﻿ Gunshot Wounds and Open Fractures - AAOS Comprehensive Orthopaedic Review

## AAOS Comprehensive Orthopaedic Review

### Chapter 49. Gunshot Wounds and Open Fractures

I. Gunshot Wounds

A. Epidemiology

1. One third to one half of US households contain firearms.

2. Two thirds of weapons are loaded and stored within reach of children.

3. Firearm-related deaths totaled 30,136 in 2003 and 69,825 in 2005.

B. Ballistics

1. Low-velocity firearms are defined as <2,000 ft/sec and include all handguns.

2. High-velocity firearms are defined as >2,000 ft/sec and include all military rifles and most hunting rifles.

3. Shotguns can inflict either high- or low-energy injuries. Their wounding potential depends on three factors.

a. Chote (shot pattern)

b. Load (size of the individual pellet)

c. Distance from target

C. Energy

1. The kinetic energy (KE) of a moving object is proportional to its mass (m) and the square of its velocity (v2) and is defined by the equation: KE = 1/2 (mv2).

2. The energy delivered by a missile to a target is dependent on three factors.

a. The energy of the missile on impact (striking energy)

b. The energy of the missile on exiting the tissue (exit energy)

c. The behavior of the missile while traversing the target (eg, tumbling, deformation, fragmentation)

D. Tissue parameters

1. The wounding potential of a bullet depends on its caliber, mass, velocity, range, composition, and design, as well as characteristics of the target tissue.

2. The degree of injury created by the missile depends on the specific gravity of the traversed tissue. The higher the specific gravity of the tissue, the greater the tissue damage.

3. A missile projectile achieves a high kinetic energy due to its high velocity.

a. The impact area is relatively small, resulting in a small area of entry.

b. A momentary vacuum is created by its resultant soft-tissue shock wave, which can draw adjacent material, such as clothing and skin, into the wound.

4. The direct passage of the missile through the target tissue defines the permanent cavity. The permanent cavity is small, and the surrounding tissues are subjected to crush.

5. A temporary cavity (cone of cavitation) is created by a stretch-type injury from the dissipation of imparted kinetic energy (ie, shock wave). It is larger than the permanent cavity; its size distinguishes high-energy from low-energy wounds.

6. Gases are compressible, whereas liquids are not.

a. Penetrating missile injuries to the chest may produce destructive patterns only along the direct path of missile.

b. Similar injuries to fluid-filled structures (eg, liver, muscle) produce considerable displacement of the incompressible liquid with shock-wave dissipation, resulting in much larger momentary cavities. This may lead to regions of destruction apparently distant to the immediate path of the missile with resultant soft-tissue compromise.

E. Clinical evaluation

1. Specific evaluation of the gunshot injury is based on the location of injury and patient presentation. A thorough physical examination must be performed to rule out the possibility of neurovascular damage.

2. Radiographic evaluation is necessary to assess for retained missile fragments, amount of fracture comminution, and the presence of other foreign bodies (eg, gravel).

3. Missile fragments often can be found distant to the site of missile entry or exit.

F. Treatment

1. Low-velocity wounds are treated based on fracture type

a. Outpatient nonsurgical treatment

i. Antibiotics (first-generation cephalosporin), tetanus toxoid, antitoxin

ii. Irrigation and debridement of the entrance and exit skin edges

b. Indications for surgical debridement

i. Retention of bullet fragments in the subarachnoid or joint space

ii. Vascular disruption

iii. Gross contamination

iv. A missile that is palpable on the palm or sole

v. Massive hematoma, severe tissue damage, compartment syndrome, or gastrointestinal contamination

c. Fractures generally are treated similar to a closed fracture.

