In some people the lumbar sacral joint is particularly stable. If this occurs what we’ve got is the kind of anchoring at one level and then the forces that it enacts on the spine are more likely to cause slippage. This actually occurs frequently in African-Americans. And one of the theories tells when this anchoring occurs you are more likely to get anterolisthesis and therefore it’s been said that African-Americans are treated 2-4 times the prevalence of anterolisthesis as in white people. As you can see here at L4-L5 80% of it occurs there.