Gaenslen's test is a medical diagnostic technique performed on the lower back to help determine if an individual is suffering from sacroiliac joint dysfunction. There are a variety of synonyms for this test, including the Pelvic Compression Test, the Sacroiliac Joint Stress Test, and the Lower Limb Tension Test. These tests involve manipulating the legs and lower back to see if certain movements cause pain or discomfort, with the results helping doctors and other healthcare professionals assess the extent of a patient's condition. While different names may be used for this test, they all serve the same purpose of helping to diagnose sacroiliac joint dysfunction and similar conditions.