Bone grafts

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Bone grafts

  1. 1.  Bone is not a uniformly solid material, but rather has some spaces between its hard elements.  CORTICAL /COMPACT BONE - The hard outer layer of bones is composed of compact bone tissue, so-called due to its minimal gaps and spaces. Its porosity is 5–30%. - 80% of total bone mass of a skeleton - consists of haversian canal and osteons
  2. 2.  CANCELLOUS/SPONGY/TRABECULAR BONE - Filling the interior of the bone is the trabecular bone tissue - composed of a network of rod- and plate- like elements that allow room for blood vessels and marrow. - accounts for the remaining 20% of total bone mass. - Its porosity is 30–90%
  3. 3.  Bone grafting is a surgical procedure that places new bone or a replacement material into spaces between or around broken bone (fractures) or in holes in bone (defects) to aid in healing.
  4. 4.  Used to repair bone fractures that are extremely complex, pose a significant risk to the patient or fail to heal properly.  Used to help fusion b/w vertebrae, correct deformities or provide structural support for fractures of the spine.  To repair defects in bone caused by congenital disorders, traumatic injury, or surgery for bone cancer.  Also used for facial or cranial reconstruction
  5. 5.  OSTEOGENESIS  OSTEOINDUCTION  OSTEOCONDUCTION
  6. 6.  Hemorrhage  Inflammatory response  OSTEOGENESIS - formation of new bone by the cells contained within the graft.  OSTEOINDUCTION involves the stimulation of osteoprogenitor cells to diffr. into osteoblasts that begin new bone formation. Most widely studied type of osteoinductive cell mediators in grafts are bone morphogenetic proteins (BMPs).
  7. 7.  OSTEOCONDUCTION  bone graft material serves as a scaffold for new bone.  Osteoblasts from the margin of the defect utilize the bone graft material as a framework upon which cells spread and generate new bone
  8. 8.  To promote union as in - Fresh fractures - Delayed union - Malunion - Osteotomies
  9. 9.  To bridge joints and thereby provide arthrodesis.  To bridge major defects or establish the continuity of a long bone.
  10. 10.  To fill cavities/defects secondary to - Trauma - Tumor - Infections and other conditions
  11. 11. 1)based on the donor origin - autograft - allograft - xenograft 2)based on composition -cortical -cancellous -osteochondral
  12. 12. 3) Blood supply:  Non-vascularised  Vascularised 4) Preservation - fresh - frozen - freeze dried - demineralized
  13. 13. 5) based on anatomical features - epiphyseal -metaphyseal -diaphyseal
  14. 14.  Bone harvested from the patient’s own body.  Gold standard - sufficient bone of the sort required is available & at the recipient site, there is a clean vascular bed.  Iliac crest – commonest site.
  15. 15. SOURCES 1) Cortical bone graft – for filling bone gaps Tibia mainly, iliac crest & fibula also. 2) Cancellous bone graft – for osteogenic purpose (eg: non-union).  Thicker portions of the ilium, greater trochanter, proximal metaphysis of the tibia, lower radius, olecranon or from an excised femoral head. 3) Whole bone graft – fibula.
  16. 16.  Cancellous grafts become incorporated more quickly & more completely than cortical grafts  The graft stimulates an inflammatory response with the formation of a fibrovascular stroma; through this, blood vessels & osteoprogenitor cells can pass from the recipient bone into the graft.
  17. 17.  donor site morbidity  Ambulation is delayed until the defect is partially healed  pain and infection at the site from which the graft is taken  Vascularized grafts - sophisticated microsurgical techniques are necessary & in major sites of loading , osseous hypertrophy may occur
  18. 18.  Muscle-pedicle bone grafting bone graft is taken along with pedicle of muscle (with intact blood supply which will supply blood to graft). - eg: non-union fracture neck of femur.
  19. 19.  Free vascularised grafting – bone (fibula) is taken along with the vessels supplying it. - eg:- the iliac crest (complete with one of the circumflex arteries), the fibula (with the peroneal artery). - Middle 1/3rd of fibula– used as a vascularised free autograft based on the peroneal artery and vein pedicle using microvascular technique - for treatment of large defects in cong pseudarthrosis of tibia.
  20. 20.  Graft obtained from a person other than the patient (live or dead).  Indicated in 1) small children, where the usual donor sites don’t provide cortical grafts large enough to fill a large cavity and when there is possibility of physeal injury. 2) aged persons 3) patients with poor operative risks  Usually taken from cadavers; it is typically sourced from a bone bank.
  21. 21.  There are three types of bone allograft available: 1. Fresh or fresh-frozen bone 2. Freeze-dried bone allograft (FDBA) 3. Demineralized freeze-dried bone allograft (DFDBA)
  22. 22.  Using allograft tissue from another person eliminates the need for a second operation to remove autograft bone or tendon.  It also reduces the risk of infection, and safeguards against temporary pain and loss of function at or near the secondary site.
