The Seated Flexion Test is a palpatory movement assessment used to observe relative movement of the posterior superior iliac spines during forward flexion in sitting. It is often used in sacroiliac-region assessment because sitting reduces the influence of the lower limbs compared with standing. A positive test is usually described as one PSIS moving earlier, higher or further than the other during seated flexion. However, current evidence suggests limited validity and variable reliability, so the test should not be used to diagnose SIJ dysfunction on its own.

Introduction

The Seated Flexion Test is commonly taught as a sacroiliac joint mobility or movement asymmetry test. The client sits while the professional palpates both posterior superior iliac spines. The client then bends forward, and the professional observes whether one PSIS appears to move differently from the other.

Although the test is simple to perform, interpretation is not simple. Palpatory tests of sacroiliac movement have important limitations because SIJ motion is small, difficult to feel accurately and influenced by examiner skill, client anatomy, soft tissue thickness, movement strategy and symptom behaviour.

For this reason, the Seated Flexion Test should be used as an educational movement observation tool rather than a stand-alone diagnostic test. A positive finding may support further assessment, but it does not confirm sacroiliac joint dysfunction, hypomobility or positional fault.

Quick Summary

Test name: Seated Flexion Test
Also known as: Sitting Flexion Test, SIFT
Body region: Sacroiliac joint region, pelvis and lumbar spine
Purpose: Observe relative PSIS movement during seated forward flexion
Commonly associated with: SIJ mobility assessment and pelvic movement asymmetry screening
Positive finding: One PSIS appears to move earlier, higher or further during forward flexion
Negative finding: No obvious asymmetrical PSIS movement or no meaningful side-to-side difference
Best used with: Standing Flexion Test, Stork Test, SIJ provocation tests, lumbar ROM, hip ROM and functional movement assessment
Key limitation: Reliability and validity are limited, especially between different examiners.

What Is the Seated Flexion Test?

The Seated Flexion Test is a manual palpation test performed with the client sitting. The professional places their thumbs over the left and right posterior superior iliac spines and asks the client to bend forward. The professional observes whether one PSIS moves more, earlier or higher than the other.

The seated position is intended to reduce lower-limb influence and focus observation more on pelvic and sacroiliac-region motion. However, because SIJ motion is very small and difficult to palpate reliably, the result should be interpreted cautiously.

Why It Is Used

The test is used to observe possible asymmetry in pelvic movement during forward flexion. It may help professionals decide whether to explore sacroiliac-region mobility, lumbar movement, hip range, hamstring flexibility, pelvic control or functional movement patterns in more detail.

The test may also be used as a teaching tool to help students learn anatomical landmark palpation, left-right comparison and the importance of recording movement findings carefully. It should not be used as a single test to label a client with SIJ dysfunction.

What It Assesses

The Seated Flexion Test assesses:

• Relative movement of the left and right PSIS during seated forward flexion
• Palpated pelvic movement asymmetry
• Ability to flex forward in sitting
• Possible differences in lumbopelvic movement strategy
• Symptom response during seated flexion
• Examiner ability to locate and track PSIS movement

It does not reliably confirm sacroiliac joint hypomobility, sacroiliac positional fault, SIJ dysfunction or the source of pain.

Who It Is Useful For

This test may be useful for adults with low back, posterior pelvic or hip-region symptoms when the professional wants to observe seated lumbopelvic movement and palpated pelvic asymmetry.

It may also be useful for students and professionals learning pelvic landmarking and movement observation. However, the test should be interpreted with care because palpatory mobility tests have variable reliability and limited validity.

When to Use This Test

Use the Seated Flexion Test when:

• The client can sit safely and flex forward
• You want to observe seated lumbopelvic movement
• You want to compare PSIS movement from left to right
• You are using the test as part of a broader assessment
• You can record symptoms, movement quality and uncertainty
• The result will guide further assessment rather than a stand-alone conclusion

When Not to Use or When to Be Cautious

Use caution or avoid the test when the client cannot sit safely, has severe pain with flexion, has worsening neurological symptoms, has acute trauma, reports dizziness or instability in sitting, or cannot tolerate forward bending.

The test should also be interpreted cautiously in clients with high symptom irritability, significant anatomical landmarking difficulty, marked soft tissue sensitivity, or strong fear of forward flexion.

Equipment Required

The Seated Flexion Test requires minimal equipment:

• Chair, plinth or treatment table allowing stable sitting
• Pain rating scale
• Symptom-location recording method
• Measurz app for structured documentation
• Optional video for movement review
• Optional MAT movement assessment notes for related tests

Within Measurz, the Seated Flexion Test can be recorded alongside Standing Flexion, Stork Test, lumbar ROM, hip ROM, SIJ provocation tests and functional movement assessments. Measurz can also be used to document pain score, symptom location, movement quality, side-to-side difference and confidence in the finding.

