Validity and Reliability of Diagnostic Findings of SI Joint Blocking

Subjects with suspected SI joint pain will undergo 3 SI joint blocks, 2 with local anesthetic and 1 sham block. The sequence of blocks is randomly assigned. This study examines both the test-retest reliability of response to diagnostic sacroiliac (SI) joint injection and the specificity of response to local anesthetic or sham block. The goal of the study is to validate the use of diagnostic SI joint block. Subjects with pain suspected to be generated by one SI joint will undergo three diagnostic SI joint blocks each separated by one week. Two blocks will be with local anesthetic (LA) and one will be a sham block (SB). Both the Coordinator (collecting pain assessments) and subject will be blinded to the sequence of blocks (LA or SB each time). The sequence of blocks will be randomly assigned for each subject on study. The subject's participation in the study is complete after 6-month post-procedure assessment.