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Introduction
  •  Epidemiologyrepresent second-leading cause of death for youth in United States
  • Pathoanatomy
    • wounding capability of a bullet directly related to its kinetic energy  
    • damage caused by
      • passage of missile
      • secondary shock wave
      • cavitation
    • exponential increase in injury with increasing velocity and efficient energy transfer
    • fractures may be caused even without direct impact 
  • Associated conditions
    • lead intoxication (plumbism) 
      • may be caused by intra-articular missile
      • systemic effects include
        • neurotoxicity
        • anemia
        • emesis
        • abdominal colic
    • GSW to hip and acetabulum are most commonly associated with bowel perforation > vascular injury > urogenital injuries 
Classification
  • Low velocity  
    • muzzle velocity <350 meters per second or < 2,000 feet per second
    • most handguns except for magnums 
    • wounds comparable to Gustillo-Anderson Type I or II
  • Intermediate velocity 
    • muzzle velocity 350-500 meters per second
    • shotgun blasts
      • highly variable depending on distance from target
      • can reflect wounding potential of high velocity firearms from close range (less than 21 feet) or multiple low velocity weapons
      • wound contamination/infection with close range injuries due to shotgun wadding
      • wounding potential depends on 3 factors
        • shot pattern
        • load (size of individual pellet)
        • distance from target
  • High velocity 
    • muzzle velocity >600 meters per second or >2,000 feet per second
    • military (assault) and hunting rifles
    • wounds comparable to Gustillo-Anderson Type III regardless of size
    • high risk of infection
      • secondary to wide zone of injury and devitalized tissue
Presentation
  • Symptoms
    • pain, deformity
  • Physical exam
    • perform careful neurovascular exam
    • clinical suspicion for compartment syndrome
      • secondary to increased muscle edema from higher velocity wounds
    • examine and document all associated wounds 
      • massive bone and soft tissue injuries occur even with low velocity weapons  
Evaluation
  • Radiographs
    • obtain to identify bone involvement and/or fracture pattern 
  • CT scan
    • identify potential intra-articular missile 
    • detect hollow viscus injury that may communicate with fracture
      • high index of suspicion for pelvis or spine fractures given increased risk of associated bowel injury
Treatment General
  • Nonoperative
    • local wound care
      • indications
        • low velocity GSW with no bone involvement and clean wound edges
    • local wound care, tetanus +/- short course of oral antibiotics   
      • indications
        • low-velocity injury with no bone involvement or non-operative fractures
      • technique
        • primary closure contraindicated
        • antibiotic use controversial but currently recommended if wound appears contaminated
  • Operative
    • treatment of other non-orthopedic injuries
      • for trans-abdominal trajectories, laparotomy takes precedence over arthrotomy 
    • ORIF/external fixation
      • indications
        • unstable/operative fracture pattern in low-velocity gunshot injury
      • technique
        • treatment dictated by fracture characteristics similar to closed fracture without gunshot wound
        • stabilize extremity with associated vascular or nerve injuries   
        • stabilize soft tissues in high velocity/high energy gunshot injuries  
          • grossly contaminated/devitalized wounds managed with aggressive debridement per open fracture protocol
    • arthrotomy
      • indications
        • intra-articular missile
          • may lead to local inflammation, arthritis and lead intoxication (plumbism) 
        • transabdominal GSW   
GSW to Hand/Foot
  • Nonoperative
    • antibiotics
      • indications
        • gross contamination
        • joint penetration
        • extent of contamination unclear
  • Operative
    • surgical debridement +/- ORIF/external fixation
      • indications
        • articular involvement
        • unstable fractures
        • presentation 8 or more hours after injury
        • tendon involvement
        • superficial fragments in the palm or sole
GSW to Femur
  • Operative
    • intramedullary nailing 
      • indications
        • diaphyseal femur fracture secondary to low-velocity gunshot wound  
        • superficial wound debridement and immediate reamed nailing
        • similar union and infection rates to closed injuries
    • external fixation
      • indications
        • high-velocity gunshot wounds or close range shotgun blasts
        • stabilize soft tissues and debride aggressively
        • associated vascular injury
        • temporize extremity until amenable to intramedullary nailing
GSW to Spine
  • Nonoperative
    • broad spectrum IV antibiotics for 7-14 days 
      • indications
        • gunshot wounds to the spine with associated perforated viscus  
          • bullets which pass through the alimentary canal and cause spinal cord injuries do not require surgical removal of the bullet
  • Operative
    • surgical decompression and bullet fragment removal
      • indications 
        • when a neurologic deficit is present that correlates with radiographic findings of neurologic compression 
          • a retained bullet fragment within the spinal canal in patients with incomplete motor deficits is a relative indication for surgical excision of the fragment 
 

