A 64-year-old woman with no known medical history presented to clinic with a 4-year history of worsening low back pain and difficulty walking. Exam was notable for a finding in the eyes, kyphosis, and a Trendelenburg gait. Radiographs of the lumbosacral spine and pelvis are shown. A urine sample turned black after being left at room temperature overnight. What is the most likely diagnosis? Submit your answer and see how others responded: https://nej.md/IC10082026