MS-3390

MS-3390

A 68-year-old man presents to an orthopedic surgeon with a two-month history of dull pain in his left knee that is worse at night and unresponsive to over-the-counter pain relievers. Both knees appear normal with no swelling, tendon or ligament abnormalities, and no limited range of motion. The patient has a history of Paget disease of the bone and takes alendronic acid. The orthopedic surgeon notes a Codman triangle on knee X-ray due to periosteum elevation. What is the most likely condition affecting this patient?