What Does Grade 1 Anterior Subluxation Of L4 On L5 And Severe Disc Space Narrowing At L5-S1 Indicate?

Hi Dr., I had back surgery 12-31-2013. Since my surgery I have had no pain at all in my back. However before the surgery, my right leg has drop foot (this is why I had emergency back surgery), It has not recovered . Last week I slipped on the ice and yesterday I had x-rays done yesterday. I just picked up my report and The findings were There is posterior fusion of L3-L5 with disc innerspace devices. Vertebral body heights are within normal limits. There is grade 1 anterior subluxation of L4 on L5. L5-S1 has sever disc space narrowing. Impression: 1. Lower lumbar fusion as described above. Hardware appears intact. 2. Grade 1 anterior subluxation of L4 on L5. 3. Severe disc space narrowing of L5-S1. I have not been able to get ahold of my back surgeon and am very scared. I am in a lot of pain now. I have not had any pain since my back surgery. My drop foot is making it easy for me to fall. I wear an AFO on my right leg. Can you explain to me if this situation is severe and if I messed up perfect back surgery by my fall. What is Grade 1 anterior subluxation of L4 on L5. Will this require another surgery. I am scared to death. The L5-S1 severe disc space narrowing, I don t believe would be caused by falling. If it is can you let me know. I just turned 55 and currently have no one to get answers from. I lost my husband in 2011 at the age of 53, so I am very scared and depressed that I may have real hurt myself and require another surgery. Can you help explain what this report means. Thank you, Kim