The procedure of anterior lumbar interbody fusion (ALIF) is commonly performed on patients suffering from pain and/or neurological symptoms associated with disorders of the lumbar spine caused by disc degeneration and trauma. Surgery is indicated when prolonged conservative management proves ineffective. Because an important objective of the ALIF procedure is solid arthrodesis of the degenerative spinal segment, bone graft selection is critical. Iliac crest bone grafts (ICBG) remain the “gold standard” for achieving lumbar fusion. However, patient dissatisfaction stemming from donor site morbidity, lengthier operating times and finite supply of ICBG has prompted a search for better alternatives. Here presented is a literature review evaluating available bone graft options assessed within the clinical setting. These options include autografts, allograft-based, synthetic and cell-based technologies. The emphasis is on the contentious use of recombinant human bone morphogenetic proteins, which is in widespread use and has demonstrated both significant osteogenic potential and risk of complications.
1NeuroSpineClinic, 2Spinal Injuries Unit, Prince of Wales Private Hospital, Randwick, and 3University of New South Wales, Sydney,New South Wales, Australia
The earliest report of anterior lumbar interbody fusion (ALIF) was in 1932 by Capener, who described its use in surgical management of spondylolisthesis1 Subsequent reports were byMercer for the treatment of disc pathology2and Burns in 19333. Its many advantages over posterior fusion, such as avoidance of paraspinal muscular injury, have resulted in increasing popularity of ALIF procedures. Although abundant clinical studies assessing bone graft alternatives for anterior cervical discectomy and fusion have been published4, grafting options for ALIF are not well documented in the literature. Successful arthrodesis depends on numerous surgical and host factors, including selection of a bone graft with elements critical for bone regeneration. Osteogenic properties of a graft enable it to provide stemcells and osteoblasts directly to regenerating bone, whereas osteoinductive factors such as bone morphogenetic proteins (BMPs) and other growth factors stimulate differentiation of progenitor cells into osteoblasts and osteocytes for new bone formation. An osteoconductive scaffold containing hydroxyapatite and collagen facilitates neovascularization that supports and maintains bone growth4–6. For fusions of the lumbar spine, autologous bone is the “gold standard” with which graft alternatives are compared because it encompasses these ideal properties, whilst also conferring minute risk of infection or host rejection and having excellent fusion rates. However, its disadvantages include donor site pain, blood loss, neurovascular injury, increased duration of hospital stay and limited availability7–9. To bypass these complications, many alternatives with potential for better patient outcomes are emerging (Table 1). Unfortunately, a lack of published clinical trials specifically assessing ALIF procedures limits the number of graft options accepted as safe alternatives to autografts. Also of note is that authors’ definitions of “successful fusion” vary, which can influence claimed study outcomes.
Allograft; Anterior lumbar interbody fusion; Autograft; Bone graft substitutes
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