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BONE GRAFT
DR BARUN KUMAR PATEL
What is graft ?What is grafting?What are bone grafts ?History of bone graftingObjectives and rationale of bone graftingBiological concept of using bone grafts techniques
OVERVIEW
A viable tissue that after removal from a donor site is implanted with in a reciepient tissue is then restored repaired and regenerated.
what is grafting ? Grafting is a procedure used to replace/
restore missing tissue.
what is graft ?
what are bone grafts ?
bone grafts are the materials used for replacement or augmentation of bone.
The principles, indication and techniques of bone grafting were established before the metalurgic age of orthopedic surgery
The first recorded bone implant was performed in 1668
Lane and sandhu introduced internal fixation
Albee,henderson,campbell intoduce the principle of osteogenesis in bone grafting
HISTORY
osteoinduction – induce differentiation of stem cell into osteogenic cells
Osteoconduction- provide passive porous scaffold upon which new bone can form
osteogenesis- provide stem cell with osteogenic potential ,which directly lays down new bone
BIOLOGIC CONCEPT OF USING BONE GRAFT
Increase in clinical bone defect fill.
To preserve and augment bone for future bone grafting when required.
OBJECTIVES OF BONE GRAFTS
Fill cavities or defects resulting from cysts or tumors
Bridge joint and provide arthrodesis
Bridge major defects or establish continuity of long bone
INDICATION OF BONE GRAFTING
Provide bone block to limit joint motion(arthroereisis)
Establish union in a pseudarthrosis
Promote union or fill defects in delayed union , malunion , fresh fracture or osteotomies
CONT…….
Bone is transferred from one site to other in the same individual
Ideal as bone graft posses all characteristic necessary for new bone growth i.e
osteoconductivity, osteoinductivity osteogenicity
includes- cortical bone grafts cancellous vascularised bone grafts autologus bone marrow grafts
AUTOGRAFT
ADVANTAGE
no immune reaction
all three properties present
DISADVANTAGE additional surgery donor site morbidity -inflamation ,infection, chronic pain and cosmetic limited quantities of bone graft
Obtained from tibia fibula iliac crest
Used primarily for structural support
CORTICAL AUTOGRAFTS
Obtained from thicker portion of ilium greater trochanter proximal metaphysis of the tibia lower radius olecranon from an excised femoral head
More rapidly incoporated into host bone than cortical autografts
CANCELLOUS AUTOGRAFTS
Uses of cancellous bone graft
- excellent choice for non unions with <5 to 6 cm of bone loss and that do not required structural integrity - used to fill bone cyst or bone voids after reduction of depressed articular surface such as in tibial plateu fracture
Stable internal or external fixation is required for graft consolidation and fracture healing
PRIMARY PHASE - haemorrhage - inflamation - accumulation of haematopoietis cells including neutrophills, macrophages, and osteoclasts - removal of necrotic tissue
INCORPORATION OF GRAFT
- osteoconductive factors released from graft
during resorption and cytokines released during inflamation
- recruitment and stimulation of mesenchymal stem cells to osteogenic
cells
- active bone formation
- Osteoblasts lines dead trabecule lay down
osteoid - haemopoitic marrow cells forms new
bone in transplanted bone - remodeling i.e woven bone slowly being transformed into lameler bone by cordinated activities of osteoblasts and osteoclasts - incorporation of graft
SECONDARY PHASE
- In cortical bone graft first osteoclastic resorption than osteoblastic activity
- In cancellous bone graft bone formation and resorption occurs simultaneously called
creeping substitution-Therefore cancellous bone graft incorporate
quickly-But doesnot provide immediate structural
support
Host response to cancellous bone graft differs from cortical
Bone is transferred with its blood supply which is anastomosed to vessel at recipient site
Available donor sites iliac crest(with one circumflex artery) fibula(with the peroneal artery) radial shaft
VASCULARISED GRAFTS
Vascularised grafts remain completely viable and incoporated like that of fracture healing
CONT..
