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–
2.2m2.
• The skin is 0.5–4.0mm thick and covers the entire external surface of the
body
• Has three 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 veins
• 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
• Designing skin flap dimensions.
12
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
 Plasma 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
 Metabolism within the graft becomes anaerobic and metabolic demands of the graft
also fall
 Serum absorbed from wound bed serves as temporary nourishment for the

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.Reperfusion 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.

24. 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.

25. 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 .

26. 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

27. Preoperative Preparation
Patient Optimization
Recipient Site Preparation
Donor Site Selection

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

29. Recipient Site Preparation
• Must be well vascularized.
• Free of all necrotic / ischemic tissue, cellulitis, purulent drainage and
significant edema.
• Hemostasis
• Low bacterial count(<105 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

30. 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"

31. 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.

32. 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)

33. 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
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34. 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

35. Donor site selection

36. Operative Techniques, cont…

37. 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

38. 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.

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

40. 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.

41. 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.

42. 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.

43. 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.

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

45. Referance