Bone grafting

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Bone grafting_table_infobox_0

Bone graftingBone grafting_header_cell_0_0_0
ICD-9-CMBone grafting_header_cell_0_1_0 Bone grafting_cell_0_1_1
MeSHBone grafting_header_cell_0_2_0 Bone grafting_cell_0_2_1
MedlinePlusBone grafting_header_cell_0_3_0 Bone grafting_cell_0_3_1

Bone grafting is a surgical procedure that replaces missing bone in order to repair bone fractures that are extremely complex, pose a significant health risk to the patient, or fail to heal properly. Bone grafting_sentence_0

Some small or acute fractures can be cured without bone grafting, but the risk is greater for large fractures like compound fractures. Bone grafting_sentence_1

Bone generally has the ability to regenerate completely but requires a very small fracture space or some sort of scaffold to do so. Bone grafting_sentence_2

Bone grafts may be autologous (bone harvested from the patient’s own body, often from the iliac crest), allograft (cadaveric bone usually obtained from a bone bank), or synthetic (often made of hydroxyapatite or other naturally occurring and biocompatible substances) with similar mechanical properties to bone. Bone grafting_sentence_3

Most bone grafts are expected to be reabsorbed and replaced as the natural bone heals over a few months’ time. Bone grafting_sentence_4

The principles involved in successful bone grafts include osteoconduction (guiding the reparative growth of the natural bone), osteoinduction (encouraging undifferentiated cells to become active osteoblasts), and osteogenesis (living bone cells in the graft material contribute to bone remodeling). Bone grafting_sentence_5

Osteogenesis only occurs with autograft tissue and allograft cellular bone matrices. Bone grafting_sentence_6

Biological mechanism Bone grafting_section_0

Bone grafting is possible because bone tissue, unlike most other tissues, has the ability to regenerate completely if provided the space into which to grow. Bone grafting_sentence_7

As native bone grows, it will generally replace the graft material completely, resulting in a fully integrated region of new bone. Bone grafting_sentence_8

The biologic mechanisms that provide a rationale for bone grafting are osteoconduction, osteoinduction and osteogenesis. Bone grafting_sentence_9

Osteoconduction Bone grafting_section_1

Osteoconduction occurs when the bone graft material serves as a scaffold for new bone growth that is perpetuated by the native bone. Bone grafting_sentence_10

Osteoblasts from the margin of the defect that is being grafted utilize the bone graft material as a framework upon which to spread and generate new bone. Bone grafting_sentence_11

In the very least, a bone graft material should be osteoconductive. Bone grafting_sentence_12

Osteoinduction Bone grafting_section_2

Osteoinduction involves the stimulation of osteoprogenitor cells to differentiate into osteoblasts that then begin new bone formation. Bone grafting_sentence_13

The most widely studied type of osteoinductive cell mediators are bone morphogenetic proteins (BMPs). Bone grafting_sentence_14

A bone graft material that is osteoconductive and osteoinductive will not only serve as a scaffold for currently existing osteoblasts but will also trigger the formation of new osteoblasts, theoretically promoting faster integration of the graft. Bone grafting_sentence_15

Osteopromotion Bone grafting_section_3

Osteopromotion involves the enhancement of osteoinduction without the possession of osteoinductive properties. Bone grafting_sentence_16

For example, enamel matrix derivative has been shown to enhance the osteoinductive effect of demineralized freeze dried bone allograft (DFDBA), but will not stimulate new bone growth alone. Bone grafting_sentence_17

Osteogenesis Bone grafting_section_4

Osteogenesis occurs when vital osteoblasts originating from the bone graft material contribute to new bone growth along with bone growth generated via the other two mechanisms. Bone grafting_sentence_18

Method Bone grafting_section_5

Depending on where the bone graft is needed, a different doctor may be requested to do the surgery. Bone grafting_sentence_19

Doctors that do bone graft procedures are commonly orthopedic surgeons, otolaryngology head and neck surgeon, neurosurgeons, craniofacial surgeons, oral and maxillofacial surgeons, podiatric surgeons and periodontists, dental surgeons, oral surgeons and implantologists. Bone grafting_sentence_20

Autograft Bone grafting_section_6

Autologous (or autogenous) bone grafting involves utilizing bone obtained from the same individual receiving the graft. Bone grafting_sentence_21

Bone can be harvested from non-essential bones, such as from the iliac crest, or more commonly in oral and maxillofacial surgery, from the mandibular symphysis (chin area) or anterior mandibular ramus (the coronoid process); this is particularly true for block grafts, in which a small block of bone is placed whole in the area being grafted. Bone grafting_sentence_22

