Skin Flaps And Grafts[1].pdf

Skin Flaps And Grafts DR. ALI ABDEL KADER A S S ISTANT P ROF ESSOR OF G E NERA L S U RG ERY Introduction: Skin grafts and skin flaps are two surgical techniques that are commonly utilised by plastic surgeons when a defect cannot be closed by primary or secondary intention. The key differe...

Skin Flaps And Grafts DR. ALI ABDEL KADER A S S ISTANT P ROF ESSOR OF G E NERA L S U RG ERY Introduction: Skin grafts and skin flaps are two surgical techniques that are commonly utilised by plastic surgeons when a defect cannot be closed by primary or secondary intention. The key differences between a graft and a flap is in regards to its blood supply; a skin graft receives its blood supply from the recipient site though the vascular bed, whilst a skin flap brings its blood supply from the donor site. Skin Grafts: A skin graft has no blood supply, and therefore depends on the vascularised bed where it is placed. Skin grafts are often utilised as part of the management of extensive skin damage, such as those caused from deep burns, following large skin excision procedures, or poorly healing ulcerating lesions. Several considerations need to be made when choosing a donor site; this includes the amount of skin required, the colour and texture of the donor skin, and if hair growth is required at the recipient site. Granulation tissue developing on a skin graft wound There are two types of skin graft: Split-skin thickness skin graft (SSG) – does not contain the whole dermis Full-thickness skin graft (FTSG) – contains the whole dermis (also transplanting hair follicles) Skin grafts must heal by developing a new blood supply. They can fail (i.e. not obtain an adequate blood supply) for a number of reasons, including haematoma or seroma formation under the graft, infection (commonly Streptococcus spp.), shearing forces, an unsuitable bed, or technical error. signs of graft failure: pallor or discolouration at the graft site, evidence of localised infection, systemic features (malaise, lethargy), or even full thickness necrosis* (occurs 1-2 weeks after grafting). All skin grafts undergo contraction, either primary or secondary. Primary contraction relates to the immediate contraction or recoil of freshly harvested skin and is more pronounced in FTSG. Secondary contracture describes the process of contraction once the graft has been applied to its bed and healing is underway, and is more pronounced in SSGs. Full Thickness Skin Grafts: A full thickness skin graft contains the full thickness of the epidermis and dermis. They are commonly used to cover areas with optimal vascular availability, as they have higher energy requirements and are therefore may be more prone to graft failure. Once the graft is harvested, there is no epidermis left behind at the donor site and therefore this site must be closed using sutures. A full thickness skin graft from the left forearm on the left index finger Split Thickness Skin Grafts: A split thickness skin graft contains the full epidermis with a variable thickness of dermis, leaving dermal remnants at the donor site to allow for re- epithelization. Split thickness grafts are commonly used for skin defects that are too large for a full thickness graft. The most commonly used donor site is the thigh, however other donor sites include the forearm, torso, and lower leg.  Skin Flaps: A skin flap is where tissue is transferred from a donor site to recipient site along with its corresponding blood supply. Skin flaps are thought to provide better cosmetic results than skin grafting, as the skin tone and texture are usually better matched. Additionally, they have a reduced chance of failure in comparison to skin grafts. However, flap failure remains a potential complication of the procedure*. This can occur due to issues with either the arterial supply, presenting with signs of pallor and reduced perfusion, or venous supply, presenting with features of venous congestion.  Classification Flaps can be classified via their tissue type, blood supply, or location. Tissue Type: For tissue types, this is based on the compositions that are utilised in the flap, including cutaneous flap, fasciocutaneous flap, musculocutaneous flap, or muscle flaps. Blood Supply Axial flap – a designated fasciocutaneous artery that runs beneath the flaps longitudinal axis Random flap – no designated named artery that provides blood supply to the flap; blood supply via the subdermal plexus Pedicled (or perforator) flap – the tissue is completely raised on a named vessel from the donor site and then transferred to the recipient site; this can be as a pedicled flap or free flap. Location Subtypes When defined by location, flaps can be classified as either local, regional, or free flaps Local flaps are harvested from a contiguous site and are commonly used for facial defects, fingertip injuries, or defects on the limb. These can be further classified into: Advancement flap – The skin is moved directly forward Rotation flap – The skin is rotated around a pivot point to cover an adjacent defect Transposition flap – Moves laterally in relation to the pedicle to cover an adjacent defect ❖Regional (or pedicled) flaps are harvested from the same anatomical region but not directly adjacent. The attached skin (or pedicle) will be tunnelled under the intact tissue, or laid over intact skin forming what is known as a skin bridge, which can then detached from the donor site in a second procedure. ❖Free (or distant) flaps are harvested from a different anatomical region entirely. The tissue and named fasciocutaneous artery are separated from the donor site before being reattached at the recipient site using microsurgical techniques.  Flap Donor site Vessel Skin and subcutaneous tissue of lower abdomen, spares the rectus Deep inferior epigastric perforator (DIEP) Deep inferior epigastric artery abdominis Transverse Rectus Abdominis Myocutaneous (TRAM) Skin, subcutaneous tissue, and part of the rectus abdominus Deep inferior epigastric artery Latissimus Dorsi Myocutaneous Flap (LDMF) Skin, subcutaneous tissue, and part of the latissimus dorsi Subscapular artery Thoracodorsal artery perforator (TAP) Skin and subcutaneous tissue of lateral back, sparing the latissimus dorsi Thoracodorsal artery Skin and subcutaneous tissue of anterolateral thigh (can include vastus Anterolateral thigh (ALT) Descending branch of lateral circumflex artery lateralis muscle) Specific Examples of Common Free Flaps  Pathogenesis of flap failure: Extrinsic Factors: 1) Haematomas under the flaps 2) Wound infection 3) Systemic hypotension 4) Tension of the flaps 5) Cigarette smoking smoking Intrinsic factors: 1) Inadequate arterial inflow 2) Inadequate venous drainage 3) Arterio‐venous shunting.