Cluster of Laslett | Sacroiliac Joint Pain Provocation | SIJ Assessment

The Cluster of Laslett is a tool used in low back pain assessment. One of your hypotheses might be that your patient’s pain is originating in the SI joint. The Cluster of Laslett originally describes 6 provocative tests. Eventually, Laslett proposes an algorithm comprising 4 provocative tests to identify the SI joint as the source of pain as the other two tests didn’t have additional diagnostic value. It has a reported sensitivity of 88% and specificity of 78% for 2 or more positive tests.

You can increase the specificity when the patient’s symptoms don’t centralize as described by McKenzie.

• Distraction test: The patient lies supine with the legs extended. You are going to stand on the symptomatic side and place your hands on the patient’s anterior superior iliac spines. Then apply 3-6 moderate velocity thrusts and gradually increase pressure in a dorsolateral direction.
• Thigh Thrust test: Your patient lies supine and you are going to stand on the asymptomatic side. Flex the leg on the symptomatic side to 90° of hip flexion.  Place one hand over the sacrum and then apply longitudinal pressure through the patient’s femur creating a shear force in the SI joint. Apply 3-6 higher velocity thrusts with gradually increasing pressure
• Compression test: Ask your patient to lie on the asymptomatic side with the hips flexed to 45° and knees bent to 90°. You are going to position yourself behind the patient and place your hands on the anterior rim of the ilium. They apply 3-6 vertical thrusts with moderate velocity and gradually increasing pressure.
• Sacral thrust test: For the sacral thrust test, your patient is going to lie in prone position. You are going to stand next to the bench and place the palm of your hand over spinal level S2. The direction of pressure is going to be vertically downwards. Apply 3-6 higher velocity thrusts and gradually increase pressure.

The 5th test mentioned in the literature is the Gaenslen Test. As this test does hardly contributes to the accuracy of Laslett’s test battery, it was included in the recommended algorithm by the author.

For all tests, you are looking for the reproduction of your patient’s familiar pain. Be aware that the thrusts are not manual therapy thrusts. As these techniques are pain provocation techniques, be careful and start gently first. Sometimes just a single pressure is enough.

Mark Laslett, the author of the cluster proposes a diagnostic algorithm to evaluate the outcomes of each individual test. Overall, the rule of thumb is 2/4 positive tests are needed to diagnose a symptomatic SI joint. If the first two tests are positive, the SI joint is likely the source of pain, and no further testing is needed.

If you fail to provoke pain during the first two tests, continue with the third test. If this test is positive and you now have 2 positive tests, the SI joint is likely the source of pain.

In case that the third test is negative as well, continue with the sacral thrust test. If two tests are positive now, the diagnosis is likely a symptomatic SI joint. Are less than 2 or even all tests negative? Then SIJ pain can be ruled out or is at least unlikely.

Another common test battery to diagnose a symptomatic sacroiliac joint is the Cluster of van der Wurff.

21 OF THE MOST USEFUL ORTHOPAEDIC TESTS IN CLINICAL PRACTICE

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Laslett M, Aprill CN, McDonald B, Young SB. Diagnosis of sacroiliac joint pain: validity of individual provocation tests and composites of tests. Manual therapy. 2005 Aug 1;10(3):207-18.