Autogenous Grafts Medical Assignment Help

Autogenous Grafts

Also known as autogratts or self-grafts, autogenous grafts are composed of tissues from the same individual. Fresh autogenous bone is the most ideal’ bone graft material. It . is unique among bone grafts- in that it is the only type of bone graft to supply living, immunocompatible bone cells essential to phase I osteogenesis. The larger number of living cells that are transplanted, the more osseous tissue that will be produced.  Autogenous bone is the type used most frequently in oral and maxillofacial surgery. It can be obtained from a
host of sites in the body and can be taken in several forms. Block grafts are solid’ pieces of both cortical bone and underlying cancellous bone (Fig. 28-1). The iliac crest is  often used as a source for this type of graft. The entire thick-
uneness of the ilium can be obtained, or the ilium can be split to obtain a thinner piece of block graft. Ribs also constitute

FIG. 28-1 The use of autoqenous block corucoc ancellous-bone graft to replace defect in mandibular symphysis. This patient had an ameloblastoma of the anterior mandible. A, Computed tomography (CT) scan showing expansion and irregularity of bone. B, Specimen that was resected using an intraoral approach. C, Bone fJ:ate used to span the resection gap, controlling the position of the right and left mandibular halves and allowing the patient to function postoperatively without th~ need for maxillomandibular fixation. D, Panoramic radiograph taken immediately after resection. Three months later the oral soft tissues have healed and the patient IS prepared for bone graft reconstruction of the symphysis.

FIG. 28-1 The use of autoqenous block corucoc ancellous-bone graft to replace defect in mandibular
symphysis. This patient had an ameloblastoma of the anterior mandible. A, Computed tomography
(CT) scan showing expansion and irregularity of bone. B, Specimen that was resected using an intraoral
approach. C, Bone fJ:ate used to span the resection gap, controlling the position of the right and left
mandibular halves and allowing the patient to function postoperatively without th~ need for maxillomandibular
fixation. D, Panoramic radiograph taken immediately after resection. Three months later the
oral soft tissues have healed and the patient IS prepared for bone graft reconstruction of the symphysis.

FIG. 28-1-':" contd E, Surgical exposure using an extraoral approach. F, Full-thickness bone graft harvested from the ilium along with particulate marrow and cancellous bone to use as "filler" and to provide osteocornpetent cells. G, Bone graft attached to the bone plate. Particulate bone is then packed around the area to promote bone healing. H, Panoramic radiograph taken 6 months later showing bone fill and healing of graft to both mandibular halvesFIG. 28-1-':" contd E, Surgical exposure using an extraoral approach. F, Full-thickness bone graft harvested from the ilium along with particulate marrow and cancellous bone to use as "filler" and to provide osteocornpetent cells. G, Bone graft attached to the bone plate. Particulate bone is then packed around the area to promote bone healing. H, Panoramic radiograph taken 6 months later showing bone fill and healing of graft to both mandibular halves

FIG. 28-1-‘:” contd E, Surgical exposure using an extraoral approach. F, Full-thickness bone graft
harvested from the ilium along with particulate marrow and cancellous bone to use as “filler” and to
provide osteocornpetent cells. G, Bone graft attached to the bone plate. Particulate bone is then
packed around the area to promote bone healing. H, Panoramic radiograph taken 6 months later
showing bone fill and healing of graft to both mandibular halves

a form 01 block graft. Particulate marrow and cancellousbone  grafts are obtained by harvesting the medullary boneand the associated endosteum and hematopoietic marrow. . Particulate marrow and cancellous-bone grafts produce the greatest concentration of osteogenic cells, and, because of the particulate nature, more cells survive transplantation because of the access they have to nutrients in the surrounding graft bed. The most common site for.the procurement of thfs type of graft is the ilium. The iliac crest can be entered, and large volumes of particulate marrow and cancellous- bone grafts can be obtained with large curettes. The diploic space of the cranial vault has recently been used as a site for obtaining this type of graft when small amounts of bone chips are needed (e.g., alveolar cleft grafts). Autogenous bone may also be transplanted while maintainlng
the blood supply to the graft, Two methods can accbmplish this: The first involves the transfer of a bone graft pedicled to a muscular (or muscular and skin) pedicle. The bone is not stripped of its soft tissue pedicle, preserving some blood supply to the bone graft. Thus the amount
‘of surviving osteogenic cells is potentially great. An example of this type of autogenous graft is asegrnent of the clavicle transferred to the mandible, pedicled to the sternocleidomastoid muscle. The second method by which autogenous bone can be transplanted without losing blood , supply is by the use of microsurgical techniques. Ablock of ilium, tibia, rib, or other suitable .bone is.removed along with the overlying soft tissues after dissecting free an artery and a vein that supply the tissue. An artery and a vein are also prepared in the recipient bed. Once the bone graftis secured in place, the artery and veins are reconnected using microvascular anastomoses. In this way the blood supply to the bone graft is restored. Both of these types of autogenous grafts are known as composite grafts, because they contain both soft tissue and osseous elements. The first type described, in which the
bone maintains a m uscular origin, is a pedicled composite graft. The pedicle is the soft tissue remaining on it, which supplies the vasculature. The second type of composite graft is a free composite .graft, meaning that it is totally removed from the body and immediately replaced, and its
blood supply is restored by reconnection of blood vessels. Although these types of grafts may seem ideal, they have some shortcomings when used to restore defects of the jaws. Because the soft tissues attached to the bone
graft maintain the blood supply, there can be minimal stripping of the soft tissue from the graft during procurement and placement. Thus the size and shape of the graft cannot be altered to any significant degree. Frequently,
inadequate bulk of bone is provided when these grafts are used to restore mandibular continuity defects. Another problem is the morbidity to the donor site. Instead of just removing osseous tissue, soft tissues are also’ removed with composite grafts, which causes greater functional  and cosmetic defects.  The advantages ofautogenous bone are that it provides osteogenic cells for phase I bone torrnation, and no tmrnunologtc response occurs.A disadvantage is that this procedure  necessitates

Posted by: brianna

Share This