A spine fusion is a slow biological process that requires the body to create a new bony bridge between many bones that used to move independently of each other. This usually requires some sort of bone graft to bridge the gaps where the new bone needs to form in order for the fusion to occur. There are many sources of bone for bone grafts, and most forms of scoliosis surgery utilize some form of autogenous bone graft, which is taken from a different part of the patient who is being operated upon. When this is done during spinal fusion surgery, the bone often comes from the patient's spine, ribs, or pelvis.
The segment of the spine that is going to be fused is often prepared in such a way that the cancellous, or bone marrow parts of the bone are exposed. Chips of bone can be removed from certain parts of the spine and then packed in the areas where the fusion is going to occur. This is called local bone grafting.
Another source of bone for bone grafting, commonly used in the past, is the ribs. Many times, a rib may need to be removed in order to allow the surgeon to have access to a certain part of the spine - most commonly the front of the spine. This rib can then be shaped into many small pieces that are packed in the area of the spine where the fusion will occur. Bone graft is also available from the ribs that are removed during a thoracoplasty. A thoracoplasty is performed in order to reduce the rib hump that often occurs in scoliosis patients as their spine rotates to one side, which causes their ribs to stick out more prominently on one side. This procedure removes a part of the rib at the top of the rib hump so that the hump is much less noticeable after surgery.
A more common source of bone for bone graft comes from the patient's own pelvis. The iliac crest, which can be felt just above the front of the hips at the waistline, is an excellent source of extra bone that can be used to help the spine to fuse. Where bone graft comes from does have some significant consequences for the patient. The best quality bone comes from the patient who is being operated upon, but there is only a limited amount of autogenous bone available, and harvesting bone from certain places can cause problems later on. For instance, if bone is harvested from the iliac crest, the patient can experience pain, numbness, and persistent discomfort in this area after surgery. Removing bone for bone graft also increases the amount of time required for the surgery, the amount of blood that is lost during surgery, and sometimes requires a separate incision to be made in the skin.
In order to avoid the downside of taking bone from other parts of the patient, several alternate sources of bone graft have been developed. Allograft bone is more commonly know as "bone-bank bone" or "donor bone" and can be used during spinal fusion. Donor bone is utilized in many situations, such as in patients who have had previous surgeries where bone has already been taken in order to perform a fusion. Bone-bank bone is collected from donors who have agreed to donate their organs for transplant purposes after they have died - much like the process of heart or kidney donation. Bone-bank bone is extensively tested and processed in order to make sure that it is safe to use in patients.
What type of bone graft is used in each spine surgery depends upon a combination of factors, including the preference of the surgeon, the preference of the patient, how much bone is needed, and what alternative sources of bone graft are available. It is a good idea to discuss this issue with your surgeon if you are in the process of preparing for spine surgery.
It is important to discuss the potential risks, complications, and benefits of spinal surgery with your doctor prior to receiving treatment, and that you rely on your physician's judgment. Only your doctor can determine whether you are a suitable candidate for this treatment.
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