Medical Necessity Determination for Spinal Bone Autograft (CPT 20936)
Spinal bone autograft (CPT 20936) is medically necessary for this patient undergoing C3-4 anterior cervical discectomy and fusion (ACDF) for severe cervical stenosis with myelopathy and cord compression. 1, 2
Primary Surgical Indication is Clearly Met
The patient meets all criteria for cervical laminectomy/fusion per institutional guidelines: documented myelopathy with objective neurological findings (hyperreflexia, clonus, positive Hoffman's signs, spastic gait), severe stenosis with cord compression on MRI showing cord edema at C3-4, failed 6 weeks of conservative therapy, and significant ADL limitations. 1, 3
The presence of increased signal within the compressed cord at C3-4 indicates cord edema and compressive myelopathy, representing potentially irreversible spinal cord injury that warrants urgent surgical decompression. 4, 3
Surgical intervention should not be delayed in this patient with evolving myelopathy and progressive balance dysfunction, as outcomes are better when symptoms have been present for less than one year, and this patient has had progressive worsening over the past year. 1, 5
Autograft is Standard of Care for Cervical Fusion
Autograft bone is explicitly considered medically necessary for spinal fusions by multiple authoritative sources and provides superior fusion rates compared to allograft alone. 1, 6
The American Association of Neurological Surgeons considers both autograft and allograft medically necessary for spinal fusions, with 97% fusion rates when combined with anterior plating. 1
Higher rates of fusion have been reported with autograft than allograft, particularly in multilevel reconstructions where autogenous strut grafts from the iliac crest and fibula achieve fusion rates of approximately 100%. 6
Autograft supplementation reduces pseudarthrosis risk in cervical fusion constructs, which is critical as pseudarthrosis was significantly associated with unsatisfactory pain outcomes (p < 0.001) in a long-term follow-up study of 108 patients. 1, 7
Institutional Guidelines Support Autograft Use
The institutional CPB guideline (Policy 0411) explicitly states that "allograft materials that are 100% bone are considered medically necessary" for spinal fusions, and this same principle applies to autograft bone, which is biologically superior to allograft. 1
The patient has already received certification for allograft codes (20930 - morselized allograft and 20931 - structural allograft), demonstrating institutional recognition that bone graft material is necessary for this fusion procedure. 1
The absence of specific CPB criteria for autograft does not indicate it is not medically necessary; rather, autograft is the gold standard against which allograft is compared. 6
Clinical Rationale for Autograft in This Case
In anterior cervical corpectomy and discectomy procedures, autograft bone material harvested during the decompression can be packed into cages or used as structural graft, achieving complete bony fusion in 100% of patients in one prospective study of 27 patients. 2
Using autograft bone material harvested during the ACC avoids complications associated with explantation of autograft material from other donor sites (e.g., iliac crest), while still providing the superior osteoinductive and osteoconductive properties of autogenous bone. 2
The combination of autograft with anterior plating represents the current standard of care for ACDF and provides stability while reducing the risk of graft failure and pseudarthrosis. 1, 7
Avoiding Common Pitfalls
Do not deny autograft simply because it is not explicitly listed in institutional guidelines when allograft is approved. Autograft is biologically superior to allograft and should be considered at least as medically necessary. 6
Do not require the surgeon to use only allograft when autograft is clinically preferable. The potential for a patient with a nonunion requiring additional operative treatment must be weighed against the potential for graft-related complications when choosing between autograft and allograft. 6
Recognize that the absence of specific MCG criteria for bone graft does not indicate lack of medical necessity. The MCG criteria focus on the primary decompression procedure, and bone graft is an integral component of fusion surgery that is universally accepted as standard of care. 1, 3
Supporting Evidence for Fusion in This Patient
Anterior decompression and arthrodesis with autogenous bone-grafting can be performed safely and is associated with a high rate of neurological recovery, functional improvement, and pain relief in patients who have cervical spondylotic myelopathy. 7
In a series of 108 patients with cervical spondylotic myelopathy managed with anterior decompression and arthrodesis using autogenous bone graft, the average Nurick grade improved from 2.4 preoperatively to 1.2 postoperatively, with 54 of 87 patients achieving complete recovery of motor deficits. 7
The strongest predictive factor for recovery from myelopathy is the severity of myelopathy before operative intervention—better preoperative neurological function is associated with better neurological outcome, making timely intervention with optimal fusion technique critical. 7