Skin Graft _24.pptx

Bedru mohammed -skin graft ppt

1. Principles of Skin Grafts By : Dr.Yohannes(PRSF-1) Moderator: Dr. Helina(Consultant of plastic and Reconstructive surgeon)

2. Outline Introduction Anatomy of skin Review Reconstructive ladder Principles of skin graft Reference

3. Introduction The origin of skin and soft tissue grafts dates back 3000 years. Sanskrit texts record the use of free skin grafts to repair mutilations of the nose, ear and lip. I n 1817, Sir Astley Cooper used a full-thickness skin graft from a man’s amputated thumb to provide coverage for the remaining stump. In 1823, Buenger recorded the first successful free skin autograft in Europe.

4. Introduction cont ... The current technique of skin grafting is attributed largely to Reverdin , pinch grafts in 1869 and described homografts in 1872. Ollier and Thiersch described the thin STSG in 1872 and 1886, respectively. The FTSG was reported by Wolfe in 1875 and Krause in 1893.

5. Anatomy of the Skin The largest organ in the human body The skin represents app.8% of our TBW,with a surface area of 1.2–2.2m 2 . The skin is 0.5–4.0mm thick and covers the entire external surface of the body Has t hree properties essential for understanding reconstruction : Elasticity Extensibility Resilience two distinct layers :epidermis and dermis.

6. Anatomy of the Skin

7. Epidermis Varies in thickness from 0.04mm in the eyelids to 1.6mm in the palms. No blood vessels and relies on diffusion from underlying tissues. Principal function of epidermis is protection by the process of cornification, producing layer of dead cells.

8. Dermis Mainly composed of collagen , elastic fibers and ground substance. Contains all the nerves , vessels , lymphatics and most of the glandular elements of the skin. The mechanical behavior, i.e the ability to stretch, resilience of the skin is primarily related to collagen & elastin content. Dermis has two layers : superficial papillary and deeper reticular layer.

9. Blood Supply of the Skin The cutaneous arteries arise either directly from the underlying source arteries, or indirectly from branches of those source arteries to the deep tissues, forming subdermal plexus. Direct cutaneous vessels Fasciocutaneous (septocutaneous) & axial vessels Indirect cutaneous vessels Musculocutaneous

10. Schematic Illustration of Direct and Indirect Cutaneous Vessels

11. 6 layers of vascular plexuses

12. 3D vascular territories of skin and its underlying deep tissues supplied by named main source artery and its accompanying vein s Each angiosome is linked to its neighbor at every tissue level, by either A true connection without change in vessel caliber Reduced “choke” anastomosis. can potentially dilate to the caliber of a true anastomosis D esigning skin flap dimensions. Angiosome

13. Reconstructive Ladder Provides systematic approach to wound closure. Emphasizes selection of simple to complex techniques based on local wound requirements and complexity. Each option is considered based on viability, risk of complication , best functional and aesthetic result for the patient

14. Terminologies Autografts – One part of the body to another. Isograft / Syngraft - The donor and recipient are genetically identical e.g. monozygotic twins Homografts /Allograft – Genetically different individual of the same species. Xenografts – One species to an individual of another species.

15. Skin Grafts Skin grafting involves the free transfer of epidermis with varying amounts of the underlying dermis to cover and heal an open wound. Are a standard option for closing defects that cannot be closed primarily. Modern skin grafting methods include split thickness grafts , full thickness grafts , and composite tissue graft .

16. Indications Any traumatic wound that cannot be closed primarily Defects after surgical resection Burn reconstructions Scar contracture release Congenital deficiencies of skin such as syndactyly, vaginal atresia Hair restoration

17. Absolute Contraindications Wounds with avascular bed Infected wounds Wounds due to malignant neoplasia Wounds with exposed bones ,tendon and deep space

18. Mechanisms of Skin Graft Healing PHASE 1- PLASMA IMBIBITION Initial ischemic phase Lasts approximately 24 to 48 hrs P lasma leaks from recipient capillaries into the wound bed-graft interface Fibrin adhere the graft to the wound bed. The grafts absorb serum, become edematous and gain as much as 40% of their initial weight M etabolism within the graft becomes anaerobic and metabolic demands of the graft also fall Serum absorbed from wound bed serves as temporary nourishment for the graf t ????

19. Mechanisms of Skin Graft Healing cont.. 2.Inosculation This mechanism in its traditional definition is no longer considered truly valid, Require close approximation of the cut ends of the wound bed and graft vessels

20. Mechanisms of Skin Graft Healing cont.. 3.Revascularization Starting from 2nd postop day Three theories 1. Theory of inosculation (Connection of graft and host vessels) 2. Theory of vascular ingrowth from recipient bed (angiogenesis and vasculogenesis) 3.R eperfusion by angiogenesis from the wound bed but hypothesizes that recipient-derived endothelial cells migrating into the graft

21. 4.Maturation Graft and surrounding tissues remodel and contract 1 year to complete maturation Disappearance of immature vessels

22. Split-thickness Grafts Contains 100% of the epidermis and a portion of the dermis. Further classified as thin , intermediate or thick . A typical STSG is 0.3-0.5 mm(0.012-0.018 inch) thick. STSGs are commonly taken from the lateral thighs and trunk. Used when cosmetic appearance is not an issue, big wound that is too large to use a FTSG or if joints are not involved.

