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Difficulty: MediumTrauma and Burns

A 24-year-old man is brought to the emergency department after a severe hyperextension injury to his right knee sustained during a rugby match. He is in severe pain. Physical examination reveals gross deformity of the right knee with a prominent medial femoral condyle. The right foot is slightly cool, and the right dorsalis pedis and posterior tibial pulses are palpable but noticeably weaker than those on the left. Capillary refill is 3 seconds in the right toes. Motor and sensory functions in the right foot are intact. Arrange the following steps in the most appropriate chronological sequence for evaluating and managing this patient's limb.

  1. 1Closed reduction of the right knee joint
  2. 2Measurement of the ankle-brachial index (ABI)
  3. 3Computed tomography (CT) angiography of the right lower extremity
  4. 4Operative vascular repair

Answer

The correct sequence is: Closed reduction of the right knee joint, followed by Measurement of the ankle-brachial index (ABI), then Computed tomography (CT) angiography of the right lower extremity, and finally Operative vascular repair.
The proper sequence for managing a patient with a knee dislocation and soft signs of vascular injury (such as diminished, asymmetric pulses) begins with immediate closed reduction to relieve pressure on the popliteal artery. Following reduction, the vascular status must be objectively quantified using the ankle-brachial index (ABI). An ABI less than 0.9 indicates impaired perfusion and warrants advanced imaging with CT angiography to localize the injury. Finally, if CT angiography confirms an arterial injury, operative vascular repair is required.

Step-by-Step Solution

1
Perform immediate closed reduction of the knee joint.
Relieves mechanical tension on the popliteal artery and potentially restores distal blood flow.
Prolonged ischemia leads to irreversible neuromuscular damage; reduction is the most critical first intervention and should not be delayed by imaging.
2
Measure the ankle-brachial index (ABI).
Provides an objective, quantifiable assessment of distal perfusion.
Soft signs of vascular injury (such as asymmetric pulses or delayed capillary refill) require objective quantification. An ABI less than 0.9 is highly sensitive for significant arterial injury.
3
Obtain CT angiography of the lower extremity.
Identifies the exact location and nature of the arterial injury, such as an intimal flap, pseudoaneurysm, or occlusion.
Advanced imaging is required for operative planning when the ABI is abnormal but hard signs of ischemia (e.g., absent pulses, pulsatile bleeding) are absent.
4
Perform operative vascular repair.
Definitively restores blood flow to the distal extremity.
Confirmed popliteal artery injuries require surgical intervention, such as primary repair or a reverse saphenous vein graft.

Key Concept

Algorithm for evaluating and managing knee dislocation with suspected popliteal artery injury (soft signs of vascular compromise).
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Topics

Trauma and Burns

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