I am guessing you have not been rated since 2003. In 2003 they changed the criteria for rating disease and injury to the spine.
This link goes to the VASRD. It will show you the current criteria.
http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=d741c52f7d5b47cff93ecd0ec686fc0a&rgn=div5&view=text&node=38:1.0.1.1.5&idno=38
You should search for code 5237 or 5243.
Mike
