The knee x-rays exhibit a posterolateral dislocation of the left knee and associated joint effusion.
Approximately 40-50% of anterior/posterior knee dislocations can be associated with an injury of the popliteal artery, and as such, the patient should have a CT Angiogram to rule out arterial injury.
This patient went on to have a CTA of his left lower extremity, which did not reveal a popliteal arterial injury, and he was admitted under the specialist for close neurovascular monitoring of his leg.