Surgical Grafts for Skin, Tendon, and Bone Healing

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Simplifying the Science - Advances in Wound, Tendon, and Bone Grafts J. Palmer Branch, DPM Comprehensive Foot and Ankle, LLC www.comprehensivefootandankle.net [email protected] Lilburn, GA (770-921-8800) Cumming, GA (770-886- 6833) 1

description

Overview of skin, tendon, & bone grafts used in foot & ankle surgery.

Transcript of Surgical Grafts for Skin, Tendon, and Bone Healing

Advances in healing of diabetic ulcers

Simplifying the Science - Advances in Wound, Tendon, and Bone Grafts J. Palmer Branch, DPMComprehensive Foot and Ankle, LLC [email protected] Lilburn, GA (770-921-8800) Cumming, GA (770-886-6833)

11INTRODUCTION

2OverviewMany similarities in healing processSkin TendonBone

Understand the graft concept (allow for ingrowth of new tissue) - Science is secondary.

Understand the basic graft healing process and timing of events, then you can determine what to do and when and advance your techniques.3BASIC CONCEPT

The process of skin, soft tissue and bone graft healing is analogous to ivy growing into a lattice or scaffold.

Other products and specialized grafts stimulate the healing process itself- Growth factors- BMP- Magnetic bone stimulators4SKIN HISTOLOGY

1) Epidermis - stratified squamous epitheliumepidermal ridges2) Dermisa) Papillary layer - small blood vessels, lymph & nerves fine collagen & elastic fibersb) Reticular layer - vascular plexus, lymph, nerves & appendagescompact collagen fibers & thick elastic fibers3) Hypodermis (subcutaneous)mainly adipose tissue, sweat glands, blood vessels5Basics of wound healing

6Growth factors & wound healing

7Bone Structure

8Bone histology - micro

Woven bone with collagen matrixHaversian canal and nutrient artery9Bone trabeculation

Trabeculae 10Bone healing- Inflammatory cells- Soft callous formation- Transitions to hard callous

- Primary vs. Secondary bone healing primary facilitated by close contact, stability, compression

11Bone healingPhase 1 (Days 0-4)blood clot then fibrin network forms, TGP PDGF stimulate the chemotaxis and later proliferation of primitive mesenchymal cells

Phase 2 (Days 5-9)primitive mesenchymal cells differentiate into chondroblasts and chondrocytes subsequent production of cartilaginous matrix. This matrix is then invaded by capillaries

Phase 3 (Days 10-21) Mesenchymal Cell Differentiation Into osteoblasts and osteocytesType I collagen synthesis (Days 12 through 18)Multinucleated osteoclasts begin the process of bone remodeling. The osteoclasts and osteoblasts replace early bone and remaining calcified cartilage with bone ossicles.By Day 21, bone marrow differentiation occurs

12Bone healing pictures

Active osteoblasts laying down compact boneOsteoblasts with multiple nuclei and foamy cytoplasmTendon Structure

14TENDON NORMAL VS ABNORMAL

A NORMAL, B ACUTE RUPTURE, C TENDINTIS, D- TENDINOSIS15Tendon healing processWeek 1 - Hemostasis, inflammation, growth factor release Tendon ends retract / phagocytosis of debris- Fibroblastic splint / tendon callousWeek 2 Vascularity of paratenon increases*Preservation of paratenon in surgical repair important.- fibroblasts continue to proliferateWeek 3 - Collagen fibers come together and align longitudinally- Classic stage for mobilization, but newer PT/ Achilles rehab studies call for earlier mobilization to reduce adhesions.Week 4 - Inflammation reduces- Improved gliding function- Increased parallel organization and growth of collagen fibers

* Maturation at about 8 weeks.* Repaired tendon typically has at best around 80% of original strength.16GRAFTS

Sorry best phagocytosis shot I had.17Split-thickness skin grafts

18Classic problems Donor site morbidityLimited supplyDifficulty healingLimited durabilityNew surgical products - scaffoldsGraftJacket Freeze-dried human dermis Originally released as a cover for periosteumProvides a collagen scaffold for ingrowth of granulation tissueBrigido - Compared single application of GraftJacket to sharp debridement, weekly dressing changes - 85.7% healed with GraftJacket at 12 weeks vs. 28.6% healed at 12 weeks without.

Alloderm similar product / human dermis, often used in burn woundsGammaGraft Irradiated human dermis.Pegasus (OrthoAdapt) Recently purchased by Synovis Life TechnologiesSource is equine pericardiumRejection a possibility

1919GraftJacket healing diagrams

GraftJacket Sample case21Infected wound dehiscence ulcer 6 weeks s/p I & D, & IV antibioticsAfter debridement

GraftJacket applied in OR (Osteoset antibiotic beads and VAC also used.)

