Operative Management of Radiation and Chemical Burns of the Hand

INTRODUCTION TO NON-THERMAL HAND BURNS

Non-thermal burns of the upper extremity, specifically radiation and chemical injuries, represent a complex subset of hand trauma requiring specialized knowledge of pathophysiology, emergency neutralization, and reconstructive surgery. Unlike thermal burns, which deliver an immediate and finite insult, radiation and chemical burns often exhibit a progressive pattern of tissue destruction. Chemical agents may continue to cause liquefactive or coagulative necrosis until definitively neutralized, while radiation injuries induce chronic, irreversible microvascular damage that can culminate in malignant transformation decades after the initial exposure.

For the reconstructive hand surgeon, managing these injuries demands a multidisciplinary approach, integrating acute toxicological management, aggressive surgical debridement, complex soft-tissue resurfacing, and rigorous postoperative rehabilitation to preserve hand function and prevent amputation.

RADIATION BURNS OF THE HAND

Pathophysiology and Clinical Presentation

Radiation burns (radiodermatitis) of the hand are historically associated with occupational exposure, particularly among orthopedic surgeons, interventional cardiologists, and radiologists who routinely utilize fluoroscopy or hold roentgen cassettes without adequate lead shielding. The dorsum of the left hand is the most frequently affected site due to its proximity to the primary radiation beam during right-handed instrumentation.

The pathophysiology of radiation injury is characterized by progressive endarteritis obliterans, cellular DNA damage, and depletion of the basal keratinocyte layer. This results in a profound localized ischemia and an inability of the skin to regenerate.

Clinically, the progression of radiation dermatitis is insidious:
* Acute Phase (Weeks post-exposure): Characterized by intense itching, erythema, edema, and blistering.
* Chronic Phase (Months to Years): The skin becomes pale, dry, atrophic, and deeply wrinkled. Telangiectasias and scattered hyperkeratotic plaques (radiation keratoses) develop. The fingernails frequently split longitudinally and become dystrophic.
* Late Complications: As microvascular compromise worsens, minor trauma can precipitate painful, non-healing ischemic ulcers. The pain is often severe, intractable, and may require narcotic analgesia.

Surgical Warning: Chronic radiation dermatitis is a pre-malignant condition. The development of multiple squamous cell carcinomas (SCC) within the irradiated field is common and can lead to deep ulceration, invasion of extensor tendons, and metastasis. Any new ulceration or rapidly growing hyperkeratotic lesion in an irradiated hand must be biopsied immediately.

Indications for Surgical Intervention

Surgical resurfacing of the hand is indicated when conservative measures fail and the patient presents with:
1. Intractable pain secondary to ischemic ulceration.
2. Recurrent breakdown of atrophic tissue.
3. Biopsy-proven malignant transformation (Squamous Cell Carcinoma or Basal Cell Carcinoma).
4. Severe functional limitation due to skin contracture.

Surgical Technique: Excision and Resurfacing

The fundamental principle of treating chronic radiation burns is the complete excision of the irradiated field, followed by importation of healthy, well-vascularized tissue.

1. Patient Positioning and Preparation

• The patient is positioned supine with the affected arm extended on a radiolucent hand table.
• A pneumatic tourniquet is applied to the proximal arm. Exsanguination is performed carefully, avoiding pressure over ulcerated or malignant areas.
• Prophylactic intravenous antibiotics (e.g., a first-generation cephalosporin) are administered.

2. Surgical Approach and Excision

• Margin Delineation: The area of excision must be generous. Because radiation induces a "field cancerization" effect, leaving questionably involved skin will inevitably lead to recurrent ulceration or malignancy at the graft margins.
• Standard Resection: Usually, all dorsal skin from the radiocarpal joint distally to the proximal interphalangeal (PIP) joints must be excised en bloc.
• Depth of Excision: Dissection is carried down to healthy, un-irradiated tissue. On the dorsum of the hand, this typically means excising down to the paratenon of the extensor tendons.
• Preservation of Structures: Meticulous care is taken to preserve the paratenon, as skin grafts will not take on bare tendon or bone. If the paratenon is destroyed by radiation or tumor invasion, the extensor tendons must be excised, or a vascularized flap (e.g., pedicled groin flap, reverse radial forearm flap, or free anterolateral thigh flap) must be utilized instead of a skin graft.

