Is total disc arthroplasty (TDA) anterior single lumbar medically necessary for a patient with degeneration of intervertebral disc of lumbar region with discogenic back pain and lower extremity pain, given the last MRI was performed 12 months ago?

Total Disc Arthroplasty is NOT Medically Necessary Due to Outdated Imaging

The requested total disc arthroplasty (TDA) does not meet medical necessity criteria because the MRI was performed 12 months ago (December 2024), exceeding the 6-month imaging recency requirement specified in the Aetna clinical policy bulletin. This imaging timeline violation is a critical exclusion criterion that supersedes all other clinical considerations.

Primary Issue: Imaging Recency Requirement

The Aetna policy explicitly requires that "single level disease has been confirmed by a recent (within 6 months) x-ray and MRI or CT." 1 This is not an arbitrary administrative requirement—it serves essential clinical purposes:

• Disease progression assessment: Degenerative disc disease is dynamic, and significant changes can occur over 6-12 months that would alter surgical candidacy 2
• Accurate surgical planning: Current imaging is necessary to confirm that anatomical relationships, disc height, and endplate integrity remain appropriate for device placement
• Exclusion of new contraindications: The 12-month interval allows time for development of conditions that would contraindicate TDA, such as progressive stenosis, facet degeneration, or endplate changes

Critical Imaging Findings That Require Current Evaluation

The December 2024 MRI demonstrated several findings that necessitate updated imaging before proceeding:

• Moderate to severe bilateral foraminal stenosis at L5-S1: This approaches a contraindication for TDA, as the policy excludes "lumbar nerve root compression or at least moderate lateral recess or foraminal stenosis" 1
• Moderate left foraminal stenosis at L4-L5: Additional level involvement that could have progressed 1
• Mild central spinal canal stenosis at L5-S1: While currently mild, this could progress to moderate stenosis (an absolute contraindication) over 12 months 1
• Residual discogenic endplate marrow edema at L5-S1: Though decreased from prior, endplate integrity is critical for device fixation and requires current assessment 1

Why This Timeline Matters Clinically

The American College of Radiology guidelines emphasize that degenerative findings are common in asymptomatic patients and can change significantly over time. 2 Specifically:

• Disc abnormalities in symptomatic patients can show regression or progression within months 2
• 84% of patients with lumbar imaging abnormalities had unchanged or improved findings after symptoms developed, highlighting the dynamic nature of these conditions 2
• Repeat imaging is necessary when clinical decision-making depends on current anatomical status 2

Additional Concerns Beyond Imaging Timeline

Even with updated imaging, this case presents borderline candidacy issues:

Stenosis severity: The documented "moderate to severe bilateral foraminal stenosis" at L5-S1 is problematic, as TDA is contraindicated in patients with "lumbar nerve root compression or at least moderate lateral recess or foraminal stenosis" 1. The policy language suggests moderate stenosis is an exclusion criterion.

Multi-level involvement: While the surgical plan targets L5-S1, the MRI shows degenerative changes at L3-L4, L4-L5, and L5-S1, raising concerns about "symptomatic degenerative disc disease at more than one level" 1

Physical examination inconsistency: The examination documents "normal thoracic and lumbar motor strength," "normal light touch and pinprick sensation," and "normal deep tendon reflexes"—yet the patient reports significant pain and functional impairment. This disconnect warrants careful evaluation of whether the pathology is truly discogenic 2

Required Next Steps

1. Obtain current MRI (within 6 months of proposed surgery date of 12/16/2025) to:

   • Reassess foraminal stenosis severity at L5-S1
   • Confirm central canal dimensions remain >8mm
   • Evaluate endplate integrity and disc height (must be >2mm)
   • Exclude progression of stenosis to moderate central level 1

2. Comprehensive stenosis evaluation: If updated imaging confirms moderate-to-severe foraminal stenosis persists, TDA is contraindicated and alternative treatments (decompression, fusion, or continued conservative management) should be considered 1

3. Consider alternative diagnosis: Given normal neurological examination despite reported pain, evaluation for non-discogenic pain sources may be warranted before proceeding with any surgical intervention 2

Evidence on TDA Efficacy

While TDA has demonstrated effectiveness for appropriately selected patients with single-level degenerative disc disease—with 74% improvement in back pain and 67% improvement in Oswestry Disability Index scores at 2 years 3—patient selection criteria exist for valid clinical reasons. Recent comparative data shows TDA outcomes at L5-S1 may be inferior to fusion due to biomechanical factors at this level 4. The presence of significant foraminal stenosis further complicates the risk-benefit analysis.

Common Pitfalls to Avoid

• Assuming old imaging remains valid: Degenerative conditions evolve, and 12-month-old imaging cannot reliably guide current surgical decision-making 2
• Overlooking stenosis severity: "Moderate to severe" foraminal stenosis language in the radiology report suggests this may already exceed policy thresholds 1
• Proceeding without addressing examination-symptom mismatch: Normal neurological examination with severe reported symptoms warrants additional evaluation before irreversible surgical intervention 2