Review Question - QID 213367

A 57-year-old man with a history of chronic lower back pain and right hip arthritis is postoperative day 2 from an uncomplicated right total hip arthroplasty with a spinal block. Since the procedure, he has reported persistent pain in his right leg with a focal point in the proximal lateral leg. He has had difficulty getting out of bed for physical therapy due to pain reproduced in his leg. He is voiding but has not yet had a bowel movement. Physical exam is only significant for decreased ankle dorsiflexion strength on the right. Plantarflexion strength remains 5/5 bilaterally. No point tenderness was elicited and Homan's sign is negative. His wound is unremarkable with typical post-operative swelling of the leg and no significant drainage. He has been receiving ASA 81mg PO daily since surgery and has been wearing compression stockings full-time. Postoperative repeat radiographs of the hip are unremarkable and his hemoglobin is stable. Which of the following etiologies is most likely responsible for this patient's symptoms?