GraftJacket Sample case221 week post-op Osteoset absorbable antibiotic beads also noted2 weeks post - op8 weeks post-opWound healed around 16 weeks post - opBusiness Template23

23Topical - Growth Factors Stimulate the healing process Dermagraft Genzkow showed higher percent at 50% and 100% healed at 8 and 12 weeks vs. control. At 8 weeks 50% of ulcers healed with Dermagraft vs. 8% control 75% vs. 23% fully healed at 12 weeks.Apligraf

Future Stem cell-derived products24Skin substitute / matrix dressingsIntegra dermal replacement, bilayered allows for ingrowth of new skinDermal layer - Acellular porous lattice - fibers of cross-linked bovine collagen with GAG (glycosaminoglycans) Epidermal layer synthetic polymer ( polysiloxane)Oasis Porcine intestinal submucosa, provides extracellular matrix for tissue ingrowth.

25BONE GRAFT EFFECTSOsteoconduction Provides scaffold for new bone growth -

Osteoinduction Chemically stimulates new bone formation

Osteogenesis Generation of new boneAutograft only living cells / osteoblasts

Structure / strength hardening putty often best- tricortical wedge

Combination of above / multiple effects**Which is most important?- Depends on the situation26Bone graft materials - benefits

27Bone graft types / examplesAutogenous - Grafts harvested from patient.Donor Allograft bone chips, wedges, etc.XenograftCancelloPure(Wright) Bovine bone - cancellous wedges Biocleanse treated, terminally sterilizedProOsteon (InterPore/BioMet -coral)Synthetic / ceramic bone replacements Hardening Putty / InjectableProdense, MIIG - WrightNorien CRS FastSet Putty (Synthes)Particulate or prefab products Calcium sulfate Nexa Orthopedics wedges and plugsTitanium Biofoam Evans wedges

28Bone graft types / examplesOsteoinductive substancesDBM Grafton (Osteotech), AlloMatrix(Wright), Biomet DBM putty BioMet Platform injectable(Biomet), DBX (Synthes)Bone marrow aspirate harvest system Symphony(DePuy), Magellan (Medtronic)Adult stem cellsTrinity Multipotential Cellular Bone Matrix (recent poster at ACFAS)Recombinant human bone morphogenetic protein-2 INFUSE Bone Graft is rhBMP-2 (manufactured BMP)Combination productsProStim - ProDense with DBMOrigen DBM Bioactive glass particulate scaffold / chips with DBMIgnite Power Mix - injectable scaffold of demineralized bone matrix with aspirated red bone marrow.

29Bone Grafts - traditional

30Donor site morbidity must be considered (e.g. infections, chronic pain, scarring)Cancellous chipsOsteosetAbsorbable Antibiotic beads {e.g. Osteoset calcium sulfate} Release antibiotic mixed into the beads into the surgical woundUsually Vancomycin, Tobramycin,and Gentamycin are used.Allows for extremely high local levels of antibiotic into the wound - usually several times over the MIC (minimal inhibitory concentration) for some antibiotic-resistant bacteria.

**Polymethymethacrylate removable beads or free-formed spacers may be used for this purpose as well. - must be removed.

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Pro-Dense Injectable Regenerative GraftImmediate intra-operative strengthPredictable bone regenerationStronger than autograft 645% greater compressive strength at 13 weeks vs. autograft *Faster, denser than autograft170% more new bone vs autograft at 13 weeks*Remodels to normal boneEasy-to use applicator

*Urban, et al in canine proximal humerus model, June, 2007

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33PRODENSELAPIDUS

34Prodense Evans Case35

INTRAOP9 WEEKS POST-OPEvans - ProDense + Tricortical wedge36

1 WEEK POST-OP3 MONTHS POST-OP6 WEEKS POST-OPEvans & T-N fusionSoft lateral calcaneusTricortical wedge + ProDense injectionRapid ProDense incorporation , slow tricortical wedge incorporationBone stimulators

Stimulate the bone healing process - Piezoelectric effect / electronegativity at fracture site- Increase growth factor and receptors- Increase affect calcium flow across membranes- Stimulate endothelial cell and capillary growth and capillary formation.Electromagnetic fields- External - Biomet / EBI, Physio-Stim, DonJoy CMF OL1000- Internal- Biomet OsteoGenUltrasound- Exogen (Low intensity pulsed ultrasound)- Mechanical pressure waves transmit through skin and soft tissue results in stimulated growth factors which stimulate bone healing process.37

