The investigators propose to investigate a cluster of tests proposed by Laslett as well as compare the results of the ASLR and the Gillet Test both before and after SIJ injection to determine the validity of these tests in a low back patients presenting for injections thought to be from the sacroiliac joint. The secondary purpose would be the development of a clinical predictor rule to determine examination characteristics of patients who may benefit from intraarticular injections of the SIJ.