Bone grafting

For patient information, click here

Overview
Bone grafting is a surgical procedure that replaces missing bone with material from the patient's own body, an artificial, synthetic, or natural substitute. Bone grafting is used to repair bone fractures that are extremely complex, pose a significant health risk to the patient, or fail to heal properly.

Autologous bone grafting
Autologous (or autogenous) bone grafting is the most desired. Autogenous bone grafting involves taking the patient's own bone from a part of the body where it is not essential (typically from the pelvis or iliac crest), and placing it where it's needed. Autogenous bone grafts are the most preferred by surgeons because there is less risk of the bone being rejected due to the fact that the bone originated in the patient's body, and therefore has the most abundant "amount of the patient's bone growing cells and proteins" and is a kind of "outline" for the new bone that is growing. One negative aspect of the procedure would be that the surgeon has to make more incisions than are required for the surgical site; he or she must make an extra incision to extract the bone that is being used for the surgery. An effect of this is "another location for postoperative pain" and it may increase the price of the procedure.

Autologous bone is typically harvested from intra-oral sources as the chin or extra-oral sources as the iliac crest, the fibula, the ribs, the mandible and even parts of the skull.

All bone requires a blood supply in the transplanted site. Depending on where the transplant site is and the size of the graft, an additional blood supply may be required. For these types of grafts, extraction of the part of the periosteum and accompanying blood vesels along with donor bone is required. This kind of graft is known as a free flap graft.

Allograft bone grafting
Allograft bone grafting is similar to the autogenous bone graft in that it is still harvested from people. Allograft bone in bone taken from cadavers or deceased people that have donated their bone so that it can be used for living people who are in need of it; it is typically sourced from a bone bank. The bone is disinfected and then frozen or lyophilized (freeze-dried). It helps minimize problems that come with taking the patient's bone and takes the place of a bone graft extender or replacement in the procedure. A disadvantage of this type of graft is that it is not very successful; it is fairly useful in several types of spinal fusions, but because it is not a very powerful "biological stimulant", it cannot, when used as the only grafting material, typically achieve a good fusion in procedures such as a lumbar spinal fusion.

Demineralized Bone Matrix
To demineralize bone, proteins that help with bone formation are taken from bones and are processed. Demineralized bone is suggested as only a bone graft extender because there really isn't much proof that it is "powerful enough" to fuse a human spine.

Synthetic variants
Artificial bone can be created from ceramics such as calcium phosphates (e.g. hydroxyapatite and tricalcium phosphate), Bioglass and calcium sulphate; all of which are biologically active to different degrees depending on solubility in the physiological environment (see: Hench 'Bioceramics: From Concept to Clinic' 1991, Journal of the American Ceramic Society). These materials can be doped with growth factors, ions such as strontium or mixed with bone marrow aspirate to increase biological activity. Some authors believe this method is inferior to autogenous bone grafting however infection and rejection of the graft is much less of a risk, the mechanical properties such as Young's modulus are comparable to bone. The presence of elements such as strontium can result in higher bone mineral density and enhanced osteoblast proliferation in vivo.

Xenografts
Xenograft bone substitute has its origin from a species other than human, such as bovine. Xenografts are usually only distributed as a calcified matrix.

Alloplastic Grafts
Alloplastic grafts may be made from hydroxylapatite, a naturally occurring mineral that is also the main mineral component of bone. They may be made from bioactive glass. Hydroxylapetite is a Synthetic Bone Graft, which is the most used now among other synthetic due to its osteoconduction, hareness and acceptability by bone there are also calcium carbonate which start to decrease in usage because it is completely resorbable in short time which make the bone easy to break again finally used is the tricalcium phosphate which now used in combination with hydroxylapatite thus give both effect osteoconduction and resorbsbility.

Growth Factors
Growth Factor enhanced grafts are produced using recombinant DNA technology. They consist of either Human Growth Factors or Morphogens (Bone Morphogenic Proteins in conjunction with a carrier medium, such as collagen).

