7. Healing by secondary intention and primary closure
Healing via secondary intention refers to the natural healing of the body without any intervention, e.g. apposition of wound edges. The process of healing occurs via wound contraction and the formulation of granulation tissue followed by scarring (Barrett JP, 2004).
Excision and primary closure is a simple method for the management of small burns and burns scars. The scar is excised and closed by the immediate approximation of wound edges. The key principle is that no tension should be applied to the wound edges. This is useful in areas where elasticity allows for tension-free repair; it is only indicated for small, isolated, narrow scars.
Early primary wound closure is performed within 1–5 days, and delayed primary wound closure within 6–12 days has similar advantages in reducing risk of septicaemia, mortality, morbidity, hospital stay and the cost of treatment.
7.1. Advantages of primary closure
- Improved aesthetics
- Healing occurs more rapidly
- Simple, direct method that is not technically difficult.
7.2. Disadvantages of primary closure
- Only suitable for small, isolated scars
- Tension on the wound can result in wound dehiscence or delayed wound healing
- Distortion and unsightly scars
- Scar contracture painful scars.
8. Excision and skin grafting: FTSGs and STSGs
Skin grafting refers to the acute coverage of burns rather than to reconstruction. This technique is important because early excision and skin grafting reduces the presence of necrotic and infected tissue, thus helping to reduce morbidity and mortality.
Studies have shown that early wound excision and closure (days 1–5) reduce the length of hospital stay and the costs of care. Early wound closure is associated with a reduced severity of hypertrophic scarring, joint contractures and stiffness, thus helping to promote faster rehabilitation (O’Brien, 2009).
8.1. Skin grafts
Skin grafts can be full thickness (i.e. full-thickness skin grafts [FTSGs]) or split thickness (i.e. split-thickness skin grafts [STSGs]). These are used as coverage for exposed tissues, tendons and bones, and consist of epidermis and variable amounts of dermis. Once transferred, the graft will establish a blood supply (Ong et al., 2006).
The process by which a graft adheres to the recipient site is termed take. Graft take involves vascular ingrowth into the graft from the recipient bed and fibrous tissue fixation. Eventually, a lymphatic system and neural supply will develop, but this a very slow, gradual process; however, vascularisation is rapid.
The speed of vascularisation of the graft is dependent on the graft bed, the graft itself and the conditions under which the graft is applied. Limitations of skin grafting are based on the availability of unburned donor sites, the elasticity and pliability of the skin, and the vascular supply at the graft site.
The four stages of take are adherence, plasmatic imbibition, revascularisation and remodelling. Figure 6.5 provides a summary of the four stages.
Figure 6.5. – The stages to graft healing ‘take’.