What is the Standing Flexion test?

Standing flexion test or standing forward flexion test is used to assess the sacroiliac joint dysfunction, i.e., hypomobility of the sacroiliac joint. This test mainly involves the sacroiliac joint, so first, you’ll have to get through the sacroiliac joint.

Anatomy of Sacroiliac Joint 

The sacroiliac joint forms between the ilium and the sacrum bone, joined by many strong ligaments. It is a type of synovial joint. There are two sacroiliac joints in the human body, one on the left side and the other on the right side. They often match each other but vary from person to person. In the sacroiliac, joint two types of movement occur known as nutation and counternutation.

Purpose of Standing Flexion Test

The purpose of the standing flexion test is to assess the sacroiliac joint dysfunction, mainly the hypomobility (reduced mobility) in the sacroiliac joint. This condition may result from many different causes, such as gait issues (scoliosis or leg length discrepancy), osteoarthritis, pregnancy, injury, etc.

A positive standing flexion test will indicate reduced mobility in the affected sacroiliac joint (either left or right). The reduced mobility will be noticeable while performing the standing flexion test.

How to perform the test (Technique)

To perform this test, first, you must know the position of the patient and the examiner (therapist)

Position of the patient  – The patients stand erect.

Position of the examiner – The examiner (therapist) squats or stands behind the patient.

• After that, the examiner palpates both the PSIS simultaneously by placing his left hand’s thumb on the left PSIS and right hand’s thumb on the right PSIS.
• The patient then bend forwards as far as possible towards the midline while maintaining the knees extended.
• The examiner then looks at each PSIS movement and evaluates whether the movement of both PSIS is symmetrical or asymmetrical, as each PSIS should move symmetrically (in equivalent quantity) in a superior direction. 
• The test is negative when both the PSIS moves symmetrically in a superior direction.

• The test is positive when one PSIS moves more (further cranially) than the other PSIS in a superior direction. For example, if the right thumb starts to move forward early compared to the left thumb, it indicates right side sacroiliac dysfunction.

Reason for hypomobility 

The side that moves further cranially is the affected side (hypomobile side). Therefore, the reason for this hypomobility is that an articular restriction between the sacrum and ilium occurs (SIJ). Due to this articular restriction, less nutation will occur in the affected sacroiliac joint.

In the sacroiliac joint, we consider the movement of the sacrum. There are two movements of the sacrum nutation and counternutation. In nutation, the sacrum moves forward and downward. At the same time, the ilium moves in the opposite direction. Bodyweight causes the forward and downward bending of the sacrum, while the force from the floor coming up through the legs induces the ilium to move backward and downward.

As there will be less nutation, so the sacrum movement will get affected (reduced mobility). Therefore the ilium, including the PSIS on the hypermobile side, will move earlier.

Clinical evidence and Diagnostic accuracy

The standing forward flexion test has reliability and validity, with a sensitivity of 17% and specificity of 79%. Most studies have found that the reliability and validity of this test are relatively low for the diagnosis of sacroiliac joint dysfunction.

The standing flexion test is used to assess sacroiliac joint dysfunction. But due to lower reliability and validity, the use of this test in clinical practice remains questionable as it has to undergo additional research.

As there are many tests available, the clinical assessment of sacroiliac joint dysfunction is still controversial. Cibulka et al. (1988) investigated the reliability of a combination of four palpation evaluations for its discovery of SIJ dysfunction. The authors conclude that combining and performing the standing flexion test, the supine long sitting test, and palpation of the posterior superior iliac spine heights when sitting, and the prone knee flexion test allows the examiner to detect the existence of SIJ dysfunction.

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