Definitions
- Autograft = graft from one part of body to another in the same individual
- Allograft = graft from one individual to another in the same species
- Xenograft = graft from one species to another
Skin grafts
- A skin graft is an autograft
- Can be partial or full thickness depending on the amount of dermis taken
Partial-thickness skin grafts
- Contains epidermis and superficial part of dermis
- Usually taken from donor site with dermatome or Humby knife
- Donor site epithelium grows back from sweat glands and hair follicles
- Graft can be 'meshed' to increase the area that can be covered
- Excess skin can be stored in fridge and reused for up to 3 weeks
- Partial-thickness grafts can not be used on infected wounds
- Not suitable for covering bone, tendon or cartilage
- Cosmetic result is often not good
Full-thickness skin grafts
- Contains epidermis and all of dermis
- Can only be used to cover small defects
- Good cosmetic results can be obtained
- Donor site needs to be closed with primary suture or partial thickness graft
- Common donor sites include the postauricular skin and supraclavicular fossa
Skin flaps
- Classified according to blood supply
Random pattern grafts
- Receives blood supply from segmental anastomotic or axial artery
- Examples include advancement and rotation flaps
An advancement flap
A rotation flap
Axial pattern grafts
- Receives blood supply from a direct cutaneous arteries
- Examples include:
- Iliofemoral island flap supplied by superficial circumflex iliac artery
- Lateral forehead flap supplied superficial temporal artery
- Deltopectoral island flap supplied by perforating branches of internal mammary artery
- Survival of all flaps depends on it receiving an adequate blood supply
- Depend on length of flap in relationship to its base
- Blood supply can be improved by the use of 'delaying' techniques
- The flap is partially raised and replaced prior to use
- Encourages the flap to increase its blood supply through the pedicle
Tube pedicle grafts
- Frequently raised from abdomen or inner arm
- Parallel skin incisions allow tube of skin to be formed
- Skin defect is then closed
- The length of the tube should not be greater than twice the base
- Long axis of tube should parallel the direction of the cutaneous blood vessels
- Good means of delaying tissue transfer over a long distance
- Produces a good cosmetic result
Myocutaneous flaps
- In most parts of the body the skin receives its blood supply from the underlying muscle
- Muscle, fascia and overlying skin can therefore be moved as one unit
- The survives on major blood vessel supplying the muscle
- Examples include
- Latissimus dorsi flap supplied by thoracodorsal artery
- Transverse rectus abdominis supplied by superior epigastric artery
- Allow tissue transfer to poorly vascularised areas
- Bone can also be transferred for osseous reconstruction
- Flaps usually have no sensation
Free myocutaneous flaps
- Microvascular techniques allow the anastomosis of arteries and veins
- Myocutaneous flaps can therefore be detached from blood supply
- Can be transferred to other parts of body
- Examples include the free transverse rectus abdominis flap
Tissue expansion
- Skin can be gradually stretched to accommodate a greater area
- If skin loss is anticipated it is possible to expand adjacent skin prior to operation
- Tissue expanders can be placed subcutaneously in collapsed state
- Over several weeks can be inflated with saline through a subcutaneous port
- Expanded skin can be used to cover defect and tissue expander removed
Bibliography
Valencia I C, Falabella A F, Eaglstein W H. Skin grafting. Dermatol Clin
2000; 18: 521-532. |