Journal of neurosurgery. Spine
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Interbody fusion techniques have been promoted as an adjunct to lumbar fusion procedures in an effort to enhance fusion rates and potentially improve clinical outcome. The medical evidence continues to suggest that interbody techniques are associated with higher fusion rates compared with posterolateral lumbar fusion (PLF) in patients with degenerative spondylolisthesis who demonstrate preoperative instability. There is no conclusive evidence demonstrating improved clinical or radiographic outcomes based on the different interbody fusion techniques. ⋯ No substantial clinical benefit has been demonstrated when a PLF is included with an interbody fusion. For lumbar degenerative disc disease without instability, there is moderate evidence that the standalone anterior lumbar interbody fusion (ALIF) has better clinical outcomes than the ALIF plus instrumented, open PLF. With regard to type of interbody spacer used, frozen allograft is associated with lower pseudarthrosis rates compared with freeze-dried allograft; however, this was not associated with a difference in clinical outcome.
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In an attempt to enhance the potential to achieve a solid arthrodesis and avoid the morbidity of harvesting autologous iliac crest bone (AICB) for a lumbar fusion, numerous alternatives have been investigated. The use of these fusion adjuncts has become routine despite a lack of convincing evidence demonstrating a benefit to justify added costs or potential harm. Potential alternatives to AICB include locally harvested autograft, calcium-phosphate salts, demineralized bone matrix (DBM), and the family of bone morphogenetic proteins (BMPs). ⋯ The use of recombinant human BMP-2 (rhBMP-2) as a substitute for AICB, when performing an interbody lumbar fusion, is considered an option since similar outcomes have been observed; however, the potential for heterotopic bone formation is a concern. The use of rhBMP-2, when combined with calcium phosphates, as a substitute for AICB, or as an extender, when used with local autograft or AICB, is also considered an option as similar fusion rates and clinical outcomes have been observed. Surgeons electing to use BMPs should be aware of a growing body of literature demonstrating unique complications associated with the use of BMPs.