1 / 28

Physiology of Skin Grafts

Physiology of Skin Grafts. SKIN: Physiology & Function. Epidermis: protective barrier (against mechanical damage, microbe invasion, & water loss) high regenerative capacity Producer of skin appendages (hair, nails, sweat & sebaceous glands). SKIN: Physiology & Function. Dermis:

austin
Télécharger la présentation

Physiology of Skin Grafts

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Physiology of Skin Grafts

  2. SKIN: Physiology & Function • Epidermis: • protective barrier (against mechanical damage, microbe invasion, & water loss) • high regenerative capacity • Producer of skin appendages (hair, nails, sweat & sebaceous glands)

  3. SKIN: Physiology & Function • Dermis: • mechanical strength (collagen & elastin) • Barrier to microbe invasion • Sensation (point, temp, pressure, proprioception) • Thermoregulation (vasomotor activity of blood vessels and sweat gland activity)

  4. SKIN: Physiology & Function • Immunological surveillance • Most skin is thin, hair-bearing, has sebaceous glands • Skin of palms/soles/flexor surface of digits is thick, not hair-bearing, no sebaceous glands • Vascular supply confined to dermis

  5. SKIN: Anatomy

  6. SKIN: Anatomy

  7. Skin Grafts: Classification • Full thickness skin grafts: - epidermis & full thickness of dermis • Split skin graft: • epidermis & a variable proportion of dermis • thin, intermediate or thick

  8. Skin Grafts: SSG

  9. Skin Grafts: Classification • Autografts • Isografts • Allografts • Xenografts

  10. Skin Grafts: “Process of Take” • Vascularity of donor site • Tolerance to ischaemia • Metabolic activity of the graft

  11. Skin Grafts: “Process of Take” • 4 Phases: • Fibrin adhesion • Plasmatic imbibition • Revascularization: Inosculation & capillary ingrowth • Remodelling: Revascularization & fibrous attachment in restoring normal histological architecture

  12. Skin Grafts: “Process of Take” • Plasmatic Imbibition: • Initially graft ischaemic (24 – 48 hrs) • Fibrin adhesion • Imbibition allows the graft to survive this period • ? Important for nutrition of graft • ? Stops drying out

  13. Skin Grafts: “Process of Take” • Inosculation & capillary ingrowth: • At 48 hrs • Through fibrin layer • Capillary buds from recipient bed contact graft vessels • Open channels (neo-vascularization)  pink graft

  14. Skin Grafts: “Process of Take” • Revascularization & fibrous attachment: • Connection of graft & host vessels via anastomoses (inosculation) • Formation of new vascular channels by invasion of graft (neovascularisation) • Combination of old & new vessels (revascularisation) • Fibroblast proliferation: conversion of fibrin adhesion  fibrous tissue attachment (anchorage within 4 days)

  15. Skin Grafts: “Process of Take”

  16. Skin Graft Take: Epidermis

  17. Skin Graft Take: Epidermis

  18. Skin Graft Take: Dermis • Fibrous component:

  19. Skin Graft Take: Dermis • Appendages: - sweating dependent on no. of transplanted sweat glands & degree of sympathetic reinnervation; will sweat like recipient site in FTSG only - sebaceous gland activity mostly in thicker grafts: SSG usually dry & shiny - hair grows from FTSG if well taken with no complications

  20. Skin Graft Healing • Initially white then pinkens with new blood supply • Lymphatic drainage by day 6 • Collagen replacement from day 7 to week 6 • Vascular remodelling for months

  21. Skin Graft Healing • Contraction: - shrinks immediately due to elastic recoil: – FTSG 40%; medium SSG 20%; thin SSG 10%. - secondary contracture as heals: - FTSG remains same size after above shrinkage; - SSG will contract as much as possible; - more dermis = less contraction - ? Due to myofibroblasts

  22. Skin Graft Healing • Reinnervation: • from margins to bed; • 4/52 to 2 years; • Depends on graft thickness and bed; • Uneventful healing leads to near normal 2PD; • Cold sensitivity can be a problem.

  23. Skin GraftExpansion • Based on principle that wounds reepithelialized from the periphery • Expansion provides larger areas from which epithelium can grow • Larger areas can be covered with less skin

  24. Skin GraftExpansion • Meshing - covers large area - easier to contour - fluid can drain through holes - cosmetic results less than ideal - various mesh ratio

  25. Skin Graft Survival • Meticulous technique • Atraumatic graft handling • Well vascularized bed • Haemostasis • Immobilization • No proximal constricting bandages

  26. Skin Graft Failure • Haematoma • Infection • Seroma • Mobility • Inappropriate bed • Dependency • Arterial insufficiency • Venous congestion • Lymphatic stasis • Technical – upside-down

More Related