Is a lumbar arthrodesis (22558) with allograft morselized bone (20930) medically necessary for a patient with L5-S1 degenerative disc disease (DDD), lumbago, and lumbar radiculopathy, who has failed conservative therapy and has moderate to severe neural compression?

Medical Necessity Assessment for L5-S1 ALIF with Allograft (CPT 22558,20930)

Based on the available evidence and insurance criteria, the requested L5-S1 anterior lumbar interbody fusion (ALIF) with allograft bone graft does NOT meet medical necessity criteria because the patient has only MILD neuroforaminal narrowing on MRI, which fails to satisfy the requirement for moderate-to-severe stenosis needed to justify fusion surgery. 1, 2

Critical Deficiency in Meeting Insurance Criteria

The insurance policy explicitly requires "central/lateral recess or foraminal stenosis graded as moderate, moderate to severe or severe; not mild or mild to moderate" on advanced imaging studies. 2 This patient's MRI demonstrates:

• L4-5: Mild left neuroforaminal narrowing
• L5-S1: Mild bilateral neuroforaminal narrowing
• Small diffuse disc bulge with only mild impression on thecal sac

This imaging does not meet the threshold for surgical intervention. 1, 2

Evidence Against Fusion for Primary Disc Herniation with Radiculopathy

Guideline Recommendations

The American Association of Neurological Surgeons and American College of Neurosurgery provide clear guidance against routine fusion in this clinical scenario:

• Fusion is NOT recommended for primary disc herniation with radiculopathy in the absence of instability, deformity, or recurrent herniation with chronic axial pain. 3, 2

• Level III evidence demonstrates that routine posterolateral fusion does not improve functional outcomes compared to discectomy alone in patients with primary disc herniations (70% return to work with discectomy alone vs 45% with fusion). 3

• The addition of fusion increases surgical complexity, operative time, and complication rates without proven medical necessity for isolated disc pathology. 3

Specific Contraindications in This Case

This patient lacks ALL of the following conditions that would justify fusion: 2

• No documented spinal instability on imaging
• No spinal deformity (scoliosis, spondylolisthesis)
• No recurrent disc herniation (this is primary pathology)
• No evidence of severe chronic axial back pain as primary complaint (radiculopathy is predominant)

Allograft Medical Necessity (CPT 20930)

The allograft bone graft code (20930) cannot be deemed medically necessary when the primary fusion procedure itself does not meet medical necessity criteria. 3

While cadaveric allograft is considered medically necessary for spinal fusions when appropriately indicated, the guidelines specify this applies to cases where fusion is already justified. 3 Since the underlying fusion procedure (22558) does not meet criteria, the adjunctive bone graft material is also not medically necessary.

Alternative Treatment Pathway

What This Patient Actually Needs

Given the mild stenosis and failed single epidural injection, the appropriate next steps include: 2, 4

• Repeat epidural steroid injection (only 2 weeks of relief from single L5-S1 TESI suggests inadequate trial; typically 2-3 injections spaced 2-4 weeks apart are recommended) 5, 4

• Structured physical therapy program (patient only completed 1 session which was "not tolerable" - this does not constitute adequate conservative management) 4

• Multimodal pain management optimization (current medications include only NSAIDs and muscle relaxants; no mention of neuropathic pain agents like gabapentin or pregabalin) 4

• Consider spinal cord stimulation or DRG stimulator trial if conservative measures continue to fail 2

Conservative Management Requirements

The patient has NOT completed adequate conservative therapy: 4, 6

• Only 1 physical therapy session (minimum 6-12 weeks of structured PT typically required)
• Only 1 epidural injection with 2 weeks relief (series of 2-3 injections recommended)
• No trial of neuropathic pain medications documented
• No comprehensive rehabilitation program attempted

When Would Fusion Be Appropriate?

Fusion at L5-S1 would be medically necessary if: 3, 2

• Imaging showed moderate-to-severe or severe foraminal stenosis (not mild as currently documented)
• Documented spinal instability on flexion-extension radiographs (>4mm translation or >10° angular motion)
• Recurrent disc herniation after prior discectomy with persistent symptoms
• Associated spondylolisthesis requiring stabilization
• Manual laborer with significant preoperative axial low-back pain as primary complaint (Level IV evidence supports fusion in this specific subset) 3

Common Pitfalls to Avoid

Performing fusion based solely on degenerative imaging findings without meeting clinical and radiographic severity thresholds leads to: 2

• Failed back surgery syndrome (3-40% incidence of persistent postoperative pain) 1
• Increased costs without improved outcomes 2
• Higher complication rates compared to decompression alone 3
• Adjacent segment degeneration requiring future surgery

Modic type II changes alone do not justify fusion - these represent fatty marrow replacement and are commonly seen in asymptomatic individuals. 3

Recommendation

DENY authorization for CPT 22558 (ALIF) and CPT 20930 (allograft) as NOT medically necessary. The patient requires completion of adequate conservative management including structured physical therapy (minimum 6-12 weeks), repeat epidural steroid injections (series of 2-3), and optimization of medical management with neuropathic pain agents before any surgical intervention could be considered. 1, 2, 4 Even with completed conservative care, the mild stenosis on imaging does not meet the moderate-to-severe threshold required by policy criteria. 2