grafts, flaps and tissue transplantation yağmur aydin, m.d. university of istanbul, cerrahpasa...
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Grafts, Flaps and Tissue Transplantation
Yağmur AYDIN, M.D.
University of Istanbul, Cerrahpasa Medical FacultyDepartment of Plastic, Reconstructive and Aesthetic Surgery
Causes of Tissue Deficiency
Trauma
Tumoral resection
Congenital anamolies
RECONSTRUCTION
Tissue transplantation
RECONSTRUCTION LADDER
SIMPLE
Local Flaps
Primary Closure
Secondary Healing
COMPLEX Regional Flaps
Skin Graft
Free Flaps
Graft: tissue separated from its donor bed and relies on ingrowth of new vessels from the recipient tissuesVascularized graft (or flap): remains attached to donor blood supply or becomes revascularized via microvascular anastomoses to recipient vessels
Autograft : tissue transplanted from one location to
another within the same individual.İzograft : tissue transplanted from a genetically identical donor to the recipient (syngeneic mice or human monozygotic twins)Allogreft (homograft) : tissue transplanted between unrelated individuals of the same speciesXenogreft (hetereograft) : tissue transplanted between different species
Nomenclature
Tissue TransplantationAutologous
Skin Dermis, fat, fascia Cartilage Bone Muscle Nerve
AllogeneicXenogeneicAlloplastic materials
Metallic Seramic Polimeric
Tissue Transplantation
Basis of modern Plastic SurgeryLimited donör area for autologous tissue transplantationNonautologous tissues (Allogeneic, Xenogeneic) may be used for tissue deficiencyThey are rejected because of foreign body antigensLong term immunosupression need to survive longer
Advantages of Autologous Tissue Transplantation
Easy integration
No rejection response
No fibrous capsule formation around the transplant
Disadvantages of autologous tissue transplantation
Donor area morbidity
Limited supply
More complex and longer operation
Resorption and deformation
Immunologic Response to Allogeneic and Xenogeneic Tisuues
Cellular response (T cells)Humoral immunologic response(B lymphocytes)Matching of HL-A, HL-B ve HL-DR antigens are important factor in long term survivalHyperacute rejection occurs within the first few minutes to hours after transplantation Rejection response is less to tissues which have few cells and lesser vascularity (cornea, cartilage)
Biomaterials1. Metals: used in plating systems for craniomaxillofacial internal
fixation (Stainless steel, cobalt-chromium, pure titanium, titanium
alloys,and gold )
2. Calcium ceramics: used as bone graft substitutes
(Hydroxyapatite, Tricalcium phosphate, hydroxyapatite cement)
3. Polymers: used in both bone and soft tissue reconstruction
and augmentation (silicone, polyurethane, polyesters, nylon,
polyethylene, polypropylene, cyanoacrylates)
4. Biologic materials: used in the treatment of depressed scars
and facial wrinkles (collagen, fibrel, hyaluronic acid)
Advantages of Biomaterials
No donor site morbidity
Less operative time
Easy availability and unlimited supply
Fabricated according to patient needs
No resorption or deformation
Ideal Implant
BiocompatibleNontoxicNonallergenicNoncarcinogenicEasy to shape, remove, and sterilizeResistant to strainAble to be fabricated into specifically required formsProductive of no foreign-body inflamatuary responseMechanically reliableResistant to resorption and deformationNonsupportive of growth of microorganismRadiolucent ( not interfere with CT and MR imaging)
Disadvantages of Biomaterials
Rejection
Infection
Implant malposition or extrusion
Implant defects (broken, punctured)
Fibrosis around the implant because of foreign body response
Tissue Transplantation in Plastic Surgery
Skin Autograft, allograft, xenograft
Bone Autograft, allograft
Cartilage Autograft, allograft, xenograft
Nerve Autograft, allograft
Tendon Only Autograft
Fascia Autograft, allograft
Skin Embryology
Derived form both ectoderm and mesoderm
Ectodermal skin appendages develop with formation of epidermis at 11 weeks of gestation and complete at 5 months
Suface of Ectoderm : Epidermis,Pilosebaceous glands, Apocrine and eccrine sweat glands, Hair follicles, Nail units
Neuroectoderm: melamocytes, nerves, and specialized sensory units
Mesoderm : Sructural components of dermis
