TRAUMATIC POPLITEAL ARTERY OCCLUSION FOLLOWING LOWER EXTREMITY CRUSH INJURY PRESENTING WITH ISOLATED PATELLAR DISLOCATION

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Background: While traumatic popliteal artery injury historically has a low incidence, failure to acutely recognize the vascular insult poses a significant risk of limb loss and functional impairment. Relative to penetrating trauma, blunt trauma injury to the popliteal artery is not only more common but also associated with high rates of limb amputation. Delays in diagnosing the vascular injury are a significant risk factor for limb amputation. Thus, clinical suspicion and prompt diagnosis are paramount to promote limb salvage.

Case Presentation: A 71-year-old male presented for left lower extremity pain after working underneath a vehicle which slowly rolled on top of his left leg. On exam, there was visible deformity to the left patella with diminished sensation and motor function. Left distal pulses were absent to palpation and doppler ultrasound. Radiographs confirmed an isolated lateral dislocation of the left patella. The patella was reduced at bedside with proper position confirmed on X-ray, however distal pulses remained absent on repeat ultrasound. A CT-Angiography was performed which showed complete occlusion of the left distal popliteal artery below the level of the knee. The patient was taken to the operating room for a left in-situ venous bypass. There was noted significant ecchymosis of the popliteal artery extending to the mid-thigh despite no reported trauma to the left thigh. Evaluation showed a strong pulse in the superficial femoral artery, but an absent pulse below the knee in the popliteal artery. Further evaluation revealed a clear thrombus in the popliteal artery superior to the knee. Intramuscular tearing of the gastrocnemius vein was also discovered in the superficial posterior compartment of the extremity. An in-situ bypass was utilized which resulted in restoration of distal pulses and confirmed with doppler ultrasound. The surgical team proceeded with a four-compartment fasciotomy. The patient's hospital stay included three staged washouts and debridements with eventual closure of the fasciotomy. He was discharged from the hospital after thirty-eight days to a rehabilitation facility with ability to self-ambulate with assistance within one month of discharge.

Conclusion: This patient’s presentation of a low-energy injury mechanism is unique for his isolated patellar dislocation without concomitant fracture or other associated injuries characteristically associated with a traumatic vascular injury of the popliteal artery. This serves to remind providers of the importance of complete physical examination, especially a detailed vascular assessment, in the setting of blunt trauma. Any abnormal exam findings should acutely raise suspicion for vascular injury.

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