Graft is obtained from an individual other than the patient
used in small children where sufficient graft is not available from donor site in adults where large defects have to be filled like- periprosthetic long bone fracture revision total joint surgery reconstruction after tumor excision
ALLOGENIC GRAFTS
Cont..ADVANTAGE no donor site morbidity large amount can be usedDISADVANTAGE immune reaction risk of infection disease transmission reduced osteoinductivity and osteogenicity
Graft must be harvested under sterile condition and doner must be cleared for malignancy , syphilis, cmv and hiv
Antigenicity can be reduced by freezing (at 70 deg c) , freeze drying or by ionizing radiation
Demineralization also reduces antigenicity and enhances osteoconductive property
CONT…
GRAFTS OSTE-OGENESIS
OSTEO-CONDUCTION
OSTEO-INDUCTION
MECHANICAL PROPERTY
VASCULARITY
AUTOGRAFT
BONE MARROW
++ +/- + - -
CANCELLOUS
++ ++ + + -
CORTICAL + + +/- ++ -
VASCULARISED
++ ++ + ++ ++
ALLOGRAFT
CANCELLOUS
- ++ + + -
CORTICAL - +/- +/- ++ -
DEMINERALISED
- ++ +++ - -
BONE BANK Donor must be screened for bacterial ,viral(HIV,hepatitis) and fungal
infection , malignancy , collagen vascular disease , metabolic bone disease , and presence of toxins.
bone is harvested in a clean , nonsterile environment
sterilized by irradiation , strong acid or
ethylene oxide
Freeze dried for storage
CONT..
Bone substitutes are natural , synthetic or composit materials used to fill bone defects and promote bone healing
BONE GRAFT SUBSTITUTE
PROPERTY CLASSES
OSTEOCONDUCTION Calcium sulfate, ceramics, calcium phosphate cements, collagen, bioactive glass, synthetic polymers
OSTEOINDUCTION Demineralised bone matrix, bone morphogenic proteins growth factors, gene therapy
OSTEOGENESIS Bone marrow aspirate
COMBINED composites
CLASSIFICATION OF BONE GRAFT SUBSTITUTES
GRAFT CATEGORY MECHANISM OF ACTION
AVAILABLE FORMS
Demineralised bone matrix
Osteoconductive and osteoinductive
Putty , injectable gels, Injectable paste,Flexible sheets,Formable discs,Moldable putty,Preformed strips,Fibres mixed with cancellous chips
Calcium sulphate osteoconductive Moldable hardening paste, Pellets and beads injectable cement
BONE GRAFT SUBSTITUTES
Tricalcium phosphate
osteoinductive Granules, strips, putty,Extrudable forms,Preformed blocks
Coralline hydroxyapetite
osteoconductive Small granules,blocks
Calcium phosphate cement
osteoconductive Injectable cement,Packable cement
Collagen combination product
osteoconductive Hydroxyapetite and collagen in strips,Preformed collagen blocks with embedded tricalcium phosphate granules,Malleable collagen putty with embedded tricalcium phosphate
Synthetic resorbable
osteoconductive Granules,Plugs,Blocks,wedges
Recombinant BMP 2 osteoinductive Poweder carried on a collagen sponge
Recombinant BMP 7 osteoinductive Lyophilised powder reconstitutted to form wet sand material,Lyophilised powder reconstituted to form putty
CONT…
USES
Primarily as osteoconductive agent
Delivery medium for antibiotic
To fill small defects after bone resection in chronic osteomylitis
Contains stem cells and osteoprogenitor cells , which are able to transform into osteoblasts
Multiple small volume aspirate is obtained from iliac crest(four 1ml aspirates from separate site puncture)
Centrifugation of aspirate in order to concentrate the cellular contents has provided encouraging results in animal experiment
BONE MARROW ASPIRATES
BMPs are osteoconductive
BMP-2 and BMP-7 are manufactured using recombinant technique
Used in treatment of non-union and open tibial fracture
Used with a carrier which may be allograft, DMB, collagen or bioactive bone cement
BONE MORPHOGENIC PROTEINS
ONLAY CORTICAL GRAFT
graft is placed subperiosteally across the fragments without mobilizing the fragments .
Cortical graft was suplemented with cancellous bone for osteogenesis.
