Soft tissue injury: crush injury, arterial injury, and open fractures
Fracture type
Description
0
Minimal soft tissue damage; indirect violence; simple fracture patterns (e.g., torsion fracture of the tibia in skiers)
I
Superficial abrasion or contusion caused by pressure from within; mild to moderately severe fracture configuration (e.g., pronation fracture-dislocation of the ankle joint with a soft tissue lesion over the medial malleolus)
II
Deep contaminated abrasion associated with localized skin or muscle contusion; impending compartment syndrome; severe fracture configuration (e.g., segmental bumper fracture of the tibia)
III
Extensive skin contusion or crushing injury; underlying muscle damage may be severe; subcutaneous avulsion; decompensated compartment syndrome; associated major vascular injury; severe or comminuted fracture configuration
Presentation
Classic presentation
While motor vehicle collisions, pedestrians being struck by motor vehicles, and industrial accidents are the most common causes of a crush injury, a large number of life-threatening crush injuries occur as a result of natural disasters. Injury is often clear from chief complaint and mechanism.
Arterial injuries can present broadly, from a simple hematoma to profound hemorrhagic shock. The clinical presence of “the 5 Ps” (pain, pallor, pulselessness, paresthesias, and paralysis) should be attributed to arterial injury.
Open fractures are typically obvious with significant disruption of the original anatomy and visible bony structures. The main concerns are arterial injury compromising the viability of the extremity and deep tissue and joint space contamination that can lead to long-term complications, such as osteomyelitis.
Critical presentation
The “crush syndrome” comprises the systemic manifestations that arise as a result of a crush injury once the external force is removed. The patient can develop hypovolemia, shock, compartment syndrome, lactic acidosis, or renal failure from traumatic rhabdomyolysis. Rhabdomyolysis can cause acute renal failure in up to 40% of patients with crush injuries.
Arterial injury can lead to hypotension if the hemorrhage is not addressed aggressively with source control and resuscitation with fluids.
The mangled extremity severity score (MESS) is the most widely validated classification system of the lower extremity when evaluating the severity of open fractures. Limb viability is related to vascular status, patient age, duration of ischemia, and absorbed energy. A score of 6 or less predicts limb viability while a score of 7 or higher predicts the need for amputation. MESS has high specificity but low sensitivity. As yet, there is no scoring system that reliably predicts the need for amputation.
Mangled extremity severity score (MESS)
Points
Component
Skeletal and soft tissue injury
1
Low energy (stab, simple fracture, civilian gunshot wound)
2
Medium energy (open or multiplex fractures, dislocation)
3
High energy (close-range shotgun/military gunshot wound; crush injury)
4
Very high energy (same as above plus gross contamination, soft tissue avulsion)
Electrolyte abnormalities such as low calcium and elevated serum potassium, phosphate, and uric acid that results from massive cellular damage.
Venous (or arterial) blood gas will reveal metabolic lactic acidosis.
Creatine phosphokinase (CPK), as the surrogate marker to assess the extent of muscle damage.
Urine studies will determine the presence of myoglobin indirectly. Myoglobin in the urine will be detected as “blood” on the urine dipstick but there will be no red blood cells noted on the urine analysis.
Evaluate for manifestations of hyperkalemia by obtaining an ECG. The increase in serum potassium is most severe in the first 12–36 hours after muscle injury. Initially, there may be peaked T waves and prolonged PR interval. At levels between 7–8 mEq/L, the ECG may reveal a widened QRS and flattened P waves. For potassium levels >8 mEq/L, the ECG may degenerate into a sine wave pattern (see Figure 14.1), then ventricular fibrillation, followed by cardiac arrest.
