Plastic Surgery: Wound Healing, Grafts, Flaps and Burns
Plastic Surgery tests wound healing, skin cover, burns, hand injuries and reconstruction. The MCQ emphasises the difference between grafts and flaps and time-critical management of burns and hand trauma.
Core rules
- Wound healing: haemostasis, inflammation, proliferation and remodelling. Epithelialisation, contraction and scar maturation continue for 12 to 18 months.
- Skin graft: a split-thickness graft survives by plasmatic imbibition, inosculation and revascularisation. It needs a vascular bed and fails on bare bone or tendon without periosteum or peritenon. A full-thickness graft contracts less but needs a larger donor site.
- Flap: axial flaps have a named blood supply; random flaps depend on the subdermal plexus. Venous congestion causes a dark flap with brisk dark bleeding; arterial insufficiency causes pallor and slow capillary refill.
- Burns: the Parkland formula is 4 mL/kg/% total body surface area of crystalloid in 24 hours, with half given in the first 8 hours from the time of burn. Titrate to urine output of 0.5 to 1 mL/kg/hour in adults. Escharotomy is required for circumferential full-thickness burns or compartment syndrome.
- Inhalational injury: stridor, hoarseness, soot in the mouth or singed nasal hairs mandate early intubation.
- Hand trauma: flexor tendon repair uses a core suture; nerve injuries require prompt repair; compartment syndrome presents with pain on passive stretch and a tense compartment, requiring fasciotomy.
- Cleft lip: the rule of 10 is 10 weeks of age, 10 lb weight and 10 g/dL haemoglobin; cleft palate repair is usually at 9 to 12 months.
Worked example
A 70 kg man has a 30% total body surface area full-thickness flame burn and arrives 2 hours after injury. Parkland calculation is 4 × 70 × 30 = 8400 mL in 24 hours. Half, 4200 mL, is due in the first 8 hours from injury; because 2 hours have elapsed, 3150 mL remains over the next 6 hours.
Reasoning: the formula estimates starting fluid, but urine output and haemodynamics guide ongoing resuscitation. The burn time, not the arrival time, starts the clock.
Traps
- Burn depth is often underestimated; full-thickness burns are pale, leathery and insensate.
- Antibiotics are not routine for burns without infection.
- A graft placed on an infected bed will fail.
- Compartment syndrome in the hand can occur after seemingly minor injuries.