GraftJacket Cryogenically processed human dermis - Many applications - High tensile strength

400x magnified image of non-implanted material demonstrating preserved vascular channelPreserved vascular channels act as template for rapid revascularizationGRAFTJACKET Regenerative Tissue MatrixTypical Freeze-dryingIce crystals damage collagen/elastinBody then recognizes as foreignInitiates inflammatory or immune responseCryogenic ProcessingPrevents ice crystal formationStructurally intact matrix with:-Collagen-Elastin-ProteoglycansPreserved vascular channels

3939The patented cryogenic processing of the GRAFTJACKET Matrix prevents ice crystal formation thus minimizing any damage to the matrix to help avoid an inflammatory response to the graftBy protecting the matrix through the processing steps, the vascular channels are preserved as demonstrated in this electron micrograph. Dermis is very vascular making the GRAFTJACKET matrix an excellent graft template for many different tissue type repairs.These channels act as a template for rapid initial revascularization through what is called inosculation. This is simply communication of existing blood vessels in the body with the preserved channels in the graft. New blood vessels will be formed later through the process known as angiogenesis.Tendon Grafts - examplesGraftJacket (standard, MaxForce, MaxForce Extreme)RestoreCuffpatchBiotape XMAcellular porcine dermal matrixOrthAdapt (formerly Pegasus, now Synovis Life Technologies)rejection40

RightAchilles tendon repair. Severe rejection of Pegasus / OrthoAdapt graft with large foreign body granuloma. Growth factors in tendon healingPlatelet Derived Growth Factor (PDGF) produced shortly after tendon injury stimulates the production of other growth factors.

TGF-beta complex active during the inflammatory and repair phases of tendon healing especially in the in the repair of injured tendons. TGF-beta 1 aids an extra cellular matrix deposition; however, its over expression results in tissue fibrosis. TGF-beta 2 functions similarly to TGF-beta 1.TGF-beta 3 has been shown to improve tissue scarring. Highest levels of TGF-beta receptor expression occur at day 14 post injury and decrease until day 56 post injury.

Vascular Endothelial Growth Factor (VEGF) stimulates endothelial cell proliferationenhances angiogenesis and increases capillary permeability. VEGF RNA expression is detected at the repair site 7 days post injury with peak levels at 10 days post injury.

42GraftJacket Achilles Tendon Repair standard cannoli wrap technique

Improved strength allows for earlier rehab.Can be difficult to close paratenon if thick graft used. 43Tendon transfers / weavesClassic advantages Improved strength- Earlier rehab to prevent adhesionsClassic disadvantage- Loss of donor tendon function / donor site morbidity- Additional surgical site and prolonged OR time.

Pulvertaft weave44

FHL tendon transfer Achilles repairAlternate technique to cannoli wrap

45GraftJacket Strip & Shoelace weave46

1 - Reapproximate tendon ends2 - Place inlay strip3 Tie in weave stripGraftJacket Strip & Shoelace Weave

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5 Weave strip is woven in a shoelace pattern similar to Pulvertaft techniqueGraftJacket Strip & Shoelace Weave48

6 - Closure of the paratenon is facilitated.

Creating a GraftJacket weave strip

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GraftJacket Strip & Shoelace Peroneal Tendon Repair

50GraftJacket Strip & Shoelace Peroneal Tendon Repair51

Other tendon grafts / materials

Flexiglide - - absorbable mesh graft- limited strength- mostly helpful in adhesion preventionTenoglide similar, more friable, difficult to handleOther future graft types

Stem cells in surgical thread used to repair Achilles tendon.

Hardening Injectable bone cement immediate stabilization, limited scaffold effect53Selection of appropriate advanced therapy

How can the healing process be best enhanced for the situation?Applying medical expertise and judgment to each situation Medicine is often more an art than a science. Know what each product can do particular indications and benefits of each device or treatment.54SummaryUnderstand the basic science.Scaffold effect to reduce the defect.Strength when needed for bone and tendon.Growth factors and other means to speed healing when needed.Use the basic concept to enhance explaining planned procedures to patients.Be able to take your surgical plan to the next level when indicated by not getting hung up on the details of the basic grafting process.

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56THANK YOUJ. Palmer Branch, DPM [email protected] Comprehensive Foot & Ankle, LLCwww.comprehensivefootandankle.net Lilburn, GA (770-921-8800); Cumming, GA (770-886-6833)