Shriners Hospitals for Children, Honolulu, HI, USA. samuel.vandevelde@student.kuleuven.ac.be
Protrusio acetabuli is a hip joint deformity in which the medial wall of the acetabulum invades into the pelvic cavity, with associated medial displacement of the femoral head. The gradual deepening of the acetabular cavity is caused by primary idiopathic and secondary neoplastic, infectious, metabolic, inflammatory, traumatic, and genetic disorders. Due to this variety of causes, there was a considerable speculation regarding the aetiology of the hip deformity in the early literature.