Protrusio acetabuli is an uncommon defect of the acetabulum, the socket that receives the femoral head to make the hip joint.
Limitation of joint range of movement is the earliest sign, along with pain.
Protrusio acetabuli is divided into two types, primary and secondary.
Protrusio acetabuli may also be thought of as unilateral or bilateral.
The protrusio may progress until the femoral neck impinges against the pelvis.