Yeoman's test in a physical exam is performed to determine if a person has sacroiliitis

Sacroiliitis

In medicine, sacroiliitis is an inflammation of the sacroiliac joint. Sacroiliitis is a feature of spondylarthropathies .-External links:*...

. With the subject prone, the test is performed by rotating the ilium

Ilium (bone)

The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...

 with one hand and extending the hip while the knee

Knee

The knee joint joins the thigh with the leg and consists of two articulations: one between the fibula and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a mobile trocho-ginglymus , which permits flexion and extension as...

 is extended. Pain over the ipsilateral posterior sacroiliac joint

Sacroiliac joint

The sacroiliac joint or SI joint is the joint in the bony pelvis between the sacrum and the ilium of the pelvis, which are joined together by strong ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side...

area is indicative of sacroiliitis.

Also tests for S/I joint sprain / strain.

• Picture demonstrating Yeoman's test