Drehmann sign

The Drehmann sign describes a clinical test of examining orthopedic patients and is widely used in the functional check of the hip joint. It was first described by Gustav Drehmann (Breslau, 1869-1932).

The Drehmann sign is positive if an unavoidable passive external rotation of the hip occurs when performing a hip flexion. In addition, an internal rotation of the respective hip joint is either not possible or accompanied by pain when forcefully induced.

The positive Drehmann sign is a typical clinical feature in slipped capital femoral epiphysis (SCFE), the impingement syndrome, Legg–Calvé–Perthes disease or in osteoarthritis of the hip joint.

...
Wikipedia