23. Split-thickness Grafts, cont … Advantages Survives better &takes well Resurface large wounds Donor site heals spontaneously repeated harvesting Disadvantages More fragile, don’t resist trauma Contract more on healing Poor characteristics of skin Functional than cosmetic They do not include full length of appendages, so unlikely to grow hair or to develop full sweat gland function.

24. Full Thickness Skin Graft FTSG should be considered in the reconstruction of aesthetically dominant (face) or functionally important areas (hand). FTSG are taken in an area where loose surrounding skin is available to achieve primary closure. Donor sites- buttock fold, inguinal fold, retroauricular region, supraclavicular, superior eye brows, hypothenar areas .

25. Full Thickness Skin Graft, cont … Advantages Minimal to no secondary graft contraction Excellent skin quality, stability Hair regrowth and skin appendage function Grow with the individual Disadvantages Limited availability Non-take risk is higher Need to close donor site

26. Preoperative Preparation Patient Optimization Recipient Site Preparation Donor Site Selection

27. Patient Optimization Treatment of any systemic infection Treatment of anemia and nutritional support when necessary . Treatment of comorbid medical illnesses if any

28. Recipient Site Preparation Must be well vascularized. Free of all necrotic / ischemic tissue, cellulitis , purulent drainage and significant edema. Hemostasis Low bacterial count (<10 5 m.o /gram) Granulation tissue can be heavily colonized and should be gently debrided back to the wound base. The recipient site should also be thoroughly irrigated prior to graft placement

29. Donor Site Selection Depends on the desired size , hair pattern , color , texture and thickness of the skin at the recipient site. Evaluate for evidence of prior sun damage ( eg , keratoses ) and prior scarring . On the face, it is desirable to replace "like with like"

30. Operative Techniques Harvest of STSG:- STSG are harvested using a mechanical dermatomes which are usually powered by compressed air or electricity Manual dermatomes To harvest the skin, the donor site is put on tension by the assistant after the surface of both the dermatome and the skin has been lubricated Split-thickness grafts are commonly taken from the abdominal wall, thigh and buttocks.

31. Graft Meshing Harvested skin grafts can be used as a continuous sheet or incised to provide a meshed graft. Mesh graft:- varied expansion ratios ranging from 1.5:1 up to 9:1 Prevents accumulation of fluids Covers a larger area Has significant contractures Poor cosmesis ("alligator hide" appearance or bed net appearance )

32. Meshed STSG STSGs can be enlarged up to six times their original size The most commonly used mesh ratio is 1 : 1.5 in smaller wounds, while a mesh ratio of 1 : 3 and 1 : 6 is often needed to cover large burns Systematic enlargement with a hand-powered meshing device ( mesher ) that applies multiple slits at regular intervals

33. Operative Techniques, cont … Harvest of FTSG:- Scalpel is generally the only instrument necessary for harvesting FTSG. Infiltrate LA & adrenaline after marking. Incise & elevate the skin Trim residual adipose tissue Close donor site primarily

34. Donor site selection

35. Operative Techniques, cont …

36. Graft Inset STSG are transferred dermis-side-down to the recipient site and sutured into place with fine absorbable sutures. For small STSG, natural ( eg , fibrin) or synthetic ( eg , cyanoacrylate) glue can be used to secure a graft instead of suture Inset should be tailored to fit the size and shape of the defect in case of FTSG

37. Recipient Site Care Immobilization of the graft to the recipient bed Prevent shearing of the graft Prevent accumulation of fluid under the graft Facilitates the process of neovascularization Meshed grafts drain underlying wound fluid through the interstices, but still need to be immobilized to facilitate healing. Splints or casts help immobilize skin grafts on the extremities .

38. Recipient Site Care, cont … Bolster dressings and negative pressure wound therapy can be used for immobilization .

39. Donor Site Care The optimal dressing for STSG continue to be an area of debate Ideal donor site dressing should encourage Rapid re-epithelialization Prevent wound desiccation and at the same time allow oxygen exchange Minimizes pain Decrease risk of infection Curtails scarring Reepitelization 7-10days for thin STSG,and 14-21 for thick STSG. Primary suture repair of the donor site is performed for FTSG.

40. Skin Graft Adherence Over time, the graft will smooth out but will retain the color and consistency of the donor site Re-innervation: New nerve fibers invade the graft from both periphery and from host bed. 2-3 months fibers reach end organs and crude sensation returns. Sensation is better in FTSG than STSG .

41. Skin Graft Adherence, cont … Sweat Gland Function: Often returns in both STSG and FTSG but superior in FTSG. Are dependent on neural innervation to function, thus sweat doesn’t occur for 3 months. Hair Growth : In STSG hair follicles are damaged, as a result hair growth in them is unusual.

42. Graft Failure Can result from insufficient vascularity of the recipient site, hematoma, seroma , infection,excessive tension, mechanical shearing forces. Comorbidities including diabetes, smoking, protein or vitamin deficiencies can affect vascularity and wound healing. Medications such as steroids, immunosuppressive medications, and anticoagulants can interfere with wound healing.

43. Signs of Graft Failure Persistently white graft Dry black graft Graft mobile across recipient bed Ongoing and final absence of graft tissue

44. Referance

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