Question about Vertebro/Kyphoplasy on old fractures?

Hi Dr.'s and members: I've been doing research on Vertebro/Kyphoplasty for years, and can't find the answer to my question. Can either procedure be done on an old fracture? What I mean by old is at least one year post fracture? Does anyone know if this can be done. Also, is one procedure over the other used specifically for older fractures, or does the fracture have to be fresh for either procedure to work? What is your experience with these procedures and their outcomes, compared to non surgical intervention. I read that conservative tx, no surgery or rehab with bracing, can be just as successful as the two fracture procedures using cement, is this true? A couple other things, can you have either vertebro/kypho done on an area that has pedical screws and rods in place, and severe spinal stenosis, with a frax? If it can be done would the hardware have to be removed? I'm asking this question for myself and a friend that has 4 old lumbar (1 1/2 years old) frax's. Sorry that this is a multiple question, but I have one last concern and that is, are most grade 2 spondy's caused by a frax, or something else?

I can't find anymore research that would answer these questions. Do we have a Ortho Surgeon, Neuro Surgeon or Radiologist on this site, or someone well versed in the ver/kyphoplasty procedures.

Thanks for any help you can provide.