Sacroiliac (SI) joint problems require appropriate interpretation of a patient’s history, clinical exam results, and imaging studies. Differential diagnostic approach, including the SI joint, the spine, and the hip, must be used to accurately assess and identify the actual pain generator(s).
During physical exam, patients with sacroiliac (SI) joint pain may exhibit any/all of the following symptoms:
- Low back pain
- Palpable tenderness of the posterior pelvic sacroiliac (SI) region
- Pain from provocative maneuvers to the hip (i.e. Faber test) and the absence of neurologic deficit
- Joint asymmetry may be seen on CT and MRI.
When the SI joint is suspected as the source of the patient’s low back pain, confirmation is provided by CT or fluoroscopic guided injection. This injection is the diagnostic "Litmus test." If Lidocaine is injected into the joint and symptoms temporarily resolve, this is confirmation of the SI joint as the source, or a source, of the patient’s low back pain (as multiple pain generators may co-exist).
Evaluating the SI Joint
A comprehensive approach to SI joint evaluation might look like this:
- Recognize patient history of SI joint problems
- Perform physical examination:
- Provocative tests (minimum 3 out of 5 tests should be positive)
- Review or order imaging studies – for abnormalities / asymmetry
- Administer diagnostic injections (75% pain relief from one injection, or 50% pain relief from two injections to confirm SI joint diagnosis)
Basics of the SI Joint Exam
Provocative Tests for Sacroiliac (SI) Joint Disorders
After assessing the patient for existence of tenderness upon palpation, there are a series of provocation tests that will generate pain in patients with SI joint problems and should be included in the examination. The rule of thumb for a positive diagnosis of the SI joint as a pain generator is pain provoked in at least 3 out of 5 of the following tests:
Diagnosing SI Joint Disorders: Provocative Testing
FABER - (Flexion, ABduction, External Rotation)
This test applies tensile force on the anterior aspect of the SI joint.
The patient lies supine as the examiner crosses the same side foot over the opposite side thigh. A force is steadily increased through the knee of the patient, exaggerating the motion of hip flexion, abduction, and external rotation.
The pelvis is stabilized at the opposite ASIS with the hand of the examiner.
This applies lateral compression force across the SI joint.
The patient is placed in a side-lying position, facing away from the examiner, with a pillow between the knees.
The examiner places a downward pressure through the lateral aspect of the patient’s top side ASIS and pelvis, anterior to the greater trochanter.
This test applies anteroposterior shear stress on the SI joint.
The patient lies supine with one hip flexed to 90 degrees. The examiner stands on the same side as the flexed leg. The examiner provides either a quick thrust or steadily increasing pressure through the line of the femur.
The pelvis is stabilized at the sacrum or at the opposite ASIS with the hand of the examiner (not pictured).
This applies tensile forces on the anterior aspect of the joint.
The patient lies supine and is asked to place their forearm behind their lumbar spine to support the natural lordosis (not pictured). A pillow is placed under the patients knees (not pictured). The examiner places their hands on the anterior and medial aspects of the patient’s ASIS’s with arms crossed.
A slow and steadily increasing pressure is placed through the arms and held.
This test applies torsional stress on the SI joints.
The patient lies supine with the near side leg hanging off the table. The patient is asked to hold the opposite side knee in flexion. The examiner applies an extension force to the near side thigh and a flexion force to the opposite knee. The patient assists with opposite side hip flexion. This is performed bilaterally.
Diagnostic SIJ injection
- Posterior & inferior approach
- 22 gauge 5" styletted needle
- 0.25ml contrast medium
- 1.25ml Lidocaine
Recommended Sacroiliac (SI) Joint Injection Technique
The most common means for confirming sacroiliac joint disorders is an injection with CT or fluoroscopic guidance accurately placed in the SI joint. The pain response indicates the role of the SI joint in each case:
- If no pain improvement, then test was negative. SI joint is not a pain generator.
- If > 75% pain improvement, then test was positive. SI joint is considered a pain generator.
- If 50-75% pain improvement, then test was equivocal. Repeat to confirm SI joint as a pain generator, and consider the existence of multiple pain generators.
If symptoms are decreased by a minimum of 75% with one injection or by 50% each time with two injections, it can be concluded that the SI joint is either the source, or a major contributor, to the particular patient's low back pain.
Diagnosing SI Joint Disorders: Diagnostic Injection Demonstration
Reference Tools--Print out the following resources to aid in your diagnosis of Sacroiliac (SI) Joint Disorders:
- Management Algorithm For SI Joint Complaints
- Recommended Sacroiliac Joint Injection Technique (two-page article)
If your patients have low back symptoms that are SI joint in origin, learn more about treating SI joint disorders and using a minimally invasive surgical (MIS) approach called the iFuse Implant System®.
The iFuse System is intended for sacroiliac joint fusion for conditions including sacroiliac joint disruptions and degenerative sacroiliitis. As with all surgical procedures and permanent implants, there are risks and considerations associated with surgery and use of the iFuse Implant. Please review the iFuse Instructions For Use for a complete discussion of contraindications, warnings, precautions, and risks.