Uses
The most common use of bone grafting is in the application of dental implants, in order to restore the edentulous area of a missing tooth. Dental implants require bones underneath them for support and to have the implant integrate properly into the mouth. People who have been edentulous (without teeth) for a prolonged period may not have enough bone left in the necessary locations. In this case, bone can be taken from the chin or from the pilot holes for the implants or even from the iliac crest of the pelvis and inserted into the mouth underneath the new implant.

In general, bone grafts are either used en block (such as from the chin or the ascending ramus area of the lower jaw) or particulated, in order to be able to adapt it better to a defect.

Another common bone graft, which is more substantial than those used for dental implants, is of the fibular shaft. After the segment of the fibular shaft has been removed normal activities such as running and jumping are permitted on the leg with the bone deficit. The grafted, vascularized fibulas have been used to restore skeletal integrity to long bones of limbs in which congenital bone defects exist and to replace segments of bone after trauma or malignant tumor invasion. The periosteum and nutrient artery are generally removed with the piece of bone so that the graft will remain alive and grow when transplanted into the new host site. Once the transplanted bone is secured into its new location it generally restores blood supply to the bone in which it has been attached.

Besides the main use of bone grafting--dental implants--this procedure is used to fuse joints to prevent movement, repair broken bones that have bone loss, and repair broken bone that has not yet healed.

Bone grafts are used in hopes that the defective bone will be healed or will regrow with little to no graft rejection.

Procedure
Depending on where the bone graft is needed, a different doctor may be requested to do the surgery. Doctors that do bone graft procedures are commonly orthopedic surgeons, otolaryngology head and neck surgeons, neurosurgeons, craniofacial surgeons, oral and maxillofacial surgeons, and periodontists.

Risks
As with any procedure, there are risks involved; among these include reactions to medicine and problems breathing, bleeding, and infection. Infection is reported to occur in less than 1% of cases and is curable with antibiotics. Overall, patients with a preexisting illness are at a higher risk of getting an infection as opposed to those who are overall healthy.

Risks for grafts from the iliac crest
Some of the potential risks and complications of bone grafts employing the iliac crest as a donor site include :


 * acquired bowel herniation (this becomes a risk for larger donor sites (>4 cm)) . About 20 cases have been reported in the literature from 1945 till 1989 and only a few hundred cases have been reported worldwide
 * meralgia paresthetica (injury to the lateral femoral cutaneous nerve also called Bernhardt-Roth's syndrome)
 * pelvic instability
 * fracture (extremely rare and usually with other factors )
 * injury to the clunial nerves (this will cause posterior pelvic pain which is worsened by sitting)
 * injury to the ilioinguinal nerve
 * infection
 * minor hematoma (a common occurrence)
 * deep hematoma requiring surgical intervention
 * seroma
 * ureteral injury
 * pseudoaneurysm of iliac artery (rare)
 * tumor transplantation
 * cosmetic defects (chiefly caused by not preserving the superior pelvic brim)
 * chronic pain

Bone grafts harvested from the posterior iliac crest in general have less morbidity, but depending on the type of surgery, may require a flip while the patient is under general anesthesia.

Recovery and Aftercare
The amount of time it takes for an individual to recovery depends on the severity of the injury being treated and lasts anywhere from 2 weeks to 2 months with a possibility of vigorous exercise being barred for up to 6 months.

Costs
Bone graft procedures consist of more than just the surgery. The average cost of bone graft procedures ranges from approximately $33,860 to $37,227. Besides the cost of the bone graft itself (ranging from $250 to $900) other expenses for the procedure include: surgeon's fees (these vary), anesthesiologist fees (approximately $350 to $400 per hour), hospital charges (these vary; averaging about $1,500 to $1,800 a day), medication charges ($200 to $400), and additional fees for services such as medical supplies, diagnostic procedures, equipment use fees, etc.