(macrophages, mast cells, Langerhan’s cells, Merkel cells, fibroblasts, blood and lymphatic vessels)
Skin Functions
The skin is the largest organ of the bodyProtect underlying structures from enviromental trauma by entry of pathogens and potentially toxic substancesMust allow considerable compressions and extentionsPassive regulation of intracellular fluid balance and active regulation of body temperature
Skin Autograft full thickness or partial thicknessrequire a recipient bed that is well vascularized and free of devitalized tissue and no bacterial contamination (<105 microorganisms per gram of tissue)Close contact between the skin graft and its recipient bed is essentialhematoma beneath the graft and insufficent immobilization are common causes of graft failureTo optimize take of a skin graft, the recipient site must be prepared before grafting
Skin Graft Survival
The transplanted skin derives its initial nutrition via serum from the recipient site in a process called “plasmatic imbibition” last for 24 to 48 hours
The graft then gains blood supply from the recipient bed by ingrowths of blood vessels. This process of “inosculation“ begins within 48 hours
Partial Thickness Skin Grafts
Consist of entire epidermis and a portion of dermis
A thin split-thickness harvest site will generally heal within 7 days
SSG’s can be taken from anywhere on the body
The abdominal wall, buttocks, and thigh are common donor sites
for SSG’s
Skin Graft Donor Site Healing
The donor site epidermis regenerates from the immigration of epidermal cells originating in the hair follicle shafts and adnexal structures left in the dermis
A thin split-thickness harvest site (less than 10/1,000 of an inch) will generally heal within 7 days
Full-thickness skin graft harvest sites heal by primary intention
Most Common Causes of Autolous Skin Graft Failure
Hematoma, Seroma
Infection (> 105 organism/1gr tissue)
Shear force ( inadequate immobilization)
Poor vascularized bed (fibrozis, radiotherapy; exposed bone, cartilage, or tendon devoid of its periosteum, perichondrium, or paratenon)
Full Thickness Skin Graft
contains the entire dermis (adnexal structures such as sweat glands, sebaceous glands, hair follicles, and capillaries)
Usually harvest from skin is thin(upper eyelid, postauricular area, or supraclavicular area). Other harvest sites are hairless groin, antecubital fossa, distal forearm, prepuce
FSG harvest sites can be closed primarily or applied a SSSG from another body part
Require well-vascularized bedprone to increased graft contraction and hypertrophic scarringPoor color and texture matchabnormal pigmentationLess than ideal cosmetic resulthighly susceptible to trauma
Better graft “takeLarge available donor siteExpansion of the split-thickness skin graft by meshing with expansion ratios from 1:1.5 to 1:9
Take under less favorable condition
The less secondary contracture
Good color and texture match
Excellent cosmetic result
Potential for growth
less reliable graft “take
Limited donor site
Full thickness skin graft Split thickness skin graft
Advantages &Disadvantages
Sensory return
Graft sensation is regained as nerves grow into the graft
Sensory recovery begins at around 4-5 weeks and is completed by 12-24 months
Pain,light touch, and temperature return in that order
Skin Allografts
Skin allograft was the first “organ” transplant achieved and constituted the foundation of modern transplant immunology
strongly antigenic and is subject to rejection ( 10 days in burns)
Obtained from relatives or human corpse (frozen and stored)
beneficial in large burns (> % 50) as a biologic dressing
Frozen and stored or may be used immediately with cyclosporine immunusupression
Skin Xenografts
Pig skin grafts can be used as temporary biologic dressings in large burns
Hyperacute rejection occurs within the first few minutes to hours after transplantation
Advantages Cheap, easy availablility, easy storage and sterility
Skin Flaps
Unlike a graft, a flap has its own blood supply
Consist of skin and subcutaneous tissue that are transferred from one part of the body to another with a vascular pedicle or attachment to the body being maintained for nourishment
When skin flaps are used?