Advantages- - simple to do - blood suply of the fragments and the normal impacting forces of fracture is not disturbed
VARIOUS BONE GRAFT TECHNIQUES
Uses- - malunited , nonunited fracture of shaft of long bone - bridging joints to produce arthrodesis
Fixation is achived by internal or external metalic device
CONT…
DUAL ONLAY GRAFT
Two cortical onlay grafts are placed opposite each other on the host bone across the nonunion and are fixed with the same set of screws
They grip the fragments like a vise Uses- to fix nonunited short osteoporotic fracture near a joint
DUAL ONLAY GRAFT
ADVANTAGE Mechanichal fixation is better than fixation
by a single onlay bone graft
two grafts add strength and stability
Grafts form a trough into which cancellous bone may be packed
during healing the dual graft prevent contracting fibrous tissue from compromising transplanted cancellous bone
DISADVANTAGE -same as single cortical
grafts not as strong as metalic fixator devices
Extremity usualy must serve as a donor site if autogenous graft are used
Not as osteogenic as autogenous iliac grafts
The surgery necessary to obtain them has more risk
A slot or rectangular defect is created in the cortex of host bone then a graft of the same size or slighty smaller is fitted in to the defect
Ocaisonaly used in arthrodesis, particularly at the ankle
INLAY GRAFTS
Usefull for- filling defects or cavities resulting from
cysts, tumor for establishing bone blocks and for wedging in osteotomies
Cancellous grafts are usefull for arthrodesis of spine because osteogenesis is prime concern
MULTIPLE CANCELLOUS CHIP GRAFTS
Harvested from - anterior iliac crest using an acetabula reamer, - femoral canal using a reamer-irrigator- aspirator(large volume cancellous bone graft can be harvested)
CONT..
A massive hemicylindrical cortical graft from the affected bone is placed across the defect and supplemented by cancellous iliac bone
Suitable for obliterating large defects of the tibia and femur
Applicable for resection of bone tumor when amputation is to be avoided
HEMICYLINDRICAL GRAFTS/MASSIVE SLIDING GRAFT
Fibula graft is most commonly used.
Usefull for filling large defects in the diaphsial portion of bones of upper extremity
In children ,the fibula can be used to span a long gap in the tibia
WHOLE BONE TRANSPLANT
FACTOR POSITIVE NEGATIVE
local Good vascular supply at the graft site,Large surface area,Mechanical stability,Mechanical loading,Growth factors,Electrical stimulation
radiation,Tumor, mechanical instability,Local bone disease,Denervation,infection
systemic Growth hormoneThyroid hormoneSomatomedinsVitamins A and DInsulinParathyroid hormone
CorticosteroidsNSAID drugsChemotherapySmokingSepsisDiabetesMalnutritionMetabolic bone disease
LOCAL AND SYSTEMIC FACTOR INFLUENCING GRAFT INCORPORATION
tourniquet aplied to avoid excessive blood loss
Make a slightly curved longitudinal incision over the anteromedial surface of the tibia.
REMOVAL OF TIBIAL GRAFT
Because of the shape of the tibia, the graft is usually wider at the proximal end than at the distal end.
periosteum over the tibia is relatively thick in children and is sutured as a separate layer
in adults periosteum is thin and is sutured along with the subcutaneous tissue
CONT..
PRECAUTION 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
Disect along the anterior surface of the septum between the peroneus longus and soleus muscle.
REMOVAL OF FIBULAR GRAFTS
Protect the peroneal nerve by tracing it from the posteromedial aspect of of the distal end of biceps femoris tendon.
CONT..
Protect the anterior tibial vessel that pass between the neck of fibula and the tibia by subperiosteal dissection
After the resection is complete, suture the biceps tendon and the fibular collateral ligament to the adjacent soft tissues
CONT..
iliac crest is an ideal source of bone graft because –
it is relatively subcutaneous has ample cancellous bone has cortical bone of varying
thickness Removal of the bone carries minimal risk usually there is no significant
residual disability
REMOVAL OF ILIAC BONE GRAFT
Large cancellous and corticocancellous grafts may be obtained from the anterosuperior iliac crest and the posterior iliac crest.
In children the physis of the iliac crest is preserved together with the attached muscle
CONT..
Generaly only one cortex and the cancellous bone are removed for grafts
the fractured crest
along with the apophysis is replaced in contact with the remnanat of the ilium by nonabsorbable suture.
CONT..
CONT.. INCISION along the subcutaneous border of the
iliac crest at the point of contact of the periosteum with the origins of the gluteal and trunk muscles
When the crest of the ilium is not required as part of the graft, split off the lateral side or both sides of the crest in continuity with the periosteum
Wolfe-kawamoto technique of taking iliac bone graft
Full thickness coronal segment of ilium
◦ Hernia devlops if full thickness massive grafts were taken.
◦ The superior cluneal nerves are at risk if dissection is carried farther than 8 cm lateral to the posterior superior iliac spine
Complication of iliac bone graft
superior gluteal vessels can be damaged by retraction against the roof of the sciatic notch
Removal of large full-thickness grafts from the anterior ilium can result in significant cosmetic deformity
Arteriovenous fistula, pseudoaneurysm, ureteral injury, anterior superior iliac spine avulsion, and pelvic instability
Cont..
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