  23. 23.  Bone variability because it is harvested from a variety of donors.  Longer time to incorporate with the host bone and may be less effective than an autograft.  Possibility of transferring diseases to the patient(viral transmissions).  Potential immune response complications.
  24. 24.  Graft obtained from another species.  Xenograft bone substitute has its origin from a species other than human, such as bovine.  Xenografts are usually only distributed as a calcified matrix.  S/E- foreign body reaction.
  25. 25.  Material derived from corals  Artificial bone can be created from ceramic such as calcium phosphates – porous str. (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.  Hydroxyapatite is crystalline calcium phosphate. Slow resorption
  26. 26.  made from hydroxylapatite, a naturally occurring mineral that is also the main mineral component of bone. They may be made from bioactive glass.  calcium carbonate - unpopular ;completely resorbable in short time which make the bone easy to break again
  27. 27.  These materials can be doped with growth factors, ions such as strontium or mixed with bone marrow aspirate to increase biological activity.  The presence of elements such as strontium can result in higher bone mineral density and enhanced osteoblast proliferation in vivo.
  28. 28.  The surgeon does a clinical examination, and conducts tests to determine the necessity of a bone graft,to determine the precise location of damage,exact amount of damage.  These tests include x-rays, MRI, CT scan  Arrange for blood in case a transfusion is needed  Proper nutrition to achieve good nutritional status before and after surgery.
  29. 29.  Single onlay cortical graft: was mainly used for ununited diaphyseal fractures , used for a limited group of fresh, malunited and ununited fractures. - bridging joints to produce arthrodesis, for both fixation and osteogenesis.  Dual onlay grafts: used in treating difficult and unusual nonunions or for bridging of massive defects. - eg: for nonunion near a joint - not as strong as metallic fixatives - not very osteogenic
  30. 30.  Inlay Grafts: - A slot or rectangular defect is created in the cortex of the host bone. - occasionally used in arthrodesis particularly at ankle. - complex and less efficient
  31. 31.  Peg Grafts- for fixation alone - weaker - use limited to non-union of medial malleolus and small bones of hand ,wrist or foot.  Medullary Graft - poor healing, interferes with endosteal circulation; rarely used except in metatarsals, metacarpals and distal radius.
  32. 32.  Osteoperiosteal Grafts- less osteogenic than multiple cancellous grafts ,and are rarely used.  Multiple cancellous chip grafts -widely used, best osteogenic material. -useful for filling cavities & cysts ,for establishing bone blocks, and for wedging in osteotomies. -Soft and friable.
  33. 33.  Hemicylindrical grafts- for obliterating large defects in tibia and femur. - massive hemicylindrical cortical graft from affected bone is placed across the defect and is supplemented by cancellous bone.
  34. 34.  Tourniquet to be applied.  Make a slightly curved longitudinal incision over AM aspect of tibia  Incise and reflect the periosteum  Drill a hole at each corner of the anticipated area.  Remove the graft by cutting through the cortex at an oblique angle.  Remove cancellous bone from the proximal end of tibia with a curet.
  35. 35.  Disadvantages - normal limb is jeopardised - Convalescence is prolonged - Tibia more prone for fractures for 6-12 months.
  36. 36. 3 points to be considered:- -peroneal nerve must not be damaged. -distal 1/4th of the bone must be left to maintain a stable ankle. -do not cut peroneal muscles.  Resect the middle 1/3rd Dissect along the anterior surface of septum b/w peroneus longus and soleus.
  37. 37.  Reflect peroneal muscles anteriorly.  Start stripping till fibula exposed.  Drill holes through fibula at the anticipated area of graft.  Graft harvested
  38. 38.  acquired bowel herniation (this becomes a risk for larger donor sites (>4 cm)).  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)
  39. 39.  injury to the ilioinguinal nerve  infection  minor hematoma (a common occurrence)  deep hematoma requiring surgical intervention  seroma  ureteral injury  pseudoaneurysm of iliac artery (rare)
  40. 40.  To efficiently provide safe and useful allograft material.  Uses thorough donor screening,rapid procurement, and safe sterile processing.  Donor screening for bacterial,viral and fungal infection.  C/I- malignancy( except BCC), collagen vascular diseases,metabolic bone dissease and presence of toxins.
  41. 41.  Bone can be harvested in a clean nonsterile environment, sterilised by irradiation,strong acid or ethylene oxide , and then freeze dried for storage.  Bone under sterile conditions , can be deep frozen (70-80 deg) for storage.  Fresh frozen bone is stronger than freeze- dried bone.  Cancellous bone can be obtained in a demineralised form.
  42. 42.  New BMP products are expected to be strong inducers of bone growth (osteoinductive).  These new products will be relatively expensive, but will grow bone better than the patient's own bone, eliminating the need for bone graft harvesting.  The INFUSE Bone Graft (rhBMP-2, BMP 7) has received approval.
  43. 43. THANK YOU

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