >50% of facets) 2.