During an osteopathic exam, if the patient's right Posterior Superior Iliac Spine (PSIS) raises as they bend forward, on which side is the somatic dysfunction located?

Osteopathic Standing Flexion Test: Somatic Dysfunction Localization

When the right PSIS rises during forward bending in the standing flexion test, the somatic dysfunction is located on the right side. This indicates restricted motion of the right sacroiliac joint, where the right ilium is "locked" and moves as a unit with the sacrum rather than moving independently.

Understanding the Standing Flexion Test Mechanism

The standing flexion test evaluates sacroiliac joint motion by monitoring PSIS movement during forward flexion:

• Normal motion: As a patient bends forward, both PSISs should move superiorly and equally, with the ilia rotating anteriorly on the sacrum 1
• Abnormal motion: When one PSIS rises more than the other (or rises first), it indicates restricted motion on that side 1
• Interpretation principle: The side that moves MORE (rises higher) is the dysfunctional side, as the ilium and sacrum are moving together as a fixed unit rather than the ilium gliding normally on the sacrum 1

Clinical Reasoning

The dysfunctional side paradoxically shows MORE motion, not less:

• In your case, the right PSIS rising indicates the right sacroiliac joint has restricted mobility 1
• The right ilium cannot glide properly on the sacrum, so it "carries" the sacrum with it during flexion 1
• This creates the appearance of increased PSIS movement on the restricted side 1
• The left side (normal) shows less PSIS rise because the left ilium is gliding normally on the sacrum 1

Correlation with Somatic Dysfunction Patterns

Regional assessment context:

• Somatic dysfunction in the sacrum/pelvis region is highly prevalent, occurring in approximately 28% of patients with chronic low back pain 1
• Sacrum/pelvis somatic dysfunction strongly correlates with pelvis/innominate dysfunction (correlation coefficient ρ=0.71) 1
• The presence of severe somatic dysfunction in the sacrum/pelvis region is associated with greater back-specific disability and poorer general health outcomes 1

Clinical Application

Assessment approach:

• The standing flexion test should be performed bilaterally, monitoring both PSISs simultaneously during forward bending 1
• Tissue texture abnormality, asymmetry, restriction of motion, and tenderness (TART criteria) should be assessed to confirm somatic dysfunction 1, 2
• The finding should be correlated with other osteopathic examination findings in the lumbar and pelvic regions 1

Common pitfall to avoid:

• Do not confuse this with the seated flexion test, which evaluates different biomechanical relationships and may yield different lateralization 1
• The standing flexion test specifically assesses iliosacral motion, while seated testing evaluates sacroiliac motion 1