Diagnosing Sacroiliac (SI) Joint Disorders | SI Joint Exam

Diagnosis

Diagnosis of the SI Joint as a Source of Symptoms

Sacroiliac (SI) joint disorders require appropriate interpretation of a patient’s history, clinical exam results, and imaging studies. Imaging alone is often not helpful in diagnosis. Often hip pathology and lumbar pathology coexist with SI joint pathology. During physical examination, patients with SI joint disorders exhibit any/all of the following symptoms:

Low back pain
Palpable tenderness of the posterior pelvic sacroiliac (SI) region
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 image-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 of the patient’s low back pain.

SI Joint Exam

Differential diagnosis to rule out other sources of pain.
Point to pain while standing (Fortin Test)
Tenderness over SIJ sulcus
Posterior SIJ tender to palpation
Position test(s) to check for pelvic symmetry

Single leg stance test may induce pain on supporting side
Provocative Tests (see below)
- 3 of 5 must be positive (Thigh Thrust, Compression, Gaenslen, FABER, Distraction)
- 1 of 3 positive results must be Thigh Thrust or Compression
Diagnostic injections of the SI joint

Provocative tests:

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.

Compression

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.

Thigh Thrust

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).

Distraction

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 maintained.

Gaenslen

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.