Bone Grafting Techniques & Products

In a spinal fusion, the goal is for two or more vertebrae to grow together into one solid piece of bone. The screws and rods only hold everything still while that happens — it is the bone graft placed between the bones that provides the biology for new bone to bridge the gap. There are several different graft materials, each with different properties and a different evidence base, and they are often combined. To judge any of them it helps to know the three ingredients a fusion needs: osteogenic cells that form bone, an osteoconductive scaffold for new bone to grow along, and osteoinductive signals that stimulate bone formation. Different materials supply these in different combinations, and that is the whole story of graft choice.

• People undergoing a spinal fusion for instability, deformity, or other conditions requiring vertebrae to be joined
• The choice of graft is individualised to the person, the number of levels, and any factors affecting healing (such as smoking or osteoporosis)

• Your own bone (autograft), taken locally from the operation or occasionally from the pelvis (iliac crest), remains the gold standard because it supplies all three ingredients at once — cells, scaffold and signal. Donor bone (allograft) provides an osteoconductive scaffold and some signal, and is rigorously screened so disease transmission is extremely rare. A processed form of allograft, demineralised bone matrix (DBM), is acid-treated to expose its natural bone-forming proteins; it comes as putty, gel, granules or strips, and in comparative studies of instrumented lumbar fusion has achieved fusion rates and outcomes comparable to far more expensive products. Synthetic ceramics — beta-tricalcium phosphate (beta-TCP) and hydroxyapatite — are scaffolds the body gradually replaces with its own bone, and are often combined with bone marrow aspirate (which adds cells); beta-TCP with marrow aspirate has shown results comparable to iliac crest autograft. Bioactive glass (bioglass) is a specially engineered glass that, as it dissolves, releases ions that actively switch on bone-forming genes — a property called osteostimulation — and the evidence supports its safety and effectiveness as an autograft extender in cervical and lumbar fusion. And recombinant human bone morphogenetic protein-2 (rhBMP-2, sold as INFUSE on a collagen sponge) is a potent osteoinductive signal that produces high fusion rates, but is used selectively because of recognised complications and higher cost. Mr Madi selects and often combines these materials to give the best chance of a solid fusion for the individual.

• Provides the biology needed for two vertebrae to fuse into solid bone
• A range of evidence-based options allows the graft to be tailored to the person, the levels, and their healing
• Autograft (your own local bone) supplies all three ingredients and avoids a separate donor site
• Demineralised bone matrix (DBM) offers outcomes comparable to far costlier products as a graft extender
• Ceramics (beta-TCP, hydroxyapatite), often with bone marrow aspirate, give a scaffold that becomes your own bone
• Bioactive glass (bioglass) actively stimulates bone formation (osteostimulation) and extends a small amount of autograft
• rhBMP-2 provides powerful bone-forming signalling for selected, difficult cases

• No graft guarantees fusion; sometimes the bones fail to knit (non-union / pseudarthrosis), which may need further treatment
• Harvesting bone from the pelvis, when needed, can cause pain at that site
• Donor bone and demineralised bone matrix are very carefully screened, making disease transmission extremely rare
• rhBMP-2 is used selectively: it is associated with specific complications (nerve-related swelling and inflammation, heterotopic ossification, neck swelling in cervical use) and higher cost, and overall its fusion success is broadly comparable to autograft
• Smoking, poor bone quality and some medications reduce fusion success and are best addressed before surgery

• Different graft choices — autograft, allograft, synthetic ceramics, or biologics — selected to suit the case
• Non-fusion surgical options where appropriate for the underlying problem
• Optimising bone health and stopping smoking to improve fusion chances

The graft works quietly in the background over weeks and months as new bone forms and the fusion becomes solid; this is why activity is built up gradually and why bone health matters so much to the outcome. The graft choice does not change the early recovery from the operation itself, but it is central to the long-term success of the fusion. Your surgeon will explain which materials are planned for you and why.

• —British Association of Spine Surgeons (BASS)
• —NICE — Relevant interventional procedures guidance
• —National Osteoporosis Guideline Group (NOGG) — Clinical Guideline

This information is for general patient education and is not a substitute for an individual consultation. Always seek personalised advice from a qualified spinal specialist.