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Zorluk: Çok zorOrthopedic Surgery

A 19-year-old female collegiate gymnast is brought to the emergency department after a severe fall during a dismount. She landed awkwardly, sustaining a hyperextension injury to her left knee. On arrival, she is in severe pain. Examination reveals a gross deformity with a prominent anterior tibia. The overlying skin is intact but tense. She has decreased sensation over the dorsum of her left foot and is unable to actively dorsiflex her left ankle. Palpation reveals absent dorsalis pedis and posterior tibial pulses on the left. The emergency physician immediately performs a closed reduction, which restores anatomical alignment. Following the reduction, the patient's pain significantly improves. Her left foot becomes warm and pink, and both the left dorsalis pedis and posterior tibial pulses are now palpable and graded as 2+ (normal). Her blood pressure is 125/75 mm Hg and heart rate is 88/min. Doppler ultrasound is used to measure systolic pressures: the left brachial pressure is 130 mm Hg, the left ankle pressure is 104 mm Hg, and the right ankle pressure is 130 mm Hg. Which of the following is the most appropriate next step in the management of this patient?

  1. Computed tomography angiography of the lower extremityCevap
  2. B
    Admission for serial physical examinations of the lower extremity
  3. C
    Immediate vascular exploration in the operating room
  4. D
    Electromyography and nerve conduction studies of the lower extremity
  5. E
    Measurement of intracompartmental pressures in the lower leg

Cevap

The most appropriate next step is computed tomography angiography of the lower extremity.
The correct answer is computed tomography angiography. This patient suffered a knee dislocation. The popliteal artery is firmly anchored proximally at the adductor hiatus and distally at the soleus arch, making it highly susceptible to traction injuries during knee dislocations. While closed reduction is the appropriate first step for a pulseless deformed knee, the return of palpable pulses does NOT exclude a significant vascular injury (such as an intimal flap). Guidelines mandate the measurement of the Ankle-Brachial Index (ABI) in all knee dislocations. An ABI less than 0.900.90 (in this case, 104/130=0.80104 / 130 = 0.80) indicates impaired perfusion and warrants immediate advanced imaging with a CTA to evaluate for a surgically repairable arterial injury. If the ABI were > 0.900.90 with normal pulses, serial observation would be appropriate.

Adım Adım Çözüm

1
Analyze the mechanism of injury and initial physical examination findings.
The patient sustained a knee dislocation (implied by gross deformity and prominent anterior tibia) with initial absent pulses.
Recognizing a knee dislocation is critical because it carries a high risk of popliteal artery injury and common peroneal nerve injury.
2
Evaluate the response to the initial intervention (closed reduction).
Pulses returned to normal (2+) and the foot is well-perfused. However, the left ankle systolic pressure is 104 mm Hg and brachial is 130 mm Hg.
Normal physical examination does not definitively rule out an intimal arterial injury that can later thrombose.
3
Calculate the Ankle-Brachial Index (ABI) for the injured extremity.
The ABI is calculated as the Ankle Systolic Pressure divided by the Brachial Systolic Pressure: 104/130=0.80104 / 130 = 0.80.
An objective measurement is required to determine the necessity of advanced imaging.
4
Determine the next step based on the ABI result.
Since the ABI is less than 0.900.90, the patient requires a computed tomography angiography (CTA).
An ABI < 0.900.90 in the setting of a knee dislocation is a 'soft sign' of vascular injury, necessitating a CTA to rule out a popliteal artery tear.

Anahtar Kavram

In patients with a knee dislocation, the return of palpable distal pulses after reduction does not rule out a vascular injury; an Ankle-Brachial Index (ABI) must be calculated, and a value < 0.900.90 mandates computed tomography angiography.
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