The Gillet test is a commonly used physical examination technique that medical professionals use to evaluate the mobility of the sacroiliac joint. It involves palpating and assessing the movement of the posterior superior iliac spine while the patient stands with their feet parallel to each other. Synonyms for the Gillet test include the Flexion Abduction External Rotation (FABER) test, Patrick's test, and the figure-four test. These tests have similar aims to assess the joint and identify any issues or conditions such as arthritis or inflammation that may be causing discomfort, affecting a patient's mobility or causing pain in the lower back, hips or legs.