Popliteal Artery Pseudoaneurysm After Isolated Hyperextension of the Knee

We report an unusual case of a traumatic pseudoaneurysm of the popliteal artery after an isolated blunt hyperextension injury to the knee. A 56-year-old man presented with a 1-month history of left knee pain that occurred after a fall onto his buttocks with hyperextension of the knee while transferring a relative out of a wheelchair. A large pulsatile mass in the posterior aspect of the left knee was palpated on physical examination, although he had warm distal extremities and 2+ distal pulses bilaterally. Magnetic resonance angiography revealed a 7.6 × 6.2 × 4.9 cm left popliteral artery pseudoaneurysm, which was subsequently treated with aneurysm exclusion with end to end reverse saphenous vein graft bypass. The development of a popliteal artery pseudoaneurysm after blunt knee injury without dislocation, fracture, or ligament injury is extremely unusual, but requires prompt treatment to avoid the potential complications of permanent functional impairment and limb loss.