Hi, Thanks for writing in. There is posterior compression on covering of spinal cord at level of vertebra S 1. This is due to minimal malalignment of the bones after fusion of L 4 - L 5 - S1. Dessication of disc implies loss of water content. The nerve roots pass through neural foramina on the sides between vertebrae at all levels from cervical through lumbar spine and you might have severe nerve root compression at the affected levels. The nerve pain may be controlled with restricted physical activity and pain relief medication. Please do not do heavy physical activity till you are comfortable. Surgery is indicated due to severe nerve root compression and pain which is not responsive to medications taken for few months.