2. High-velocity and shotgun wounds should be treated like high-energy injuries with significant soft-tissue damage

a. Administration of antibiotics (first-generation cephalosporin), tetanus toxoid, antitoxin

b. Extensive and often multiple surgical debridements

c. Fracture stabilization

d. Delayed wound closure with possible skin grafts or flaps for extensive soft-tissue loss

3. Gunshot wounds that pass through the abdomen and exit through the soft tissues with bowel contamination deserve special attention. These require debridement of the intra-abdominal and extra-abdominal missile paths, along with administration of broad-spectrum antibiotics covering gram-negative and anaerobic pathogens.

G. Complications

1. Retained missile fragments

a. These generally are well tolerated and do not warrant a specific indication for surgery.

b. Surgical exploration is necessary if symptoms develop (ie, pain, loss of function), the wound is in a superficial location (especially on the palms or soles) or in an intra-articular or subarachnoid location.

2. Foreign bodies in the wound

a. Gunshot injuries are not necessarily "sterile injuries," with contamination secondary to skin flora, clothing, and other foreign bodies that may be drawn into the wound at the time of injury.

b. Meticulous debridement and copious irrigation minimize the possibility of wound infection, abscess formation, and osteomyelitis.

3. Neurovascular damage

a. The incidence of neurovascular damage is much higher in high-velocity injuries, secondary to shockwave energy dissipation.

b. Temporary cavitation may result in traction or avulsion injuries to neurovascular structures remote from the immediate path of the missile.

4. Contamination with lead breakdown products

a. Synovial or cerebrospinal fluid is caustic to lead components of bullet-missiles, resulting in lead break-down products that may produce severe synovitis and low-grade lead poisoning.

b. Intra-articular or subarachnoid retention of missiles or missile fragments are indications for exploration and missile removal.

II. Open Fractures

A. Definition—An open fracture is a fracture that communicates with an overlying break in the skin.

B. Clinical evaluation

1. Initial assessment focuses on Airway, Breathing, Circulation, Disability, and Exposure (ABCDE).

a. Because one third of patients with open fractures have multiple injuries, evaluation for life-threatening injuries must be addressed first, followed by injuries to the head, chest, abdomen, pelvis, and spine.

b. Injuries to all four extremities must next be assessed, including a complete soft-tissue and neurovascular examination.

2. Surgical exploration of the open wound in the emergency setting is not indicated if surgical intervention is planned. Exploration risks further contamination with limited capacity to provide useful information and may precipitate further hemorrhage. However, if a surgical delay is expected, open wounds can be irrigated in the emergency department with sterile normal saline solution.

3. Compartment syndrome must be considered a possibility with all extremity fractures.

a. Pain out of proportion to the injury, pain to passive stretch of fingers or toes, a tense extremity, and decreased sensation are all clues to the diagnosis.

b. In the appropriate clinical setting, a strong suspicion based on clinical findings or if the patient is unconscious warrants monitoring of compartment pressures.

c. Compartment pressures within 30 mm Hg of the diastolic blood pressure indicate compartment syndrome and the need for emergent fasciotomy.

1. A radiographic trauma survey includes a lateral cervical spine and AP views of the chest, abdomen, and pelvis.

2. Extremity radiographs should be ordered as indicated by clinical examination.

3. Additional studies such as CT (with and without contrast), cystography, urethrography, intravenous pyelogram, and angiography are ordered as clinically indicated.

4. Angiography should be obtained based on clinical suspicion of vascular injury and the following indications.

a. Knee dislocations with an ankle-brachial index (ABI) <0.9

b. A cool, pale foot with poor distal capillary refill

c. High-energy injury in an area of compromise (eg, trifurcation of the popliteal artery)

d. Documented ABI <0.9 associated with a lower extremity injury

D. Classification of open fractures

1. Gustilo and Anderson—Based on the size of the open wound, amount of muscle contusion and soft-tissue crush, fracture pattern, amount of periosteal stripping, and vascular status of the limb. This classification has been shown to have poor interobserver reproducibility.

a. Grade I: Clean skin opening of <1 cm, usually from inside to outside with minimal muscle contusion. The fracture pattern usually is simple transverse or short oblique.

