Epidermis
Dermis
Subcutaneous layer
Papillary
Reticular
Composition
Keratinocytes Melanocytes
Langerhan cells
Merkel cells
Collagen
Elastic fibers
Fibroblasts
Collagen
Elastic fibers
Reticular fibers
Fibroblasts
Small adipocyte clusters
Predominantly adipose tissue
Collagen
Elastin
Lymphatic vessels
Vascular supply
None
Rich in small blood vessels
Rich blood supply
Rich blood supply
Appendages
Nerve endings
Meissner’s corpuscles
Hair follicle roots
Sebaceous glands
Sweat glands
Receptors
Nails
Hair follicle roots
Ruffini corpuscles
Pacinian corpuscles
Description
Keratinized stratified squamous epithelium
Loose, areolar layer
Dense, irregular connective tissue
Also known as hypodermis, consisting mainly of loose connective tissue
Principles of Incisions
Since scarring always occurs after an incision, the ideal outcome is a minimally conspicuous, fine-lined scar. However, as the final appearance of a scar depends on several factors, predicting the outcome is complex and for an identical incision, two individuals may develop different severities of scarring.
Factors of scar formation:
Size of incision
Location of incision
Skin type
Skin tension
Patient systemic factors (e.g. obesity, malnutrition, diabetes)
Patient age
Suture technique and surgeon’s own ability
The Reconstructive Toolbox
A number of techniques form the basis of most plastic surgery, such as full-thickness or split-thickness skin grafts and local, regional, or free tissue transfers.
Traditionally, the reconstructive ladder (Fig. 22.2) was used when plastic surgeons were presented with various defects. The principle is that wound closure is first achieved by the simplest method, before ‘climbing’ to more complex methods if the former fails. It provides a basic framework, progressing from simple techniques such as wound healing by secondary intention to more complex ones such as the use of free flaps.
Fig. 22.2
The reconstructive ladder
However, the reconstructive ladder is overly simplistic, and can be replaced by the reconstructive toolbox (Fig. 22.3). The use of this toolbox ensures that the technique chosen for the patient is the most appropriate to repair the injury or defect, with the best outcome initially.
Fig. 22.3
The reconstructive toolbox
Wound Healing
Wound healing is a complex and dynamic process composed of four overlapping sequential stages: haemostasis, inflammation, proliferation and repair, and remodeling (Table 22.2).
Table 22.2
Stages of wound healing
Wound Closure
Wound closure can be achieved by primary, secondary or tertiary intention [2].
Primary Intention
Most surgical incisions heal by primary intention via use of sutures:
- 1.
Wound edges are re-approximated
- 2.
Epithelial regeneration occurs
- 3.
Minimal wound contracture and scarring
Secondary Intention
- 1.
Wound edges are not re-approximated
- 2.
More intense inflammation compared to primary intention
- 3.
Greater granulation of the wound occurs
- 4.
Followed by re-epithelialization
- 5.
More extensive wound contracture and scarring
Tertiary Intention
- 1.
Wound edges are not re-approximated immediately, but debrided and cleaned first
- 2.
Allowed to granulate for a few days before wound edges are re-approximated
Free Skin Grafts
Skin grafts are defined as a layer of epidermis, along with some or all of dermis, that is removed and translocated to another part of the body. They are commonly used for the treatment of burns and extensive wounds or after excision of skin cancers.
Skin grafts can be categorised as either split-thickness or full-thickness:
Split-Thickness Skin Graft
These consist of epidermis and a variable amount of dermis. They can be further classified as thin, intermediate or thick, and are harvested with a Humby knife or more commonly a power-driven dermatome. Epidermal elements (e.g. sweat glands and pilosebaceous follicles) remain at the donor site, allowing re-epithelialization and spontaneous healing. As such, larger split-thickness skin grafts can be harvested, and are selected for more extensive defects. Common donor sites include the lateral thigh and trunk. However depending on the circumstance, amount needed and type of defect, almost any part of the body could be a potential donor site; including scrotum, scalp and foot.
Full-Thickness Skin Graft
These consist of epidermis and all of the dermis, and are harvested with a scalpel. No epidermal appendages or elements are left, and the donor area has to be closed by sutures, limiting the size of the graft. Common donor sites include the supraclavicular area and postauricular regions, as well as flexural skin (e.g. antecubital fossa, groin).
While a full-thickness graft yields better cosmetic results and is more stable against trauma, they may not take as readily as split-thickness grafts.
Survival of Skin Grafts
After the free skin graft is temporarily detached, devascularised and transferred to its new site, take occurs; the process by which the graft is reattached and revascularised (Fig. 22.4).
Fig. 22.4
The process of graft take
The two main factors influencing graft take are graft adherence via fibrin attachment, and re-vascularisation, which are in turn determined by the characteristics of the graft bed, the graft, and conditions under which the transfer occurs [4].
Skin Flaps
Flaps differ from skin grafts in that they contain their own vascular supply – arterial, venous and capillary. The effectiveness of the blood circulation determines the flap survival. They are generally used for covering up defects with poor vascularity, reconstructing the face (eyelids, nose, cheeks) and protecting vital structures.
Skin flaps can be classified in three key ways: tissue composition, donor site location or blood supply. Each of these classification systems is outlined below.
Tissue Composition (Table 22.3)
Table 22.3
Major skin flaps categorized according to composition
Flap | Composition |
|---|---|
Cutaneous | Skin and superficial fascia |
Fasciocutaneous | Skin, superficial fascia and deep fascia |
Muscle | Muscle |
Myocutaneous | Muscle and skin overlying muscle |
Osteomyocutaneous | Muscle, skin overlying muscle and bone to which the muscle is attached |
Donor Site Location
A flap may be classified based on its proximity to the site of the primary defect, and can be described as local, regional or free.
Local
Local flaps are raised from tissue in close proximity, adjacent to the primary defect, and can be further classified as advancement, rotation, or transposition flaps (Table 22.4). However, some flaps have elements of more than one technique (See Box 22.1).
Table 22.4
Local flaps
Local flaps | |
|---|---|
Advancement | A to T |
V to Y | |
Island | |
Unilateral | |
Bilateral | |
Rotation | 0 to Z |
Karapanzic | |
Transposition | Rhomboid Zitelli bilobe |
Box 22.1 An Arrangement of All the Local Graft Images on One Page
Fig. B1.1
A to T advancement
Fig. B1.2
Island flap
Fig. B1.3
Bilateral advancement flap
Fig. B1.4
O to z rotation flap
Fig. B1.5
Rhomboid flap
Regional
Regional flaps are raised from tissue in proximity, but not adjacent to the primary defect, and can be further classified as transposition or interpolation flaps (Table 22.5). Interpolation flaps include melolabial, nasofacial and paramedian forehead.
Table 22.5
Regional flaps
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