Spondylosis is a general finding of Xray Spine and is many times not related to your pain at all. Although, Listhesis of Grade1-2 can cause pain depending upon the compression of neural canal structures of your back. It happens when your spine undergoes some trauma and causes one bone to slip over another, causing pain. If you are suffering from brittle bones (osteoporosis), then it may occur in absence of any trauma. You need some antiinflammatory medications, along with strengthening of abdominal muscles (remember, extension exercises of spine are contraindicated in listhesis, and should be avoided to prevent further worsening). If conservative method fails, a surgery to fix the affected segments might be needed.