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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