Step-by-Step Protocol / Practice

Setup

Explain that the test involves bending forward while seated and that you will be observing pelvic movement. Gain consent before palpating the posterior pelvis.

Ask the client to report any pain, pulling, stiffness, symptom spread or familiar symptoms during the movement.

Client position

The client sits upright on a firm chair, plinth or treatment table. Feet may rest flat on the floor if seated on a chair, or hang comfortably if seated on a plinth. The pelvis should start as level as possible.

Examiner/professional position

Stand or sit behind the client. Position yourself so both posterior superior iliac spines can be palpated evenly without leaning or twisting.

Hand placement

Place one thumb or finger pad on each PSIS. Confirm landmark position carefully before movement begins. Avoid pressing excessively into sensitive tissue.

Stabilisation

No external stabilisation is usually required. The client should remain balanced and move slowly enough for the professional to observe relative PSIS movement.

Movement or force direction

Ask the client to bend forward from sitting as far as comfortably possible. The movement should be slow, controlled and repeated only if tolerated.

Instructions

Ask:

“Slowly bend forward as far as comfortable.”
“Tell me if you feel pain, pulling or familiar symptoms.”
“Return to upright when ready.”
“Let me know if symptoms change or spread.”

Positive finding

A positive finding is commonly described as one PSIS appearing to move earlier, higher or further than the other during seated forward flexion. The side with greater or earlier superior movement is often considered the side of altered movement, but this interpretation should be made cautiously.

Negative finding

A negative finding is no clear side-to-side difference in PSIS movement and no meaningful symptom reproduction during the movement.

Stopping criteria

Stop if pain increases sharply, symptoms spread, neurological symptoms worsen, dizziness occurs, the client cannot return from flexion safely, or the client asks to stop.

Safety notes

Avoid overinterpreting small palpatory differences. Record uncertainty when the finding is unclear. Do not describe the test as diagnosing SIJ dysfunction.

Positive and Negative Test Interpretation

A positive Seated Flexion Test may suggest observable or palpated asymmetry during seated forward flexion. It may indicate that further assessment of lumbopelvic movement, hip mobility, lumbar flexion, SIJ provocation response or functional movement is appropriate.

A positive result does not confirm sacroiliac joint dysfunction, hypomobility, joint restriction, positional fault or pain source. Palpated PSIS movement is difficult to assess reliably, and the test can be influenced by lumbar movement strategy, hamstring tension, pelvic control, body shape, examiner landmarking and client guarding.

A negative test means no clear PSIS movement asymmetry was observed under the conditions tested. This does not exclude sacroiliac-region involvement, lumbar involvement or movement-related symptoms. It simply means this specific palpatory movement test did not show a clear asymmetry.

Sensitivity, Specificity and Diagnostic Accuracy

At the time of writing, high-quality diagnostic accuracy evidence reporting sensitivity, specificity, likelihood ratios or diagnostic odds ratios for the Seated Flexion Test as a stand-alone test for painful SIJ involvement appears limited.

This is important because the Seated Flexion Test is a mobility palpation test rather than a pain provocation test. It attempts to assess movement asymmetry, not whether a specific load reproduces familiar pain. Current evidence for SIJ mobility tests suggests that diagnostic certainty is limited and that these tests should not be used as stand-alone tools for identifying SIJ pain or dysfunction.

A 2021 construct validity and reliability study of the Standing Flexion Test and Sitting Flexion Test reported limited findings for the Sitting Flexion Test. In that study, the Sitting Flexion Test had 56.7% agreement and kappa 0.29 for construct validity, 56.7% agreement and kappa 0.38 for intra-rater reliability, and 13.3% agreement with kappa 0.01 for inter-rater reliability. The authors concluded that the Sitting Flexion Test did not reach minimum scores for construct validity or reliability in their healthy sample.

Because of these limitations, the Seated Flexion Test should be interpreted as a movement observation and palpation finding rather than a diagnostic test with strong accuracy values.

Reliability and Validity

Reliability and validity are key limitations of the Seated Flexion Test. The test relies on palpating small pelvic landmark movements, which can be difficult even for experienced professionals.

A 2021 systematic review and meta-analysis of palpatory SIJ mobility tests found that the sitting flexion test showed good and statistically significant intra-examiner agreement in the pooled analysis. However, the same body of evidence also highlighted the need for further research into validity, and intra-examiner reliability does not mean the test is accurate or reliable between different examiners.

Another 2021 study found poor inter-rater reliability and limited construct validity for the Sitting Flexion Test. This means different professionals may not agree on the result, and the test may not measure what it is intended to measure with enough certainty.

To improve consistency, professionals should use careful landmarking, slow movement instructions, repeated observation when appropriate, clear documentation and cautious language.

