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Difficulty: HardOrthopedic Surgery

A 22-year-old male is brought to the emergency department after a severe collision during a rugby match. On presentation, he is in severe pain. His vital signs are temperature 37.1°C (98.8°F), blood pressure 130/80 mmHg, heart rate 98/min, and respiratory rate 16/min. Physical examination reveals a grossly deformed left knee with a significant posterolateral prominence. The left foot is cool and pale, and both the dorsalis pedis and posterior tibial pulses are not palpable. Capillary refill is delayed. Assume that after initial interventions, the distal pulses return but remain asymmetric compared to the contralateral limb, and subsequent advanced imaging reveals a popliteal artery intimal flap. Arrange the following steps in the correct chronological order for the acute evaluation and management of this patient.

  1. 1Immediate bedside closed reduction of the knee joint
  2. 2Reassessment of distal pulses and capillary refill
  3. 3Measurement of the ankle-brachial index (ABI)
  4. 4Computed tomography angiography (CTA) of the lower extremity
  5. 5Operative exploration and vascular repair

Answer

The correct sequence is: 1) Immediate bedside closed reduction of the knee joint, 2) Reassessment of distal pulses and capillary refill, 3) Measurement of the ankle-brachial index (ABI), 4) Computed tomography angiography (CTA) of the lower extremity, 5) Operative exploration and vascular repair.
The correct chronological sequence aligns with Advanced Trauma Life Support (ATLS) and orthopedic emergency guidelines for limb-threatening injuries. A knee dislocation with an absent pulse is a true emergency necessitating immediate bedside closed reduction to unkink the popliteal artery. Once reduced, neurovascular status is immediately reassessed. Because the pulses in this scenario are asymmetric post-reduction, an ABI is measured to quantify perfusion. An abnormal ABI prompts a CTA to anatomically define the injury. Finally, the confirmed intimal flap requires operative vascular repair.

Step-by-Step Solution

1
Identify the primary emergency.
The patient has a knee dislocation with hard signs of vascular injury (absent distal pulses, cool and pale limb).
Recognizing a pulseless limb is critical, as it requires immediate mechanical intervention rather than diagnostic imaging.
2
Determine the initial intervention.
Immediate bedside closed reduction is performed to relieve traction on the popliteal vessels.
Delaying reduction to obtain X-rays or CTA in a pulseless limb drastically increases the risk of irreversible ischemic damage and amputation.
3
Determine the post-reduction evaluation algorithm.
Distal pulses must be rechecked. If they are asymmetric or if the ABI is less than 0.9, CTA is indicated.
Even if pulses return, the high incidence of popliteal artery injury (e.g., intimal tear) in knee dislocations mandates objective vascular testing (ABI) followed by CTA for abnormal results.
4
Establish definitive management.
Surgical exploration and repair is performed.
A CTA confirming an intimal flap in the setting of asymmetric pulses requires operative vascular repair to ensure long-term limb viability.

Key Concept

The acute management of a knee dislocation with vascular compromise requires immediate closed reduction to restore perfusion, followed by sequential vascular evaluation (pulse check, ABI, CTA) and definitive surgical repair if a vascular injury is confirmed.
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Topics

Orthopedic Surgery

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