spine MRI

just got my MRI images of L5/S1-- i had a discectomy 15 years ago--the MRI shows a white haze on the lower one third of L5 vertebrae and the same on the upper one quarter of the S1 vertebrae---it also shows a horn on the posterior of the body about 2x larger then the other vertebrae---I know its almost time to go back in for surgery can anyone give me a quick run down on the fog?  

[EdwardPB]

I'm not sure what you mean by "fog/haze."
White equals bone, or solid material. Darker equals air or fluid.
You want your disk spaces to look dark, and the bones to look white.
The "horn," I'm guessing is what's called an osteophyte.
They are not significant in themselves. However, they can be significant if protruding into nerve space. Plus, they are an indication of bone wear due to arthritis. (whether disk degeneration, herniation, trauma, etc)

What it boils down to, is:
Why did you get the MRI? The your questions are potentially the least relevant to your symptoms, and most likely a factor of the underlying cause.