When a block graft will be performed, autogenous bone is the most preferred because there is less risk of the graft rejection because the graft originated from the patient's own body. Bone grafting_sentence_23

As indicated in the chart above, such a graft would be osteoinductive and osteogenic, as well as osteoconductive. Bone grafting_sentence_24

A negative aspect of autologous grafts is that an additional surgical site is required, in effect adding another potential location for post-operative pain and complications. Bone grafting_sentence_25

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. Bone grafting_sentence_26

All bone requires a blood supply in the transplanted site. Bone grafting_sentence_27

Depending on where the transplant site is and the size of the graft, an additional blood supply may be required. Bone grafting_sentence_28

For these types of grafts, extraction of the part of the periosteum and accompanying blood vessels along with donor bone is required. Bone grafting_sentence_29

This kind of graft is known as a vital bone graft. Bone grafting_sentence_30

An autograft may also be performed without a solid bony structure, for example using bone reamed from the anterior superior iliac spine. Bone grafting_sentence_31

In this case, there is an osteoinductive and osteogenic action, however there is no osteoconductive action, as there is no solid bony structure. Bone grafting_sentence_32

Chin offers a large amount of cortico-cancellous autograft and easy access among all the intraoral sites. Bone grafting_sentence_33

It can be easily harvested in the office settings under local anaesthesia on an outpatient basis. Bone grafting_sentence_34

Proximity of the donor and recipient sites reduce operative time and cost. Bone grafting_sentence_35

Convenient surgical access, low morbidity, elimination of hospital stay, minimal donor site discomfort and avoidance of cutaneous scars are the added advantages. Bone grafting_sentence_36

Dentin graft Bone grafting_section_7

Dentin bone, made from extracted teeth, Dentin comprises more than 85% of tooth structure, the enamel consists of HA mineral and comprises 10% of tooth structure. Bone grafting_sentence_37

Dentin is similar to bone in its chemical composition, by volume 70-75% is HA mineral and 20% organic matrix, mostly fibrous type I collagen. Bone grafting_sentence_38

Dentin, like bone, may release growth and differentiating factors while being resorbed by osteoclasts. Bone grafting_sentence_39

In order to make the dentin graft usable and bacteria-free some companies have developed clinical procedures which include grinding, sorting and cleaning of the teeth for immediate or future use. Bone grafting_sentence_40

In Korea, the Korea Tooth Bank performed bio-recycling of 38 000 patients' own teeth from January 2009 until October 2012. Bone grafting_sentence_41

Allografts Bone grafting_section_8

Allograft bone, like autogenous bone, is derived from humans; the difference is that allograft is harvested from an individual other than the one receiving the graft. Bone grafting_sentence_42

Allograft bone can be taken from cadavers 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. Bone grafting_sentence_43

Bone banks also supply allograft bone sourced from living human bone donors (usually hospital inpatients) who are undergoing elective total hip arthroplasty (total hip replacement surgery). Bone grafting_sentence_44

During total hip replacement, the orthopaedic surgeon removes the patient's femoral head, as a necessary part of the process of inserting the artificial hip prosthesis. Bone grafting_sentence_45

The femoral head is a roughly spherical area of bone, located at the proximal end of the femur, with a diameter of 45 mm to 56 mm in adult humans. Bone grafting_sentence_46

The patient's femoral head is most frequently discarded to hospital waste at the end of the surgical procedure. Bone grafting_sentence_47

However, if a patient satisfies a number of stringent regulatory, medical and social history criteria, and provides informed consent, their femoral head may be deposited in the hospital's bone bank. Bone grafting_sentence_48

There are three types of bone allograft available: Bone grafting_sentence_49

Bone grafting_ordered_list_0

  1. Fresh or fresh-frozen boneBone grafting_item_0_0
  2. Freeze-dried bone allograft (FDBA)Bone grafting_item_0_1
  3. Demineralized freeze-dried bone allograft (DFDBA)Bone grafting_item_0_2

Alloplastic grafts Bone grafting_section_9

Alloplastic grafts may be made from hydroxyapatite, a naturally occurring mineral that is also the main mineral component of bone. Bone grafting_sentence_50

They may be made from bioactive glass. Bone grafting_sentence_51

Hydroxylapatite is a Synthetic Bone Graft, which is the most used now among other synthetic due to its osteoconduction, hardness and acceptability by bone. Bone grafting_sentence_52

