Is spinal bone autograft (CPT code 20936) and bone marrow aspirate bone grafting (CPT code 20939) medically necessary for a patient with severe cervical stenosis?

Medical Necessity Determination for Spinal Bone Autograft and Bone Marrow Aspirate

Spinal bone autograft (CPT 20936) is medically necessary for this patient undergoing C6-C7 ACDF, as autograft remains the gold standard for cervical fusion with superior fusion rates compared to alternatives, particularly in patients with severe stenosis and cord impingement requiring definitive surgical stabilization. 1, 2, 3

Rationale for Autograft in This Clinical Scenario

Primary Indication Support:

• This 46-year-old patient has severe cervical stenosis at C6-C7 with cord impingement, early myelopathy, and radiculopathy—all absolute indications for surgical decompression and fusion 4
• The American Association of Neurological Surgeons recommends autograft bone harvested from the iliac crest as the gold standard for cervical fusion procedures due to its osteoinductive, osteoconductive, and osteogenic properties 2
• Autograft has demonstrated fusion rates of up to 97% for single-level ACDF procedures, significantly higher than many alternatives 2

Clinical Factors Favoring Autograft:

• The patient has advanced degenerative disc disease with kyphosis at C6-C7 that does not reduce on extension, indicating structural instability requiring robust fusion 2
• Cord impingement with 6.8 mm of available space represents severe stenosis requiring decompression with reliable fusion to prevent recurrent compression 4
• The presence of early myelopathy indicates progressive neurological compromise that necessitates definitive surgical treatment with the highest probability of successful fusion 4

Evidence Quality and Strength

Guideline-Level Evidence:

• The Journal of Neurosurgery guidelines (representing American Association of Neurological Surgeons recommendations) provide Class II evidence supporting autograft for 1- or 2-level ACDF with strength of recommendation C 1
• Autograft has yielded higher fusion rates in both 1- and 2-level procedures compared to alternatives in meta-analyses 1, 5
• The use of autograft eliminates concerns about disease transmission or immunologic rejection that might occur with allograft materials 5

Comparative Outcomes:

• Allograft bone has shown lower fusion rates in multilevel procedures (89.5% vs 100% for autograft) and greater subsidence (3.0 mm vs 1.8 mm for autograft, p=0.005) 2
• While allograft shows similar results in some single-level procedures, the patient's severe pathology with cord impingement favors the more reliable autograft option 3, 6
• Recombinant human bone morphogenic protein-2 (rhBMP-2) carries a complication rate of 23-27% compared to 3% for standard approaches and is not recommended for routine cervical use 1, 2

Bone Marrow Aspirate (CPT 20939) Consideration

Limited Direct Evidence:

• While specific guidelines for bone marrow aspirate in cervical fusion are not provided in the evidence, bone marrow aspirate is recognized as a bone graft extender with biological activity 1
• One study showed all 19 patients treated with autologous growth factors (AGF) derived from concentrated platelets mixed with autograft achieved successful fusion, though this provides only Class III evidence 1

Clinical Context:

• Given the patient's severe stenosis with cord impingement and early myelopathy, maximizing fusion potential is critical to prevent catastrophic neurological deterioration 4
• Bone marrow aspirate may serve as an adjunct to enhance the osteogenic potential of the primary autograft, though it should not replace structural autograft 1
• The evidence supports bone marrow aspirate as safe when used as a graft extender, though its efficacy has not been definitively compared to autograft alone 1

Important Clinical Caveats

Donor Site Morbidity:

• Autograft harvest may cause donor site morbidity, but this must be weighed against the higher fusion rates and lower subsidence rates, particularly given this patient's severe pathology 2
• The patient's relatively young age (46 years) and need for definitive fusion favor accepting donor site risk for superior fusion outcomes 6

Smoking Status:

• Smoking status should be assessed, as it can negatively impact fusion rates, particularly with allograft materials 2
• If the patient is a smoker, this further supports the use of autograft over allograft 6

Long-term Considerations:

• Achieving solid fusion is critical for long-term outcomes in patients with cord compression and myelopathy that has failed conservative management 2
• Untreated severe cervicomedullary compression carries a mortality rate of 16%, and long periods of severe stenosis can lead to irreversible neurological deficits 4
• Approximately 97% of patients have some recovery of symptoms after surgery, but this depends on achieving solid fusion 4

Final Determination

CPT 20936 (Spinal Bone Autograft) is medically necessary for this patient's C6-C7 ACDF given the severe stenosis with cord impingement, early myelopathy, and the superior fusion rates demonstrated with autograft compared to alternatives. 1, 2, 3

CPT 20939 (Bone Marrow Aspirate) has limited specific evidence for cervical fusion but may be considered as an adjunct to enhance fusion potential in this high-risk scenario with cord compression and myelopathy, though it should not replace structural autograft. 1