bone grafts used in various fractures.pptx

use of bone graft in various fractures

1. Dr. BHOSALE SUMIT Junior Resident-1 Dept. of Orthopedics Dr . PRAMOD SARKELWAD DR.DEEPAK AGRAWAL ASSO. Professor and HOU PROF. and HOD Dept. of Orthopaedics Dept. Of Orthopaedics DUPMC & H DUPMC & H

2. BONE STRUCTURE 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

3. 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%

4. BONE GRAFTING 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.

5. USES 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

6. Bone Graft Uses To fill cavities or defects resulting from cysts, tumors, or other cause  To bridge joints and provide arthrodesis  To bridge major defects or establish the continuity of a long bone  To provide bone blocks to limit joint motion ( arthroereisis ) To establish union in a pseudoarthrosis  To promote union or fill defects in delayed union, malunion, fresh fractures, or osteotomies.

7. BONE GRAFT INDICATIONS Structural support of articular fracture Tibial plateau fracture Prevent post-op collapse Void filler to prevent fracture Cyst excision Improved healing of fracture and nonunions Speed healing Fewer nonunions To bridge joints and provide arthrodesis

8. MECHANISMS Osteoconduction Provides matrix for bone growth Osteoinduction Growth factors encourage mesenchymal cells to differentiate into osteoblastic lineages Osteogenesis Transplanted osteoblasts and periosteal cells directly produce bone

9. OSTEOINDUCTION possess a chemical matrix, which provides molecular signals to the host that recruit or stimulate cellular activity for bone regeneration. The signals are the bone morphogenetic protein (BMPs), transforming growth factors (TGFs), platelet-derived growth- factor (PDGF).

10. OSTEOCONDUCTION This process supplies the three-dimensional configuration as a sca ff old for the ingrowth into the graft of host capillaries, perivascular tissue and osteoprogenitor cells from the recipient.

11. OSTEOGENESIS physiologic process whereby new bone is synthesized by graft cells or cells of the host. This new bone initially may be important for the development of callus during early graft incorporation.

12. C LAS S IF I C A T I ON Bone grafts Bone graft substitutes Autografts Allografts Cortical Cancellous Corticocancellod Vascularized Bone marrow aspirate Fresh Fresh frozen Fresh dried D e m i n e r a l i z e d freeze-dried Calcium p h o s ph a t e Calcium sulfate Collagen based matrices Hydroxyapatite T ri c a l c i u m phosphate o s teoco n d u c t i v e o s t e o i n duct i ve o s tegenect ive co m bined D e m i ne r a l i z e d bone matrix BMPS Bone marrow aspirates composites

13. Properties of auto and allografts

14. TYPES OF BONE GRAFTS Autograft Allograft Bone graft substitutes Most have osteoconductive properties Osteoinductive agents rhBMP-2 (Infuse) and rhBMP-7 (OP-1)

15. AUTOGRAFTS

16. AUTOGENOUS BONE GRAFT “Gold standard” May provide osteoconduction, osteoinduction and osteogenesis Drawbacks Limited supply Donor site morbidity

17. CORTICAL BONE GRAFTS Less biologically active than cancellous bone Less porous, less surface area, less cellular matrix Prologed time to revascularizarion Provides more structural support Can be used to span defects Vascularized cortical grafts Better structural support due to earlier incorporation

18. Autogenous Cortical Bone Grafts Sources: Ribs Fibula Crest of the ilium (also called as tricortical graft) It can be of two types: Conventional non vascular Vascularized bone graft

19. Non vascular versus vascular bone graft Non vascular Mainly osteoconductive with littile osteoinductive and no osteogenic properties. Revascularisation is slow till cortex is resorbed. Remodelling -2years Used in defects <6cm Vascular It has immediately restored blood supply More viable, more survival of osteocytes Can be used in defects upto 12 cm or even in inadequate host.