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Questions (5)

(OBQ13.6) A ballistics expert examines the effects of bullets on tissues. He defines a "penetrating missile" as one that delivers an entrance wound but no exit wound, and a "perforating missile" as one that possesses both entrance and exit wounds. He also defines bullet "yaw" as the tumble of a bullet or its tendency to turn sideways in flight. A diagram of bullet yaw is seen in Figure A. Which of the following scenarios leads to the greatest transfer of kinetic energy to tissues? Review Topic

QID:4641
FIGURES:
1

Penetrating missile with mass "2m", velocity "v", yaw of 90 degrees at the point of impact

13%

(216/1613)

2

Perforating missile with mass "m", velocity "2v", yaw of 0 degrees at the point of impact

5%

(86/1613)

3

Penetrating missile with mass "m", velocity "2v", yaw of 90 degrees at the point of impact

57%

(922/1613)

4

Perforating missile with mass "m", velocity "2v", yaw of 90 degrees at the point of impact

21%

(331/1613)

5

Penetrating missile with mass "2m", velocity "v", yaw of 0 degrees at the point of impact

3%

(44/1613)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

A penetrating (but not perforating) missile with highest velocity (2v) and largest yaw (90 degrees, or sideways travel) leads to greatest transfer of kinetic energy.

The kinetic energy (E) of a bullet is proportional to its mass (m), and velocity (v) squared. A bullet of mass m traveling at 2v will have greater E than one of mass 2m traveling at v. Maximum energy transfer is achieved with yaw of 90 degrees (sideways). Yaw is decreased with longer distances of bullet travel, allowing a bullet to strike its target nose-on. Penetrating (non-exiting) missiles deliver all their contained kinetic energy, while perforating (exiting) missiles transfer significantly less energy to tissues

Bartlett et al. reviewed ballistics and gunshot injuries. They state that energy transfer depends on 6 factors including: (1) amount of kinetic energy at impact, (2) stability and entrance profile (yaw), (3) caliber, construction and configuration of the bullet, (4) distance and path traveled within the body (penetrating vs perforating), (5) biological characteristics of tissues impacted, and (6) mechanism of tissue disruption (stretching, tearing, crushing).

Figure A illustrates the concept of bullet yaw. Illustration A shows blocks of gelatin perforated by similar caliber missiles at different velocities (A, 1,000fps; B, 2,800 fps), with arrows indicating missile tracks.

Incorrect Answers:
Answers 1, 2, 4, 5: These scenarios do not lead to the greatest transfer of kinetic energy to tissues.

ILLUSTRATIONS:

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(OBQ12.193) A 24-year-old male presents after being shot in the lower back. Radiographs and advanced imaging show that the bullet traversed the paraspinal musculature, entered the pelvis below the pelvic brim, and is currently lodged in the ilium. No intra-articular involvement was noted, and the bony injury is stable. No occult blood is noted on the rectal examination. The police report indicates that the bullet was fired from a low-velocity weapon. Which of the following is the most important treatment for this patient assuming he is hemodynamically stable? Review Topic

QID:4553
1

Immediate exploratory laparotomy and bullet removal

4%

(132/3512)

2

Bullet removal followed by surgical stabilization of the ilium

1%

(32/3512)

3

Immediate surgical debridement of the bullet tract and delayed closure of the soft tissue wound

6%

(212/3512)

4

Empiric antibiotic therapy and observation

86%

(3014/3512)

5

Sigmoidoscopy

3%

(98/3512)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

Based on the clinical presentation, this patient should be treated initially with empiric antibiotic therapy and observation.

The available literature shows that transabdominal GSW with intra-articular contamination should be urgently débrided and irrigated; extra-articular transabdominal GSW with stable fracture patterns may be managed with observation and empiric antibiotics. Bullets lodged in intra-articular locations should be removed, but retained bullets in other anatomic locations do not necessarily warrant removal.

