Are spinal bone autograft (CPT code 20936) and spinal bone allograft (CPT code 20930) and insertion of a biomechanical device (CPT code 22853) medically necessary for a patient with lumbar spondylolisthesis and lumbar radiculopathy?

Medical Necessity Assessment for Spinal Bone Allograft, Autograft, and Biomechanical Devices in L2-4 TLIF

Direct Answer

The spinal bone allograft morsel (CPT 20930) and biomechanical devices/interbody cages (CPT 22853 x2) are medically necessary for this patient, but the separate spinal bone autograft (CPT 20936) is NOT medically necessary as an additional billable procedure.

Rationale for Interbody Fusion Devices (CPT 22853 x2)

The biomechanical devices (interbody cages) at L2-3 and L3-4 are medically necessary and meet established criteria. This patient has:

• Grade 1 anterolisthesis at L3-4 documented on imaging, representing structural instability that is a Grade B indication for fusion with interbody devices 1
• Moderate-to-severe stenosis at both L2-3 and L3-4 with neural compression of traversing nerve roots, meeting decompression criteria 1
• Failed comprehensive conservative management including 6+ weeks of physical therapy, NSAIDs, and epidural steroid injection with only 2 days of relief 1
• Adjacent segment disease above a prior L4-S1 fusion, which commonly requires surgical intervention 2

The TLIF approach with interbody cages is specifically appropriate here because interbody fusion techniques demonstrate fusion rates of 89-95% compared to 67-92% with posterolateral fusion alone in patients with degenerative disc disease and spondylolisthesis 2. The placement of graft within the load-bearing column provides biomechanical advantages and higher fusion rates 1.

Bone Graft Analysis: Allograft vs. Autograft

Allograft (CPT 20930) - MEDICALLY NECESSARY

Cadaveric allograft and demineralized bone matrix are considered medically necessary for spinal fusions according to established guidelines 2. For this two-level TLIF procedure:

• Local autograft harvested during laminectomy combined with allograft provides equivalent fusion outcomes and is the standard approach for multi-level TLIF 2
• Allograft materials that are 100% bone are considered medically necessary for spinal fusions regardless of implant shape 2
• Fusion rates of 89-95% are achievable with local autograft combined with allograft in instrumented TLIF procedures 2

Separate Iliac Crest Autograft (CPT 20936) - NOT MEDICALLY NECESSARY

The addition of separate iliac crest bone graft harvest is NOT medically necessary when adequate local autograft is available from the decompression. The evidence clearly demonstrates:

• Local autograft from lamina and spinous processes combined with allograft is sufficient for single and two-level TLIF procedures 1, 2
• Iliac crest harvest is associated with donor-site pain in 58-64% of patients at 6 months, plus increased operative time, blood loss, and potential chronic pain 2
• No significant difference in fusion rates exists between local autograft/allograft combinations versus iliac crest autograft in instrumented TLIF 1
• Grade C evidence supports β-tricalcium phosphate/local autograft as equivalent to iliac crest bone with comparable fusion rates and clinical outcomes 2

In the Kim et al. prospective randomized study, local autograft from lamina/spinous processes placed in interbody cages achieved 95% fusion rates, and the addition of iliac crest harvest only resulted in donor site pain, increased blood loss, and longer operative time without improving fusion rates 1.

Critical Clinical Context

This 63-year-old patient with BMI 42.06 and prior L4-S1 fusion at age 15 presents with:

• Adjacent segment stenosis at L2-3 and L3-4 with moderate canal stenosis and neural compression 2
• Grade 1 anterolisthesis at L3-4 measuring 8mm with severe disc height loss 1
• Progressive neurological symptoms including weakness requiring cane assistance and radiculopathy 1
• Failed epidural steroid injection providing only 2 days of relief 1

The combination of spondylolisthesis with stenosis requiring decompression represents a clear Grade B indication for fusion 1. Patients with stenosis and degenerative spondylolisthesis who undergo decompression with fusion achieve 96% excellent/good outcomes versus only 44% with decompression alone, with statistically significant reductions in back pain (p=0.01) and leg pain (p=0.002) 2.

Common Pitfalls to Avoid

Do not approve separate iliac crest autograft harvest (CPT 20936) when:

• Adequate local bone is available from two-level laminectomy 2
• Allograft extenders are being used 2
• The procedure is already instrumented with pedicle screws providing stability 1

The morbidity of iliac crest harvest is not justified when local autograft combined with allograft achieves equivalent fusion rates without the 58-64% incidence of donor site pain 2.

Recommendation Summary

APPROVE:

• CPT 22853 x2 (biomechanical devices/interbody cages at L2-3 and L3-4)
• CPT 20930 (allograft morsel as bone graft extender)

DENY:

• CPT 20936 (separate iliac crest autograft harvest) - not medically necessary when adequate local autograft from decompression is available and allograft extenders are being used 1, 2