5.2 Burn Classification & PT Considerations
Key Takeaways
- Burns are classified by depth as superficial, superficial partial-thickness, deep partial-thickness, full-thickness, and subdermal, with healing time and scarring risk rising as depth increases.
- Adult Rule of 9s assigns 9% Total Body Surface Area (TBSA) to the head and to each arm, 18% to the anterior trunk, 18% to the posterior trunk, and 18% to each lower extremity, with 1% for the perineum.
- Anti-deformity positioning keeps the shoulder abducted near 90 degrees, elbows extended, hands intrinsic-plus, hips extended and neutral, knees extended, and ankles in neutral dorsiflexion.
- Custom compression garments are introduced once wounds are essentially closed and worn about 23 hours per day for roughly 12 to 24 months to control hypertrophic scarring.
- PTAs report any change in graft integrity, drainage character, or pain pattern to the supervising PT before progressing range of motion or compression.
Burn Depth Classification
Burn depth determines healing time, scar risk, surgical need, and how aggressively the PTA can position and stretch. The single most tested distinction is deep partial-thickness vs full-thickness, because that line decides whether the wound can re-epithelialize on its own or requires grafting.
| Depth | Structures Involved | Appearance | Pain | Healing |
|---|---|---|---|---|
| Superficial | Epidermis only | Red, dry, no blisters (classic sunburn) | Painful | 3 to 7 days, no scar |
| Superficial Partial-Thickness | Epidermis and upper (papillary) dermis | Moist, red, blanching, blisters | Very painful, hyperalgesic | About 7 to 21 days, minimal scar |
| Deep Partial-Thickness | Epidermis and deep (reticular) dermis | Mixed red and white, wet or waxy, sluggish blanching | Painful but pinprick may be reduced | 3 to 5 weeks; hypertrophic scarring likely |
| Full-Thickness | Through dermis into subcutaneous tissue | Leathery, dry, white, brown, or charred; no blanching | Insensate at center (sensory nerves destroyed) | Will not re-epithelialize from center; needs grafting |
| Subdermal | Into muscle, tendon, or bone | Charred, mummified, exposed deep structures | Insensate | Requires excision/reconstruction; possible amputation |
A classic trap: full-thickness burns can be painless at the center because the nerve endings are destroyed, yet painful at the partial-thickness borders. "No pain" never means "minor burn." A second tested cue is blanching: superficial partial-thickness burns blanch briskly and refill (capillary network intact), deep partial-thickness burns blanch sluggishly, and full-thickness burns do not blanch at all because the dermal capillary bed is destroyed. Candidates should also recognize eschar — the leathery, non-elastic dead tissue over a full-thickness burn.
Circumferential eschar around a limb or the chest can act like a tourniquet, compromising distal circulation or chest expansion; the surgical release of that constriction is an escharotomy, an emergent physician procedure the PTA must recognize as a red flag (cool, pulseless, numb distal limb) and report rather than treat.
Rule of 9s For TBSA In Adults
The Rule of 9s divides the adult body into segments of roughly 9% TBSA so burn severity and fluid needs can be estimated fast. Only deep partial-thickness and full-thickness burns are counted toward TBSA; superficial (sunburn-type) burns are excluded.
- Head and neck — 9%
- Each upper extremity — 9% (total 18%)
- Anterior trunk — 18%
- Posterior trunk — 18%
- Each lower extremity — 18% (total 36%)
- Perineum — 1%
Pediatric proportions differ: infants have a relatively larger head (about 18%) and smaller legs (about 14% each), so the Lund-Browder chart is preferred in children for accuracy. The palmar method (the patient's own palm plus fingers equals roughly 1% TBSA) estimates scattered or irregular burns. The PTA does not calculate fluids, but recognizing that a burn over about 20% TBSA is a major burn helps anticipate intensive positioning, splinting, and pulmonary care.
Anti-Deformity Positioning
Burned skin and underlying tissue contract toward the position of comfort, almost always a flexed, adducted posture. Anti-deformity positioning deliberately opposes that drift, holding tissue at lengthened end-range.
| Region | Drift Into Deformity | Anti-Deformity Position |
|---|---|---|
| Anterior neck | Flexion | Slight extension; no pillow under the head |
| Shoulder (axillary burn) | Adduction, internal rotation | Abducted near 90 degrees with slight horizontal flexion (airplane splint) |
| Elbow (antecubital burn) | Flexion | Extension in a posterior elbow splint |
| Hand (dorsal burn) | Claw deformity (MCP extension, IP flexion) | Intrinsic-plus: wrist 20-30 degrees extension, MCPs 60-70 degrees flexion, IPs extended, thumb abducted |
| Hip | Flexion, external rotation, abduction | Extension, neutral rotation, legs slightly adducted |
| Knee | Flexion | Extension in a knee immobilizer |
| Ankle | Plantarflexion (foot drop) | Neutral dorsiflexion in a foot-drop splint |
Phases And PTA Role
- Emergent/acute phase — Airway, fluid resuscitation, and positioning dominate. The PTA implements anti-deformity positioning, gentle active range of motion as ordered, and pulmonary hygiene; ranging is limited over exposed tendon.
- Intermediate/wound-care phase — Daily ranging, ambulation when permitted, and activity progression. Skin grafts are typically protected from shear and motion for about 5 to 7 days post-application before active ranging resumes; always follow the surgeon's and PT's written orders.
- Rehabilitation phase — Strengthening, scar management, return-to-function training, and patient education.
A graft-specific caution: after a lower-extremity graft, the limb is usually wrapped before dependent positioning and ambulation to protect new vasculature; sudden dependent positioning without compression can shear the graft. The exam may distinguish graft types: a split-thickness skin graft (STSG) harvests epidermis and part of the dermis and covers large areas but is fragile early; a full-thickness skin graft (FTSG) includes the entire dermis, contracts less, and gives a better cosmetic and functional result over joints.
Ranging over a fresh graft is held for the surgeon-specified protective window (commonly about 5 to 7 days) precisely because shear stress lifts the graft off its new blood supply before it "takes." Once cleared, the PTA progresses gentle active range of motion, watching the graft and donor site for blistering, separation at the edges, hematoma, or changes in drainage, and reporting any of these to the supervising PT before advancing intensity.
Compression Garments And Scar Management
Custom compression garments are fitted once wounds are essentially closed and worn about 23 hours per day for 12 to 24 months to flatten hypertrophic scars, which mature over roughly that window. Garments are removed only for bathing, skin checks, and laundering, and pressures around 20-30 mmHg are typical. Adjuncts include silicone gel sheeting, scar massage, and sustained stretch. The PTA reinforces wear schedules, inspects skin under the garment for breakdown, monitors fit as edema resolves, and reports blanching changes, drainage, or new blistering to the supervising PT.
An adult sustained deep partial-thickness burns to the entire anterior trunk and the entire right upper extremity. Using the Rule of 9s, what is the approximate Total Body Surface Area involved?
A patient with deep partial-thickness burns to the bilateral axillae and antecubital regions is positioned in bed by the nursing team with both arms adducted at the sides and elbows flexed for comfort. The PTA recognizes this is contrary to anti-deformity goals. Which positioning correction is most appropriate?