Review Question - QID 4642

A 70-year-old woman is seen back in follow-up in your clinic with persistent shooting pains down the back of her legs, which have been increasing over the last nine months. She can walk for about 3 minutes before the pain becomes unbearable. It is relieved only when she sits down or bends forward. Her neurological exam demonstrates difficulty with heel-walking and normal patellar tendon reflexes bilaterally. Pedal pulses are present. Figures A and B show a lateral x-ray and a sagittal MRI of her lumbar spine. She has failed all previous conservative management and would like to proceed with surgery. What is the most appropriate treatment?