20. CANCELLOUS BONE GRAFTS Three dimensional scaffold (osteoconductive) Osteocytes and stem cells (osteogenic) A small quantity of growth factors (osteoinductive) Little initial structural support Can gain support quickly as bone is formed

21. VASCULARIZED GRAFTS Bone is transferred with its blood supply which is anastomosed to vessels at recipient site. Available donor sites: Iliac crest (with one circumflex artery) Fibula (peroneal artery) Radial shaft (interosseus artery )

22. AUTOGRAFT HARVEST Cancellous Iliac crest (most common) Anterior- taken from gluteus medius pillar Posterior- taken from posterior ilium near SI joint Metaphyseal bone May offer local source for graft harvest – Greater trochanter, distal femur, proximal or distal tibia, calcaneus, olecranon, distal radius, proximal humerus

23. AUTOGRAFT HARVEST Cortical Fibula common donor Avoid distal fibula to protect ankle function Preserve head to keep LCL, hamstrings intact Iliac crest Cortical or tricortical pieces can be harvested in shape to fill defect

24. Iliac crest graft

25. Complications of iliac crest graft Full thickness iliac crest graft lead to herniation. The lateral femoral cutaneous and ilioinguinal nerves are at risk during harvest of bone from the anterior ilium Alter the contour of the anterior crest, producing significant cosmetic deformity Arteriovenous fistula, pseudoaneurysm, ureteral injury, anterior superior iliac spine avulsion, and pelvic instability

26. Tibial graft harvest

27. Disadvantages of tibial graft Normal limb is jeopardized Increased duration of surgery Protected weight bearing for atleast 6 to 12 months .

28. Bone graft from fibula Entire proximal two third of the fibula can be used for bone graft The proximal rounded configuration of the fibula is covered with hyaline cartilage. May replace distal radius or even distal third of fibula The middle third of fibula can serve as the peroneal artery based vascular graft

29. Points to remember for fibular bone graft The peroneal nerve must not be damaged; The distal fourth of the bone must be left to maintain a stable ankle The peroneal muscles should not be cut .

30. AL L O G R A F T S

31. Used in small children where suffiecient graft is not available from donor site In adults where large defects have to be filled like: Periprosthetic long bone fracture Revision Total joint surgeries. Reconstruction after tumor excision

32. BONE ALLOGRAFTS Available in various forms – Processing methods may vary between companies / agencies Fresh Fresh Frozen Freeze Dried

33. FRESH BONE ALLOGRAFT Limited time to test for immunogenicity or diseases Highly antigenic Risk of transmission of diseses considerable risk of rejection (about 50%) Use limited

34. FRESH FROZEN ALLOGRAFTS Fresh frozen bone (FFB) is exposed to temperatures below -70°C Less antigenic Time to test for diseases Strictly regulated by FDA Preserves biomechanical properties Good for structural grafts

35. FREEZE-DRIED BONE ALLOGRAFTS • To prepare a freeze-dried bone allograft (FDBA), in addition to freezing, the donor bone is defatted, the bone marrow is removed, and it is dehydrated using different solvents . Even less antigenic Time to test for diseases Strictly regulated by FDA Can be stored at room temperature up to 5 years Mechanical properties degrade

36. DEMINERALIZED FREEZE-DRIED BONE ALLOGRAFT (DFDBA) T he HA skeleton of the allograft is removed using hydrochloric acid, with the aim of exposing the osteoinductive molecules in the allograft additionally

37. BONE GRAFT SUBSTITUTES

38. BONE GRAFT SUBSTITUTES They are synthetic or composite materials used to fill bone defects and promote bone healing. Avoid morbidity of autogenous bone graft harvest Mechanical properties vary Most offer osteoconductive properties Some provide osteoinductive properties

39. Bone Graf t Substitutes Extender for autogenous bone graft Large defects Multiple level spinal fusion Enhancer To improve success of autogenous bone graft Substitute To replace autogenous bone graft

40. Bone Graft Substitutes

41. Ideal bone graft substitute Scaffolding for osteoconduction Growth factors for osteoinduction Progenitor cells for osteogenesis Biocompatible and biodegradable and mechanical properties similar to the surrounding bone Each substitute available nowadays fulfill only some of the criteria

42. BONE GRAFT SUBSTITUTES Resorption rates vary widely Dependant on composition Calcium sulfate - very rapid Hydroxyapatite (HA) – very, very slow Some products may be combined to optimize resorption rate Also dependant on porosity, geometry

43. Mechanical properties vary widely Dependant on composition Calcium phosphate cement has highest compressive strength Cancellous bone compressive strength is relatively low Many substitutes have compressive strengths similar to cancellous bone All designed to be used with internal fixation

44. C AL C IU M PHOSPH A TE Injectable pastes of calcium and phospate Norian SRS (Synthes/Stratec) Alpha BSM (Etex/Depuy) Callos Bone Void Filler (Skeletal Kinetics)

45. Norian SRS

46. Injectable Very high compressive strength once hardens Some studies of its use have allowed earlier weightbearing and range of motion

47. How it works ? – Provides a porous scaffold that resorbs overtime Osteoclast cells begin recycling the material at the junction between bone and cement almost immediately Growth factors and antibiotics can be added to the paste in order to compliment the natural regeneration process After healing, all of the cement is replaced with natural new bone tissue

48. CALCIUM SULFATE Osteoconductive void filler Low compressive strength – no structural support Rapidly resorbs May be used as a autogenous graft extender - Available from numerous companies - Osteoset, Calceon 6, Bone Blast, etc.

