Is a spinal bone autograft (Spinal Bone Autograft) medically necessary for a patient undergoing laminectomy and transforaminal lumbar interbody fusion?

Medical Necessity of Spinal Bone Autograft for TLIF

Spinal bone autograft (CPT 20936) is NOT medically necessary for a 59-year-old patient undergoing laminectomy and transforaminal lumbar interbody fusion, as local autograft harvested during the laminectomy and facetectomy combined with allograft or bone graft substitutes provides equivalent fusion outcomes without the additional morbidity of separate autograft harvesting. 1

Evidence Against Routine Spinal Bone Autograft Harvesting

The American Association of Neurological Surgeons explicitly states that local autograft harvested during laminectomy combined with allograft provides equivalent fusion outcomes and is already approved for single-level TLIF procedures. 1 This eliminates the need for separate autograft harvesting procedures that add operative time, blood loss, and donor site morbidity.

• Multiple alternative bone graft options with comparable fusion rates (89-95%) and clinical outcomes are available, making harvesting of additional spinal bone autograft unnecessary 1, 2
• Iliac crest bone graft harvesting is associated with donor-site pain in 58-64% of patients at 6 months post-operatively, plus additional morbidity including increased operative time and blood loss 1

Superior Alternatives to Spinal Bone Autograft

Local Autograft Combined with Bone Graft Extenders

Grade C evidence supports the use of β-tricalcium phosphate combined with local autograft as a substitute for autologous iliac crest bone in single-level instrumented posterolateral fusion with comparable fusion rates and clinical outcomes. 1

• Synthetic calcium phosphate ceramics as graft extenders have been shown to be reasonable and safe for non-instrumented posterolateral fusion with equivalent fusion rates of 82-83% 1, 2
• β-tricalcium phosphate ceramic has demonstrated effectiveness as a graft extender for interbody fusion procedures 1, 2

rhBMP-2 as Bone Graft Substitute

Class I medical evidence supports the use of rhBMP-2 as a bone graft substitute in anterior lumbar interbody fusion involving a titanium cage, with fusion rates of 94.5% compared to 88.7% with autograft. 2

• Grade B evidence supports the use of rhBMP-2 as a bone graft extender when performing TLIF with structural interbody graft 1
• rhBMP-2 use is associated with decreased donor-site pain, shorter operating room times (24 minutes less), and slightly decreased blood loss (44 ml less) 2

Standard TLIF Technique Using Local Autograft

During minimally invasive transforaminal lumbar interbody fusion, autograft is routinely obtained locally during the laminectomy and facetectomy, which provides sufficient bone graft material when combined with allograft or bone graft substitutes. 3, 4

• The disc space and cage are packed with bone graft, which may involve local bone or bone substitutes depending on the specific clinical situation 4
• Fusion rates of 89-95% are achievable with local autograft combined with allograft or bone graft substitutes in instrumented single-level TLIF 1

Critical Pitfalls to Avoid

Do not confuse the medical necessity of the TLIF procedure itself (which IS medically necessary for appropriate indications like spondylolisthesis with stenosis) with the separate question of whether additional spinal bone autograft harvesting is necessary. 5, 6

• The laminectomy and facetectomy for arthrodesis are medically necessary components of the TLIF procedure 5
• However, the bone removed during these decompressive procedures provides adequate local autograft material 3, 4
• Additional separate autograft harvesting procedures add morbidity without improving fusion outcomes 1

Clinical Algorithm for Bone Graft Selection in TLIF

1. Use local autograft harvested during laminectomy/facetectomy as the primary graft material 1, 4
2. Supplement with allograft or bone graft substitutes (β-tricalcium phosphate) to achieve adequate graft volume 1, 2
3. Consider rhBMP-2 as an alternative if patient has risk factors for pseudarthrosis or if avoiding any autograft harvest is desired 2, 1
4. Reserve iliac crest bone graft only for revision cases or when local bone quality is severely compromised 3, 7

The bone marrow aspirate is also not medically necessary, as its effectiveness has not been established with low to moderate strength of evidence. 1