3. Soft Tissue Reconstruction

• Split-Thickness Skin Grafting (STSG): If a healthy paratenon bed is achieved, a medium-to-thick STSG (0.014–0.018 inches) is harvested, typically from the ipsilateral anterior thigh.
• Application: The graft is meshed (usually 1.5:1) to prevent hematoma accumulation but is applied unexpanded to optimize cosmetic and functional outcomes. It is secured with absorbable sutures or surgical staples.
• Bolster Dressing: A non-adherent layer (e.g., Xeroform) is applied, followed by a tie-over bolster dressing using fluffed gauze or a negative pressure wound therapy (NPWT) device set to -75 mmHg to ensure absolute graft-to-bed apposition.

4. Management of Malignant Changes

If deep invasion of squamous cell carcinoma is present, involving the extensor mechanism, joint capsules, or bone, wide local excision may necessitate ray amputation or even proximal amputation of the hand to achieve negative oncologic margins.

CHEMICAL BURNS OF THE HAND

Pathophysiology and Classification

Chemical burns to the hand typically result from industrial spills, domestic splashing, or accidental immersion. The severity of a chemical burn is dictated by the agent's concentration, volume, duration of contact, and mechanism of action.

Chemical agents are broadly classified into acids and alkalis, each with distinct pathophysiological mechanisms:
* Acid Burns (e.g., Sulfuric Acid, Hydrochloric Acid): Acids cause coagulative necrosis. The hydrogen ions desiccate epithelial cells, precipitating tissue proteins to form a thick, leathery eschar. This eschar acts as a physical barrier, limiting further penetration of the acid. Consequently, acid burns tend to be self-limiting once the agent is neutralized by the tissue.
* Alkali Burns (e.g., Sodium Hydroxide, Lye, Cement): Alkalis cause liquefactive necrosis. Hydroxyl ions saponify cell membrane lipids and denature proteins, creating a soluble, gelatinous slough. Because no protective eschar is formed, alkalis continue to penetrate deeply into the subcutaneous tissues, tendons, and neurovascular bundles for days if not aggressively neutralized.

General Emergency Management

The prognosis of a chemical burn is directly proportional to the speed and efficacy of initial decontamination.

Clinical Pearl: The universal initial treatment for almost all chemical burns is immediate, copious, and prolonged water lavage. Lavage dilutes the agent, washes it away from the skin surface, and dissipates the exothermic heat generated by chemical reactions.

• Protocol: Lavage should begin at the scene of injury and continue for a minimum of 20 to 30 minutes.
• Goal: The objective is to return the skin pH to a near-neutral level (pH 7.0). Litmus paper can be used to test the wound bed.
• Exceptions: Prolonged lavage (up to 2 hours) may be required for severe alkali burns due to their deep tissue penetration.

Agent-Specific Management Protocols

Certain chemicals possess unique toxicological properties that contraindicate standard water lavage or require specific antidotes (Table 1).

1. Hydrofluoric Acid (HF)

Found in rust removers, glass etching solutions, and heavy-duty cleaners, HF is highly deceptive. While it is a weak acid, the fluoride ion is highly lipophilic and penetrates deeply into tissues. Once inside, it aggressively binds to intracellular calcium and magnesium, causing profound local tissue death, decalcification of bone, and potentially fatal systemic hypocalcemia and ventricular arrhythmias.
* Presentation: Disproportionately severe, unrelenting pain with minimal initial surface skin changes.
* Treatment:
* Initial water lavage.
* Topical: Application of 2.5% calcium gluconate gel. The gel is massaged into the skin until pain subsides.
* Infiltration: If pain persists, 10% calcium gluconate or magnesium sulfate is injected subcutaneously directly into and beneath the burn lesions (0.5 mL per square centimeter).
* Intra-arterial Infusion: For severe digital burns with persistent pain, intra-arterial infusion of calcium is indicated to deliver the antidote directly to the microcirculation. A catheter is placed in the radial or brachial artery, and a solution of 10 mL of 10% calcium gluconate mixed in 40 mL of D5W is infused over 4 hours.

2. Elemental Metals (Lithium, Potassium, Sodium)

• Pathophysiology: These elemental metals react violently and exothermically when exposed to water, causing severe thermal and chemical burns.
• Treatment: DO NOT USE WATER. The initial management requires covering the area with mineral oil to isolate the metal from ambient moisture. The embedded particles must then be meticulously removed with forceps. Only after all gross particles are removed can water irrigation be safely utilized.