49. Pellets Pellet injectors Bead kits Allows addition of antibiotics Injectable May be used to augment screw purchase Calcium Sulfate

50. TRICALCIUM PHOSPHATE Wet compressive strength slightly less than cancellous bone Available as blocks, wedges, and granules Numerous tradenames Vitoss (Orthovita) ChronOS (Synthes) Conduit (DePuy) Cellplex TCP (Wright Medical) Various Theri names (Therics)

51. HYDROXYAPATITE Produced from marine coral exoskeletons that are hydrothermically converted to hydroxyapatite, the natural mineral composition of bone Interconnected porous structure closely resembles the porosity of human cancellous bone Coralline hydroxyapatite Cancellous Bone

52. Hydroxyapatite Marketed as ProOsteon by Interpore Cross Available in various size blocks & granules ProOsteon 500 Very slow resorption ProOsteon 500 R Only a thin layer of HA Faster resorption

53. COLLAGEN BASED MATRICES Highly purified Type 1 bovine dermal fibrillar collagen Bone marrow is added to provide bone forming cells Collagraft (Zimmer) Collagen / HA / Tricalcium phosphate Healos (Depuy) Collagen / HA

54. DEMINERALIZED BONE MATRIX Prepared from cadaveric human bone Acid extraction of bone leaving Collagen Noncollagenous proteins Bone growth factors BMP quantity extremely low and variable Sterilized which may decrease the availability of BMP

55. Available from multiple vendors in multiple preparations Gel Putty Strip Combination products with cancellous bone and other bone graft substitute products Demineralized Bone Matrix

56. Growth factor activity varies between tissue banks and between batches While they may offer some osteoinductive potential because of available growth factors, they mainly act as an osteoconductive agents Demineralized Bone Matrix

57. Bone Morphogenetic Proteins Produced by recombinant technology Two most extensively studied and commercially available – BMP-2 (Infuse) – BMP-7 (OP-1) Medtronics Stryker Biotech Used in treatment of non union and open tibial fracture

58. Graft Incorporation Hematoma formation Release of cytokines and growth factors Inflammation Development of fibrovascular tissue Vascular ingrowth Often extending Haversian canals Focal osteoclastic resorption of graft Intramembranous and/or endochondral bone formation on graft surfaces…….

59. Primary phase Hemorrhage Inflammation Accumulation of hemopoitic cells including neutrophills, macrophages, and osteoclasts Removal of necrotic bone

60. Osteoconductive factors released from graft during resorption and cytokines released during inflammation Recruitment and stimulation of mesenchymal stem cells to osteogenic cells Active bone formation

61. Second phase Osteoblasts lines dead trabeculae and lay down osteoid Haemophoitic marrow cells forms new marrow in transplanted bone Remodelling ie woven bone slowly being transformed into lamellar bone by coordinated activities of osteoblasts and osteoclasts. Incorporation of grafts

62. Host response to cancellous vs cortical BG In cortical bone graft first osteoclastic resorption then osteoblastic activity Where as in cancellous bone graft bone formation and resorption occurs simulaneously called creeping substitution Therefore cancellous bone graft incorporates quickly But does not provides immediate structural support

63. FACTORS INFLUENCING GRAFT INCORPORATION

64. Bone Bank It is a facilitiy to provide safe and efficient allograft material. Hosts should be screened for : infections,malignancies(except for basal cell carcinoma of the skin), collagen vascular diseases, metabolic bone diseases and presence of toxins.

65. Technique Bone is collected in clean and unsterile environment. It is nibbled to remove the articular cartilage. It can be sterilized by irradiation, ethylene oxide or strong acid( 0.55 % HCl) It is subject to deep freeze upto -70 to -80 degrees celcius(frozen) Freeze drying involves removal of water and vacuum packaging of the tissue

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