Review Question - QID 7473

A 59-year-old woman seen in the emergency department reports the rapid onset of pain in the left lower quadrant of her abdomen radiating to the anterior thigh that began about 4 to 5 hours ago. She also notes that now her left knee is buckling, causing her to fall to the ground. History reveals that the woman is an alcoholic and takes warfarin for atrial fibrillation. Examination reveals 1/5 quadriceps strength and pain on hip flexion against resistance. What is a likely pathoanatomic cause for her problem that should be rapidly evaluated to prevent permanent damage?