Gillet's Test: How to Assess Sacroiliac Joint Mobility

The sacroiliac joint is one of the usual "suspects" when someone has pain in the lower back or glute area, especially if it's one-sided. Gillet's test (also known as the stork test) is one of the classic tests for assessing the relative movement between the sacrum and ilium during hip flexion.

What does this test measure?

Gillet's test assesses sacroiliac joint mobility, by comparing the movement of the posterior superior iliac spine (PSIS) relative to the sacrum when the client flexes the hip on that side while standing on one leg.

Under normal conditions, the PSIS on the side flexing the hip should move downward and medially relative to the sacrum. If this doesn't happen (or it moves the opposite way), it's interpreted as a possible sacroiliac mobility restriction on that side.

Equipment needed

• Nothing essential
• A stable surface so the client can maintain single-leg standing without losing balance

Test protocol

1. The client stands with their back to you
2. Place one thumb on the posterior superior iliac spine (PSIS) of the side being assessed and the other thumb on the sacrum, at the same level (for example, over S2)
3. Ask the client to flex the hip and knee on the side being assessed, bringing the knee toward the chest (like a stork posture, hence the name stork test)
4. Observe the relative movement of your thumb on the PSIS compared to the one on the sacrum
5. Repeat on the other side to compare

Common mistakes

• Palpating bony landmarks incorrectly, especially in people with a lot of soft tissue in the area
• Asking the client to lean or compensate with the trunk during hip flexion, which alters the actual pelvic movement
• Drawing conclusions from only one side without comparing with the contralateral side

How to interpret the result

Result	Interpretation
Normal: the PSIS on the flexing side moves downward relative to the sacrum	Sacroiliac mobility preserved on that side
Positive (restricted): the PSIS doesn't move, or moves upward/the same as the sacrum	Suggests a sacroiliac joint mobility restriction on that side

The inter-rater reliability of Gillet's test is limited in the literature, so it's recommended not to base clinical decisions solely on this test, but to combine it with sacroiliac pain provocation tests and the clinical history.

Relationship with other tests

Gillet's test is usually combined with:

• Gaenslen's test — a sacroiliac pain provocation test, complements the mobility assessment
• Sacroiliac traction/compression test — to confirm whether the sacroiliac joint is a real source of pain

Tracking with Movalytics

Sacroiliac mobility can change with hip mobility and lumbopelvic control work. In Movalytics you can log the result of Gillet's test for each side across successive assessments, and relate it to the evolution of the client's reported lumbopelvic pain.

Frequently asked questions

Does Gillet's test hurt? It shouldn't — it's a mobility test, not a pain provocation test. Is this test reliable? Its inter-rater reliability is debated in the literature, so it's recommended to use it as part of a broader battery, not in isolation. Can a "locked" sacroiliac joint be noticed just by looking? Not always. That's why manual tests like Gillet's are used, although always with their accuracy limitations.