Common Errors and Limitations

Common errors include:

• Pressing too hard on the PSIS
• Misidentifying pelvic landmarks
• Moving the thumbs during the test
• Asking the client to move too quickly
• Interpreting a very small difference as clinically meaningful
• Assuming asymmetry confirms SIJ dysfunction
• Ignoring lumbar or hip contributions
• Failing to record symptom response
• Not documenting uncertainty
• Comparing results between professionals without considering reliability limitations

Limitations include small SIJ motion, palpation difficulty, poor inter-rater reliability in some studies, limited validity evidence and the influence of client movement strategy.

Practical Applications

The Seated Flexion Test can be useful as part of a broader movement assessment. It may help professionals observe how the client flexes in sitting, whether symptoms are reproduced, and whether there appears to be a left-right pelvic movement difference worth exploring further.

It may also be useful for teaching landmark palpation and assessment reasoning. The most useful outcome is often not the label “positive” or “negative”, but the detail recorded: movement quality, symptom response, side-to-side difference, confidence and whether other tests support the finding.

How to Record This in Measurz

In Measurz, record:

• Test name: Seated Flexion Test
• Starting position
• Seat type or table height
• Foot position
• Side of observed PSIS movement difference
• Result: positive, negative, unclear or unable to test
• Pain score before, during and after
• Symptom location
• Symptom quality
• Whether symptoms were familiar
• Range of seated flexion
• Movement quality
• Speed of movement
• Guarding or compensations
• Landmarking confidence
• Examiner confidence in result
• Comparison with Standing Flexion or Stork Test
• Related lumbar, hip and SIJ provocation findings
• Reason for stopping if applicable
• Retest date if relevant

Recording these details improves repeatability, communication, professional education, reassessment quality and team consistency.

Related Tests / Internal Links

• Standing Flexion Test
• Stork Test
• Sacroiliac Distraction Test
• Sacroiliac Compression Test
• Sacral Thrust Test
• Thigh Thrust Test
• Gaenslen Test
• Lumbar Flexion Test
• Hip ROM Assessment
• Functional Movement Assessment

FAQs

What is the Seated Flexion Test used for?

It is used to observe relative PSIS movement during seated forward flexion and to support broader lumbopelvic assessment reasoning.

Does the Seated Flexion Test diagnose SIJ dysfunction?

No. It does not diagnose or confirm SIJ dysfunction. Reliability and validity limitations mean it should not be used as a stand-alone diagnostic test.

What is a positive Seated Flexion Test?

A positive finding is usually described as one PSIS moving earlier, higher or further than the other during seated forward flexion.

What is a negative Seated Flexion Test?

A negative result means no clear side-to-side PSIS movement difference was observed during the test.

Why is the test performed in sitting?

Sitting reduces some lower-limb influence compared with standing, which may make pelvic movement observation easier. However, this does not remove the test’s reliability and validity limitations.

Is the Seated Flexion Test reliable?

Evidence is mixed. Some pooled intra-examiner findings are more favourable, but inter-rater reliability and construct validity remain concerns.

What should be recorded in Measurz?

Record side, movement quality, pain score, symptom location, PSIS movement difference, confidence, uncertainty and related findings.

Key Takeaways

The Seated Flexion Test is a palpatory lumbopelvic movement assessment.
A positive result suggests observed PSIS movement asymmetry, not a confirmed diagnosis.
Reliability and validity are limited, particularly between different examiners.
The test is best used as part of a broader assessment, not in isolation.
Measurz should capture movement quality, symptom response, side-to-side findings, confidence and related tests.

References

Klerx, S. P., Pool, J. J. M., Coppieters, M. W., Mollema, E. J., & Pool-Goudzwaard, A. L. (2020). Clinimetric properties of sacroiliac joint mobility tests: A systematic review. Musculoskeletal Science and Practice, 48, 102090. https://doi.org/10.1016/j.msksp.2019.102090

Ribeiro, R. P., Guerrero, F. G., Camargo, E. N., Pivotto, L. R., Aimi, M. A., Loss, J. F., & Candotti, C. T. (2021). Construct validity and reliability of tests for sacroiliac dysfunction: Standing flexion test (STFT) and sitting flexion test (SIFT). Journal of Osteopathic Medicine, 121(11), 849–856. https://doi.org/10.1515/jom-2021-0025

Ribeiro, R. P., Guerrero, F. G., Camargo, E. N., Beraldo, L. M., Pivotto, L. R., Candotti, C. T., & Loss, J. F. (2021). Validity and reliability of palpatory clinical tests of sacroiliac joint mobility: A systematic review and meta-analysis. Journal of Manipulative and Physiological Therapeutics, 44(4), 307–318. https://doi.org/10.1016/j.jmpt.2021.01.001

Saueressig, T., Owen, P. J., Diemer, F., Zebisch, J., & Belavy, D. L. (2021). Diagnostic accuracy of clusters of pain provocation tests for detecting sacroiliac joint pain: Systematic review with meta-analysis. Journal of Orthopaedic & Sports Physical Therapy, 51(9), 422–431. https://doi.org/10.2519/jospt.2021.10469