b. Grade II: A laceration >1 cm long, with extensive soft-tissue damage and minimal to moderate crushing component. The fracture pattern usually is simple transverse or short oblique with minimal comminution.

c. Grade III: Extensive soft-tissue damage, including the muscles, skin, and neurovascular structures. These are high-energy injuries with a severe crushing component.

i. IIIA: Extensive soft-tissue damage but adequate osseous coverage; there is no need for rotational or free flap coverage. The fracture pattern can be comminuted and segmental.

ii. IIIB: Extensive soft-tissue injury with periosteal stripping and bone exposure requiring soft-tissue flap closure. These injuries usually are associated with massive contamination.

iii. IIIC: Indicates a vascular injury requiring repair.

2. Tscherne—Takes into account wound size, level of contamination, and fracture mechanism.

a. Grade I: Associated with a small puncture wound without associated muscle contusion and negligible bacterial contamination. These injuries result from a low-energy mechanism of injury.

b. Grade II: Associated with a small skin laceration, minimal soft-tissue contusion, and moderate bacterial contamination. These injuries can result from a variety of mechanisms of injury.

c. Grade III: Has a large laceration with heavy bacterial contamination and extensive soft-tissue damage. These injuries are frequently associated with arterial or neural injury.

d. Grade IV: Incomplete or complete amputation with variable prognosis based on location of and nature of injury.

E. Nonsurgical treatment

1. Emergency department—occurs after the initial trauma survey and resuscitation for life-threatening injuries

 a. Control bleeding by direct pressure rather than limb tourniquets or blind clamping. b. Perform a careful clinical and radiographic examination. c. Initiate parenteral antibiotics and tetanus prophylaxis. d. Assess skin and soft-tissue damage and place a saline-soaked sterile dressing on the wound.

[

Table 1. Requirements for Tetanus Prophylaxis]

 e. Reduce and splint all fractures. f. Prepare the patient for emergent surgical debridement and osseous stabilization. Intervention within 8 hours after injury has been reported to result in a lower incidence of wound infection and osteomyelitis. However, there has been a move to delay operating on lower energy open fractures in the middle of the night and to treat the injury first thing in the morning.

2. Antibiotic coverage

a. Gustilo grades I and II open fractures usually are treated with a first-generation cephalosporin for 72 hours after each debridement.

b. Gustilo grade III open fractures are treated with a first-generation cephalosporin and an aminoglycoside.

c. Farm injuries are treated similar to grade III injuries with the addition of penicillin.

3. Tetanus prophylaxis

a. Should be initiated in the emergency room.

b. The current dose of toxoid is 0.5 mL, regardless of patient age.

c. For immune globulin, the dose is 75 U for patients younger than 5 years, 125 U for patients between 5 and 10 years, and 250 U for patients older than 10 years.

d. Both shots are administered intramuscularly, each from a different syringe and into a different site.

e. Requirements for tetanus prophylaxis are shown in Table 1.

F. Surgical treatment

1. Adequate irrigation and debridement is the most important step in open fracture management.

a. The wound should be extended proximally and distally to expose and explore the zone of injury.

b. Meticulous debridement should begin with the skin and subcutaneous fat and extended down to bone.

2. The fracture surfaces should be exposed, with re-creation of the injury mechanism.

a. Tendons, unless severely damaged or contaminated, should be preserved.

b. Bone fragments should be discarded only if they are devoid of soft-tissue attachments.

c. Extension into adjacent joints mandates exploration, irrigation, and debridement.

3. Pulsatile lavage irrigation, with or without antibiotic solution, should be performed.

4. Intraoperative cultures are considered not necessary.

5. Fasciotomy should be considered, especially in the forearm or leg.

6. Wound closure

a. Historically, traumatic wounds should not be closed. More recently, however, some trauma centers have been closing the open wound after debridement with close observation for signs or symptoms of sepsis.

b. If the wound is left open, it should be dressed with a saline-soaked gauze, synthetic dressing, a vacuum-assisted closure (VAC) sponge, or an antibiotic bead pouch.