Watters et al. retrospectively collected Information regarding surgical débridement of pelvis low velocity gunshot wounds, retained foreign bodies, and/or concomitant gastrointestinal (GI) injury was analyzed for relationships of such events to infection rate in 56 patients. The authors found that there was no increased incidence of infection in the absence of aggressive surgical débridement of pelvis gunshot wounds. The study also demonstrated that retained bullets and bullet fragments did not increase the risk of infection, even after penetrating the GI tract organs.

Zura et al. completed a review article on the treatment of gunshot wounds to the hip and pelvis. The authors state that antibiotic treatment usually is indicated for patients with gunshot wounds to the pelvis, but is controversial in patients with low-energy wounds. Furthermore they state that fractures are treated based on their stability and wound care should be determined by the personality of the injury, and not solely based on the velocity of the missile.

Miller et al. completed a recent review article on transabdominal gunshot wounds to the hip and pelvis. They state that extra-articular transabdominal GSW with stable fracture patterns may be managed with observation and empiric antibiotics.

Incorrect Answers:
Answer 1: Immediate exploratory laparotomy would be indicated in the setting of persistent hemodynamic instability or positive peritoneal signs.
Answer 2: There is no evidence that bullet removal is necessary when it is in an extra-articular location. Furthermore the bony injury is stable, and does not warrant fixation.
Answer 3: Immediate surgical debridement is not necessary without intra-articular involvement or severe soft tissue injury.
Answer 5: Sigmoidoscopy would be necessary if occult blood was noted on rectal examination.


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(SBQ06.2) A 21-year-old male presents to the emergency department after sustaining a gun shot wound to his abdomen. Subsequent radiographs reveal a bullet in the L2 vertebral body. Physical exam shows no neurologic deficits. He undergoes emergent laparotomy and is found to have a small bowel laceration. What would be the preferred treatment following his exploratory laparotomy and small bowel repair? Review Topic

QID:1687
1

Intravenous antibiotic coverage for Gram negative bacteria for 7 days

17%

(296/1706)

2

Surgical decompression and bullet fragment removal

4%

(61/1706)

3

Observation

6%

(104/1706)

4

Broad-spectrum oral antibiotic coverage for 7 days

6%

(102/1706)

5

Broad-spectrum intravenous antibiotic coverage for 7 days

67%

(1138/1706)

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

The clinical presentation is consistent with a GSW with bowel perforation and a retained bullet in the vertebral body. Because the patient is neurologically intact broad-spectrum intravenous antibiotic coverage for 7 days is the most appropriate treatment.

Gunshot wounds to the spine present relatively little risk of infection in most cases. When there has been an injury to the small bowel, the risk of infection can be minimized with a 7-day course of broad-spectrum antibiotics. Indications for surgery include when a neurological deficit is present that correlates with imaging findings of neurological compression by the missile, or when the missile is in contact with the CSF posing a risk for metal toxicity.

Roffi et al performed a Level 4 study of 42 patients that sustained a gunshot wound that perforated the stomach or bowel and then entered the spinal column. They found that an extended regimen of broad spectrum antibiotics combined with bedrest appeared to significantly reduce the risk of spinal or paraspinal infection, whereas early bullet removal did not significantly prevent the occurrence of infection.

Velmahoos et al performed a Level 4 study including 24 patients that sustained a gunshot wound to the spine with associated colonic injury. They found that the incidence of sepsis was 8.4% (compared to 5% in non-bowel injuries) and concluded that retainment of the bullet did not increase the rate of sepsis.

Incorrect Answers:
Answer 1: The patient needs coverage for both Gram+ and Gram- organisms.
Answer 2: There are no indications for surgery at this point.
Answer 3: Antibiotics are indicated to decrease the risk of infection.
Answer 4: Intravenous antibiotic has been found to be more effective than oral antiobiotics.


