Review Question - QID 212516

A 65-year-old man presents to the emergency department with back pain. The patient states that he has gradually worsening back pain that seems to have worsened after moving furniture the other day. He also states that while he walks, he feels numbness and weakness in his legs. The only time the patient states his back pain is improved is when he is riding his bike or pushing a cart at the grocery store. The patient has a past medical history of osteoporosis, dyslipidemia, and diabetes. He drinks 3 alcoholic drinks every day and has a 44 pack-year smoking history. His temperature is 99.5°F (37.5°C), blood pressure is 157/108 mmHg, pulse is 90/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for a non-tender spine with normal mobility in all 4 directions. Radiography of the spine and basic labs are ordered. Which of the following is the most likely diagnosis?