Tricalcium phosphate which now used in combination with hydroxylapatite thus give both effect osteoconduction and resorbability. Bone grafting_sentence_53

Polymers such as some microporous grades of PMMA and various other acrylates (such as polyhydroxylethylmethacrylate aka PHEMA), coated with calcium hydroxide for adhesion, are also used as alloplastic grafts for their inhibition of infection and their mechanical resilience and biocompatibility. Bone grafting_sentence_54

Calcifying marine algae such as Corallina officinalis have a fluorohydroxyapatitic composition whose structure is similar to human bone and offers gradual resorption, thus it is treated and standardized as "FHA (Fluoro-hydroxy-apatitic) biomaterial" alloplastic bone grafts. Bone grafting_sentence_55

Synthetic variants Bone grafting_section_10

Artificial bone can be created from ceramics such as calcium phosphates (e.g. hydroxyapatite and tricalcium phosphate), Bioglass and calcium sulfate; all of which are biologically active to different degrees depending on solubility in the physiological environment. Bone grafting_sentence_56

These materials can be doped with growth factors, ions such as strontium or mixed with bone marrow aspirate to increase biological activity. Bone grafting_sentence_57

Some authors believe this method is inferior to autogenous bone grafting however infection and rejection of the graft is much less of a risk, and the mechanical properties such as Young's modulus are comparable to bone. Bone grafting_sentence_58

The presence of elements such as strontium can result in higher bone mineral density and enhanced osteoblast proliferation in vivo. Bone grafting_sentence_59

Temporary spacer Bone grafting_section_11

A synthetic material may be used as a temporary antibiotic spacer before being replaced by a more permanent material. Bone grafting_sentence_60

For example, the Masquelet procedure consists of initially using PMMA mixed with an antibiotic (vancomycin or gentamicin) for 4–12 weeks, and then replacing the space with an autologous bone graft. Bone grafting_sentence_61

It can be used to treat posttraumatic bone defects. Bone grafting_sentence_62

Xenografts Bone grafting_section_12

Xenograft bone substitute has its origin from a species other than human, such as bovine bone (or recently porcine bone) which can be freeze dried or demineralized and deproteinized. Bone grafting_sentence_63

Xenografts are usually only distributed as a calcified matrix. Bone grafting_sentence_64

Madrepore and or millepore type of corals are harvested and treated to become 'coral derived granules' (CDG) and other types of coralline xenografts. Bone grafting_sentence_65

Coral based xenografts are mainly calcium carbonate (and an important proportion of fluorides, useful in the context of grafting to promote bone development) while natural human bone is made of hydroxyapatite along with calcium phosphate and carbonate: the coral material is thus either transformed industrially into hydroxyapatite through a hydrothermal process, yielding a non-resorbable xenograft, or simply the process is omitted and the coralline material remains in its calcium carbonate state for better resorption of the graft by the natural bone. Bone grafting_sentence_66

The coral xenograft is then saturated with growth enhancing gels and solutions. Bone grafting_sentence_67

Growth Factors Bone grafting_section_13

Growth Factor enhanced grafts are produced using recombinant DNA technology. Bone grafting_sentence_68

They consist of either Human Growth Factors or Morphogens (Bone Morphogenic Proteins in conjunction with a carrier medium, such as collagen). Bone grafting_sentence_69

Recovery and aftercare Bone grafting_section_14

The time it takes for an individual to recover depends on the severity of the injury being treated and lasts anywhere from two weeks to two months, with a possibility of vigorous exercise being barred for up to six months. Bone grafting_sentence_70

Distal femoral bone graft takes up-to 6 months to heal. Bone grafting_sentence_71

Uses Bone grafting_section_15

Dental implants Bone grafting_section_16

The most common use of bone grafting is in the application of dental implants to restore the edentulous area of a missing tooth. Bone grafting_sentence_72

Dental implants require bones underneath them for support and proper integration into the mouth. Bone grafting_sentence_73

As mentioned earlier bone grafts come in various forms such as autologous (from the same person), Allograft, Xenograft (mainly bovine bone), and Alloplastic materials. Bone grafting_sentence_74

Bone grafts can be used prior to implant placement or simultaneously. Bone grafting_sentence_75

People who have been edentulous (without teeth) for a prolonged period may not have enough bone left in the necessary locations. Bone grafting_sentence_76

In this case, autologous bone can be taken from the chin, 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. Bone grafting_sentence_77