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(OBQ06.91) What is the most appropriate treatment for a 17-year-old boy who sustained a gunshot wound to his forearm from a handgun with a muzzle-velocity of 1000 feet/second if he is neurovascularly intact and radiographs reveal no fracture? Review Topic

QID:202
1

Irrigation and local wound care in the emergency department followed by 3 days of oral antibiotics

78%

(331/426)

2

Emergent irrigation and debridement in the operating room with vacuum-assisted wound closure

3%

(11/426)

3

Emergent irrigation and debridement in the operating room with 7 days of intravenous antibiotics

11%

(45/426)

4

Wound closure in the emergency department with follow-up wound check in 1 week

6%

(24/426)

5

Exploration and removal of all bullet fragments in the emergency department and 10 day course of oral antibiotics

3%

(13/426)

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

The question refers to appropriate management of a gunshot wound to the forearm. The first question that must be answered when evaluating gun shot injuries is whether the gunshot is low velocity or high velocity. Low-velocity wounds are less severe, are more common in the civilian population, and are typically attributed to bullets with muzzle velocities below 1,000 to 2,000 feet per second. Tissue damage is usually more substantial with higher-velocity (greater than 2,000 to 3,000 fps) military and hunting weapons. In this question, a muzzle velocity of 1,000 ft/sec is provided. Low velocity injuries with stable, non-operative fractures can be treated with local wound care and oral antibiotics.

The two referenced articles offer guidance for treating low-velocity gunshot injuries with stable, non-operative fracture patterns. The first article by Geissler et al is a retrospective study comparing 25 patients that prospectively received local irrigation and debridement, tetanus prophylaxis and a long acting cephalosporin intramuscularly to a random retrospective sample of 25 patients with similar ballistic-induced fractures and wounds managed by local debridement and 48h of intravenous antibiotics. One infection occurred in each group, requiring further therapy. It was concluded that patients with low-velocity gunshot induced fractures can be managed without the use of short-term intravenous antibiotics with no increased risk of infection.

In the second study, Dickey et al evaluated the efficacy of an outpatient management protocol for patients with a gunshot-induced fracture with a stable, non-operative configuration. 41 patients with a grade I or II open, non-operative fracture secondary to a low-velocity bullet were treated with 1gm of cefazolin administered in the emergency room and a 7-day course of oral cephalexin. No patient developed a deep infection. Thus, local I&D, tetanus, and oral antibiotics for 2-3 days is adequate for low velocity gunshot wounds.


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(OBQ05.233) A 24-year-old man who sustained a gunshot wound to the abdomen ten hours earlier was brought to the emergency department. On physical examination he was found to have 4 of 5 weakness in his bilateral lower extremities. Radiographs are shown in Figure A. Computed tomography of the lumbar spine showed retained missile in the vertebral body and paraspinal soft tissues, but not within the spinal canal. His FAST was positive and he underwent an emergent exploratory laparotomy where an injury to the cecum was identified and treated. Management should now include which of the following? Review Topic

QID:1119
FIGURES:
1

Bullet fragment removal from a transabdominal approach

2%

(7/424)

2

Bullet fragment removal from a retroperitoneal approach

4%

(16/424)

3

Broad-spectrum oral antibiotics for 3-5 days

11%

(47/424)

4

Broad-spectrum intravenous antibiotics for 7-14 days

75%

(320/424)

5

IV methylprednisolone at 5.4mg/kg/h for 48 hours

8%

(33/424)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

The patient in the scenario has a GSW to the lumbar spine with neurologic deficits but without a retained missile in the spinal canal. In patients with visceral injury, the treatment is broad-spectrum antibiotic coverage for 7 days.

Kumar et al reviewed 33 patients with GSW to the spine and associated visceral injuries. They concluded that 7 days of antibiotic treatment targeted at colonic flora is the treatment of choice.

Roffi et al reviewed 51 low-velocity GSW that perforated the viscus prior to the spine. They concluded that broad spectrum antibiotics combined with bedrest significantly reduced the risk of spinal or paraspinal infections. Furthermore, bullet removal had no effect on infection rates.

Velmahos et al followed 153 GSW to the spine for 28 months. While rates of sepsis were higher in the lumbar spine than cervical and thoracic spine, they concluded that retained bullets do not increase the likelihood of septic complications.

Incorrect Answers:
Answer 1 & 2: Indications for surgery with a GSW to the lumbar spine include 1) spinal instability 2) a neurologic deficit is present that correlates with radiographic findings of neurologic compression by the missile. 3) Lead missile is in contact with the cerebrospinal fluid (CSF). This patient does not have any of these criteria.
Answer 5: GSWs are a contraindication for spinal dose steroids.


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