Q. A 65 year-old woman presents with low back pain and trouble with walking over the past few years. She has difficulty with prolonged standing but she walk uphill without pain (although it is painful going downhill), and she can push a grocery store cart for a long time without issue. She has a known history of coronary artery disease. No tobacco alcohol or drug use. Temperature is 36.7 (98.7 F), Blood Pressure is 130/80, Heart Rate is 72 beats/minute. Neurological examination is normal. Dorsalis pedis pulses and full and equal bilaterally in the feet. There is no tenderness to palpation across the spine and the straight leg raise test is negative. Cardiopulmonary auscultation is normal. Which is the most appropriate test to order?