Alternatively, exogenous bone can be used: xenograft is the most commonly used, because it offers the advantage of exceptional volume stability over time. Bone grafting_sentence_78

Allograft offers the best regeneration quality but has lower volume stability. Bone grafting_sentence_79

Often a mix of different kinds of bone grafts is used. Bone grafting_sentence_80

In general, bone graft is either used en bloc (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. Bone grafting_sentence_81

Dental bone grafting is a specialized oral surgical procedure that has been developed to reestablish lost jawbone. Bone grafting_sentence_82

This loss can be a result of dental infection of abscess, periodontal disease, trauma, or the natural process of aging. Bone grafting_sentence_83

There are various reasons for replacing lost bone tissue and encouraging natural bone growth, and each technique tackles jawbone defects differently. Bone grafting_sentence_84

Reasons that bone grafting might be needed include sinus augmentation, socket preservation, ridge augmentation, or regeneration. Bone grafting_sentence_85

Fibular shaft Bone grafting_section_17

Another common bone graft, which is more substantial than those used for dental implants, is of the fibular shaft. Bone grafting_sentence_86

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. Bone grafting_sentence_87

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. Bone grafting_sentence_88

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. Bone grafting_sentence_89

Once the transplanted bone is secured into its new location it generally restores blood supply to the bone in which it has been attached. Bone grafting_sentence_90

Other Bone grafting_section_18

Bone grafts are used in hopes that the defective bone will be healed or will regrow with little to no graft rejection. Bone grafting_sentence_91

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 grafting_sentence_92

Furthermore, bone grafts or substitutes are widely used for augmentation of spinal fusion procedures. Bone grafting_sentence_93

Risks Bone grafting_section_19

As with any procedure, there are risks involved; these include reactions to medicine, problems breathing, bleeding, and infection. Bone grafting_sentence_94

Infection is reported to occur in less than 1% of cases and is curable with antibiotics. Bone grafting_sentence_95

Overall, patients with a preexisting illness are at a higher risk of getting an infection as opposed to those who are overall healthy. Bone grafting_sentence_96

Risks for grafts from the iliac crest Bone grafting_section_20

Some of the potential risks and complications of bone grafts employing the iliac crest as a donor site include: Bone grafting_sentence_97

Bone grafting_unordered_list_1

  • 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 worldwideBone grafting_item_1_3
  • meralgia paresthetica (injury to the lateral femoral cutaneous nerve also called Bernhardt-Roth's syndrome)Bone grafting_item_1_4
  • pelvic instabilityBone grafting_item_1_5
  • fracture (extremely rare and usually with other factors)Bone grafting_item_1_6
  • injury to the clunial nerves (this will cause posterior pelvic pain which is worsened by sitting)Bone grafting_item_1_7
  • injury to the ilioinguinal nerveBone grafting_item_1_8
  • infectionBone grafting_item_1_9
  • minor hematoma (a common occurrence)Bone grafting_item_1_10
  • deep hematoma requiring surgical interventionBone grafting_item_1_11
  • seromaBone grafting_item_1_12
  • ureteral injuryBone grafting_item_1_13
  • pseudoaneurysm of iliac artery (rare)Bone grafting_item_1_14
  • tumor transplantationBone grafting_item_1_15
  • cosmetic defects (chiefly caused by not preserving the superior pelvic brim)Bone grafting_item_1_16
  • chronic painBone grafting_item_1_17

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. Bone grafting_sentence_98

Costs Bone grafting_section_21

Bone graft procedures consist of more than just the surgery itself. Bone grafting_sentence_99

The complete 3-month total cost of a complex posterolateral lumbar spine fusion bone graft supplemented with graft extenders ranges from a mean of approximately US$33,860 to US$37,227. Bone grafting_sentence_100

This price includes all visits in and out of the hospital for 3 months. Bone grafting_sentence_101

Besides the cost of the bone graft itself (ranging from US$250 to US$900) other expenses for the procedure include: outpatient rehabilitation fees (US$5,000 to US$7,000), screws and rods (US$7,500), room and board (US$5,000), operating room (US$3,500), sterile supplies (US$1,100), physical therapy (US$1,000), surgeon's fees (average US$3,500), anesthesiologist fees (approximately US$350 to US$400 per hour), medication charges (US$1,000), and additional fees for services such as medical supplies, diagnostic procedures, equipment use fees, etc. Bone grafting_sentence_102

See also Bone grafting_section_22

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: grafting.