Past documentation is good, but your best bet is to get a current DBQ - Disability Benefit Questionnaire completed by an outside Orthopedic Surgeon of your choice. It asks roughly the same questions as should have been answered in the C&P, but from a source other than the VA.
I suggest you download the spinal DBQ from the VA website and hand a hard copy to the civilian physician to fill out. Tell them you want to hold on to it for an upcoming appeal. That way you have a chance to look it over and see if you agree with it and it helps you BEFORE the VA has their hands on it. Call it Quality Assurance. If you let the physician download and immediately upload it back to the VA, that's out the window.
At the PEB stage, once your VA ratings come back you can submit a VARR VA Ratings Reconsideration, with the DBQ as strong evidence. You can do it earlier, but run the risk of the VA ignoring it or filing it in the trash, and then it's not new evidence and "might" be disallowed at the PEB stage for a VARR.
The good news is, if the VA and the DBQ exams and opinions disagree on the same ratable issue, the VA is REQUIRED to use the higher rating.
Remember your BIG fight at the MEB stage is not about ROM, but getting ANY and ALL conditions that should NOT meet Retention Standards to be listed accordingly by the MEB, even if that means doing an appeal at the MEB stage.
It's those conditions that do NOT meet Retention Standards, that the PEB keys on to decide what conditions are Unfitting, and it's the Unfitting conditions that count for the DOD combined rating, which is what decides if you are Medically Separated (without benefits) or Medically Retired (with benefits, including Tricare Medical Insurance for life).
For spinal injuries, if you have pain and numbness in your legs, that's called "Radiculopathy" and it is a Rated condition that does NOT meet Retention Standards, depending on severity. It's rated for EACH leg separately. It falls under AR 40-501 Army Retention Standards, paragraph 3-30j. (if you're in another service you'll have to look up for your branch).
In my case, on appeal to the MEB they added Radiculopathy for EACH leg as NOT meeting Retention Standards. That was KEY at the PEB stage, as the radiculopathy was rating 10% right leg, 10% left leg. That combined with even 10% for my back (initially) was enough to meet the 30% combined DOD rating threshold for Medical Retirement.
My best advice, get the DBQ done for a later battle, and be prepared to fight for the best outcome at the MEB to set you up for success at the PEB stage. Chess not Checkers.
Good Luck
Hope this Helps...