The purpose of this study is to determine the predictive value of a composite of 3 simple clinically practical diagnostic tests (Mekhail's test, Patrick's and Thigh thrust) combined with a pain referral diagram in predicting response to a single diagnostic SIJ injection.

The purpose of this study is to determine the predictive value of a composite of 3 simple, clinically practical, diagnostic tests (Mekhail, Patrick's and Thigh thrust) combined with a pain referral diagram in predicting response to a single diagnostic SIJ injection. The goal is to test these 3 tests and compare their predictive value to the 6 tests commonly reported in the literature in order to provide a clinician with clinically practical special tests to aide in the diagnosis and treatment of SIJ mediated pain. . Specifically, we seek to evaluate the prognostic capacity for a series of three clinical tests (Mekhail's Test, thigh thrust and Patrick's Test) combined with a pain referral diagram to accurately predict the response (change in VAS) of a single diagnostic Sacroiliac joint and extra-capsular joint injection.

Inclusion Criteria:

• any patient presenting with low back pain with or without radicular symptoms, regardless of prior history of back surgery from 18-90 years old whom after being evaluated by an independent clinician in the Cleveland Clinic pain clinic has been scheduled for a diagnostic SIJ injection.

Exclusion Criteria:

• any patient less than 18 or greater than 90 years old, has any medical condition that would not allow them to complete the study, diagnosis of any recent fractures in the lumbar spine, recent infection, pregnancy, taking anticoagulants.