I know it’s been over a month since I posted a new blog but I had to write something about an article I just read in one of my Orthopedic journals talking about the trends of bone graft and what we can expect in the future.
Let’s face it, as medicine continues to conduct research and we find out more and more about the human body and it’s properties, there’s a fascination for trying to mimic or imitate what Mother Nature has given us.
Take for instance in our discussion of bone and bone properties. Bone is very dynamic – meaning constantly building and constantly breaking down. In simple terms, the rate and quality of bone being deposited is largely effected by a number of different factors – these include nutrition status, baseline bone integrity, co-morbid conditions or more simply – underlying medical issues, just to name a few. All of these variables are put together and this in turn determines how your bone scaffolding will be put down during a fracture, broken bone, or iatrogenic trauma.
There are 3 main types of bone graft. The first and gold standard (always will be the gold standard) is Autograft Bone – “Auto – meaning your own” bone. There are multiple different areas to get your own bone from including your pelvis(iliac crest), leg (proximal tibia) and other areas too like your rib or your spine.
AUTOGRAFT = AUTOLOGOUS = AUTOGENOUS BONE
“THE GOLD STANDARD”
Autograft can be taken from a number of different areas called “Harvesting” and can be transferred from the same area of the body to another part of the body. This graft contains your own body’s proteins, antibodies, and other properties that help to minimize the risk of rejection and can provide a solid ridge of bone especially in spine fusions.
Advantages to Autograft:
It contains osteophytes or bone-growing cells and proteins to help develop new bone growth.
It provides a calcium scaffolding or matrix for new bone growth to grow on.
There is a greater chance for Spinal Fusion Success versus other substitutes
Minimizes disease transmission and rejection
Disadvantages to Autograft:
There are few risks associated with autograft and although they are rare, it is worth mentioning that they can sometimes occur. Mainly, surgical wound problems like infection and depending on the site of harvesting, nerve injury, and sometimes excessive bleeding from the site.
One complaint that I occasionally hear of is about pain at the bone graft harvest site. This is a subjective measurement of course and there are a certain number of surgical techniques that can used to minimize the amount of pain at the donor site. It has been estimated that up to 25% of patients will experience temporary discomfort at these sites although the actual number is likely a lot less than that.
Allograft (Cadaver) Bone Graft
Allograft is bone tissue that has been harvested from a cadaver. This is usually done by very strict regulations and monitoring to ensure the potential risk of disease transmission and in my opinion, lower fusion rates.
It should be noted that allograft bone does provide the calcium scaffolding needed for bone ingrowth but it lacks the bone-producing proteins and growth cells required for new bone growth stimulation.
This in turn theoretically leads to a lower chance of fusion compared to autograft but there are some studies that suggest that it is comparable to the gold standard of autograft.
Bone Growth Substitutes or Commercial Products
This has been an area in spine surgery that is what we call a “hot topic” but it often leads to many unwanted side effects that do not work in favor of spinal fusion like we would hope. I will admit that there are some times where there it can be advantageous for a surgeon to use these substitutes but in my opinion, nothing is better than your own bone.
As you can tell, I am not a big fan of this category and often like to call this category “Silly Putty” as it is often made of synthetic or naturally-occuring products that have been manipulated to help mimic natural bone. These agents are usually very expensive and often imitate to a certain degree our own bone.
There are 3 main types or variations to these substitutes and they are:
Demineralized Bone Matrix (DBM)
Synthetic bone graft extenders
Bone Morphogenetic Proteins (BMP)
I only mention these substitutes to let you know that there are alternatives to autograft and allograft bone. I will not spend much time here on their discussion because these various agents can be discussed for hours sometimes days with often minimal advantages.
For more information, please feel free to send me a comment so that I can further provide you with the information you need.