Protrusio acetabuli – the cool way of saying acetabular protrusion. Refers to the inward bulging of the acetabulum into the pelvis usually with resultant over-covering of the femoral head. The deformity may be due to trauma but in many cases it is a sign of an underlying disease such as rheumatoid arthritis, ankylosing spondylitis, rickets, Paget’s disease and osteogenesis imperfecta. The above patient had Marfan syndrome.