Covering recipient beds that have poor vascularity
Reconstructing the full thickness of the eyelids, lips, ears, nose, and cheeks; and padding body prominencies (i.e., for bulk and contour)
It is necessary to operate through the wound at a later date to repair underlying structures
Muscle flaps may provide a functional motor unit or a means of controlling infection in the recipient area
The Cutaneous Arteries
arise directly from the underlying source (segmental or distributing) arteries, or indirectly from branches of those source arteries to the deep tissuesFrom here the cutaneous arteries follow the connective tissue framework of the deep tissues, either between (septocutaneous) or within the muscles (musculocutaneous)They then pierce that structure, usually at fixed skin sites. ultimately reaching the subdermal plexus
Schematic diagram of the direct (d) and indirect (i) cutaneous perforators of a source artery and their relationship to the deep fascia (arrow), the intermuscular septa and muscle (shaded area)
Direct Cutaneous Vessels Indirect Cutaneous Vessels
Patterns of Blood Supply to the Skin
Direct cutaneous pedicle
Fascicutaneous pedicle
Musculocutaneous pedicle
Z Plasty
revise and redirect existing scars or provide additional length in the setting of scar
Angles of Z-plasty Theoretical gain in length(%)30-30 2545-45 5060-60 7575-75 10090-90 120
Vascular territories of the most commonly used axial pattern flaps
Groin Flap
based on the circumflex superficial iliac artery and vein
Free Composite Grafts
Contain two or more tissue (dermis-cartilage, dermofat, skin-muscle, pulpa)
Need well-vascularized bed
Poor vascularization and graft taking
Stasis and necrosis in the graft because of insufficent venous and lymphatic return
Results is not optimal Limited size Contraction Contur problem because of bowing
Enhancing Survival of Composite Grafts
Well vascularized bed, no fibrosis
Atrumatic technique
Postoperative cooling
> 5 mm distant from the nearest vascular bed is at risk for necrosis
Center of graft is never more than 5-8 mm away from a blood supply
Composite Grafts in Plastic Surgery
Nose (from ear or nasal septum) Nasal ala Columella Lateral nasal wall Nasa roof and lining reconstruction Short nose Septal perforation
Ear Helical rim Chonca Tragus
Eyebrow (scalp)Nipple (opposite nipple or ear lobule)Eyelid (septal chondromucosal graft)
Bone Transplantation
Both bone autograft and allografts are used for bone defect reconstructionBone xenografts are not used nowadays because of sequester of all viable osteocyteCortical or cancellous bone graftRevascularization of cortical grafts may take a few monthsRevascularization of cancellous bone grafts are more rapidHealing of vascularized bone grafts are better. Particularly suitable in a field after trauma, cronic scarring, or prior radiation. Biomecanically are superior to nonvascularized grafts
Bone Graft Donor Areas
Cranium (cortical)
Thorax (split rib grafts)
İliac ( good quality cortical and cancellous bone source)
Tibia (cancellous )
Others Distal radİUs, proXimal ulna (hand surgery) Fibula (esp. vascularized flap) Metatars
Tendon Grafts
Only if primary or delayed primary repair is not feasible
Contrindicated if there is stiff joints, adherent extensor tendons, and inadequate skin cover
Only autograft
Unacceptable amount of host reaction and adhesion after allografts and xenografts
Cartilage Grafts
Cartilage has no intrinsic blood supplyThe use of cartilage autografts is widespread and includes nasal, auricular, craniofacial skeleton, and joint reconstructionCartilage is immunologically privileged due to the shielding of chondrocytes by its matrix, which is only weakly antigenicBoth chondrocytes and matrix are subject to xenogeneic mechanisms of rejection with a generally poorer outcome in comparison. There is only small number of usage
Donor Areas for Cartilage Graft
Choose according to aim Costal cartilage(7,8 ve 9. ribs)
Ear reconstruction Nasal dorsal and alar area reconstruction
Ear cartilage: Lower eyelid support Nipple-aerola reconstruction Orbita floor reconstruction Temporomandibular joint repair
Nasal septal cartilage Aestetic Rhinoplasty and Nasal reconstruction
Nerve Grafts
The nerve graft acts as a biologic conduit for the regenerating axons
Vascularized nerve grafts are theoretically advantageous particularly in scarred beds
Other “conduits” used as nerve grafts have included autologous vein, silicone tube seeded with Schwann cells, and freeze fractured autologous muscle
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