7. Serial debridement(s) may be performed every 24 to 48 hours as necessary until there is no evidence of necrotic tissue.

G. Fracture stabilization

1. Provides protection from additional soft-tissue injury, maximum access for wound management, and maximum limb and patient mobilization.

2. The type of fracture stabilization (internal or external fixation) depends on the fracture location and degree of soft-tissue injury.

H. Soft-tissue coverage and bone grafting

1. Wound coverage is indicated once there is no further evidence of tissue necrosis.

a. Types include primary closure, split-thickness skin graft, and rotational or free muscle flap.

b. The type of soft-tissue coverage depends on the severity and location of the soft-tissue injury.

2. Bone grafting can be performed when the wound is clean, closed, and dry.

a. The timing of bone grafting after free flap coverage is controversial.

b. Some advocate bone grafting at the time of coverage; others wait until the flap has healed (normally 6 weeks).

I. Limb salvage versus amputation

1. In Gustilo grade III injuries, the choice between limb salvage and amputation is controversial.

2. Indications for immediate or early amputation

a. Nonviable limb, irreparable vascular injury, warm ischemia time of more than 8 hours, or a severe crush injury with minimal remaining viable tissue

b. Attempts at limb salvage leave the limb so severely damaged that function will be less satisfactory than that afforded by a prosthetic replacement.

c. The severely damaged limb constitutes a threat to the patient's life, especially in patients with severe, debilitating, or chronic disease.

d. The severity of the injury would demand multiple surgical procedures and prolonged reconstruction time that is incompatible with the personal, sociologic, and economic consequences the patient is willing to withstand.

e. The patient presents with severe multiple trauma in which the salvage of a marginal extremity may result in a high metabolic cost or large necrotic/inflammatory load that could precipitate pulmonary or multiple organ failure.

J. Complications

1. Infection

a. Open fractures may result in cellulitis or osteomyelitis despite aggressive serial debridements, copious lavage, appropriate antibiosis, and meticulous wound care.

b. Higher grade open fractures are at increased risk for infection.

c. Gross contamination at the time of injury is causative, although retained foreign bodies, soft-tissue compromise, and multiple-system injury also are risk factors.

2. Compartment syndrome

a. Devastating complication that can result in severe loss of function.

b. A high index of suspicion is required, with serial neurovascular examinations accompanied by compartment pressure monitoring, as needed.

c. Prompt identification of impending compartment syndrome and fascial release are essential to minimize the risk of long-term disability.

Top Testing Facts

1. The distinction between low- and high-velocity gunshot wounds is the speed of the projectile: low-velocity is <2,000 ft/sec; high-velocity is >2,000 ft/sec.

2. Shotgun blasts can inflict either high- or low-energy injuries, depending on chote (shot pattern), load (pellet size), and distance from the target.

3. Low-velocity gunshot wounds can be treated similar to a closed fracture, with antibiotics and debridement of the entrance and exit skin edges.

4. Indications for surgical debridement of low-velocity gunshot wounds include bullet fragments in the subarachnoid or joint space, vascular disruption, gross contamination, a palpable bullet fragment on the palm or sole, massive hematoma, severe tissue damage, compartment syndrome, or gastrointestinal contamination.

5. High-velocity gunshot wounds should be treated like high-energy injuries.

6. Open fractures should be treated with emergent surgical debridement and fracture stabilization.

7. Gustilo grades I and II open fractures can be treated with a first-generation cephalosporin, grade III with cephalosporin and an aminoglycoside, and farm injuries similar to grade III with the addition of penicillin.

8. Intraoperative cultures are not considered necessary for open fractures.

9. For open fractures, fracture stabilization provides protection from further soft-tissue injury.

10. For Gustilo grade III fractures, the indications for limb salvage versus amputation are controversial.

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