3. Phenol (Carbolic Acid)

• Pathophysiology: Phenol is an aromatic hydrocarbon used in industrial solvents. It is highly lipophilic, causes severe coagulative necrosis, and is rapidly absorbed systemically, potentially leading to renal and hepatic failure.
• Treatment: Phenol is not water-soluble. Standard water lavage is ineffective and may spread the agent. The area must be wiped with a lipophilic solvent such as polyethylene glycol (PEG), glycerol, or isopropyl alcohol.

4. White Phosphorus

• Pathophysiology: Used in military munitions and fireworks, white phosphorus ignites spontaneously upon exposure to air and continues to burn until deprived of oxygen.
• Treatment: The hand must be immediately submerged in water to extinguish the flames. While submerged, the wounds are irrigated with a 1% to 3% copper sulfate solution. This chemical reaction coats the phosphorus particles in black cupric phosphide, impeding further oxidation and allowing the surgeon to identify and mechanically debride the particles under water.

Surgical Management of Deep Chemical Burns

Significant chemical burns, particularly those presenting late or involving deep liquefactive necrosis from alkalis, require formal surgical intervention.

1. Vascular Assessment and Decompression

Circumferential chemical burns of the hand or digits can lead to a tourniquet effect as edema accumulates beneath an inelastic eschar.
* Monitoring: The hand must be elevated. Digital circulation is monitored continuously using Doppler ultrasound probes and digital pulse oximetry.
* Escharotomy/Fasciotomy: If circulatory compromise is detected (loss of Doppler signals, delayed capillary refill, intrinsic muscle compartment firmness), immediate decompression is indicated. Mid-axial incisions are made along the digits, avoiding the neurovascular bundles. Dorsal hand escharotomies are performed over the intermetacarpal spaces.

2. Debridement and Coverage

• Tangential Excision: Once the chemical is fully neutralized and the patient is stabilized, early tangential excision of necrotic tissue is performed. The eschar is shaved sequentially until punctate bleeding from healthy dermis or subcutaneous tissue is encountered.
• Reconstruction:
  • Superficial partial-thickness burns may heal by secondary intention with topical antimicrobials (e.g., silver sulfadiazine) and non-adherent dressings.
  • Deep partial-thickness and full-thickness burns require immediate coverage. Depending on the depth of the defect and exposure of vital structures (tendons, nerves, bone), reconstruction may involve STSGs, full-thickness skin grafts (FTSGs), local pedicle flaps (e.g., cross-finger flaps), or free tissue transfer.

POSTOPERATIVE PROTOCOL AND REHABILITATION

The ultimate success of surgical intervention for both radiation and chemical burns relies heavily on a rigorous, specialized hand therapy program.

Immobilization Phase (Days 0–5)

• Following skin grafting, the hand is immobilized in a bulky dressing and a volar orthosis.
• The hand is placed in the "safe position" (James position): wrist extended 20–30 degrees, metacarpophalangeal (MCP) joints flexed 70–90 degrees, and interphalangeal (IP) joints in full extension. This prevents collateral ligament contracture and volar plate shortening.
• Strict elevation is maintained to minimize edema, which can compromise graft take and exacerbate stiffness.

Mobilization Phase (Days 5–14)

• The bolster dressing is removed at day 5 to 7 to inspect graft take.
• If the graft is stable, gentle active range of motion (AROM) exercises are initiated under the supervision of an occupational/hand therapist.
• Passive range of motion (PROM) is generally avoided initially to prevent shearing forces on the newly adherent graft.
• Between exercise sessions, the hand is returned to the resting splint.

Scar Management and Strengthening (Weeks 3+)

• Once the wounds are fully epithelialized, aggressive scar management begins. This includes scar massage, silicone gel sheeting, and custom-fitted compressive garments (e.g., Isotoner gloves) to prevent hypertrophic scarring and contractures.
• Dynamic or static progressive splinting may be required if joint contractures begin to develop.
• Strengthening exercises (grip and pinch strength) are gradually introduced as tolerated.

Clinical Pearl: Recovery from complex hand burns is a marathon, not a sprint. Prompt surgical excision of necrotic or irradiated tissue, combined with early, aggressive hand therapy, provides the highest probability of restoring a functional, pain-free upper extremity.