Dual-mobility articulation concept In 1974 Professor Bousquet developed the dual-mobility (DM) hip articulation concept to reduce wear, restore near-normal motion-range in the hip joint, and at the same time increase hip prosthesis stability. The dual-mobility hip articulation design consist of a large non-fixed polyethylene liner sliding freely within the metal cup-shell which is fixed into the bone, and inside the mobile liner is a second articulation with a small femoral head. The dual-articulation of the prosthetic joint prevents impingement of the femoral neck on the acetabular rim of the implant. Studies have shown that dual-mobility hip prostheses have good survival rates and reduces dislocation rates both in patients with primary osteoarthritis of the hip and a lesser compliant patient group with displaced femoral neck fractures . Clinical expectations for the dual-mobility articulation concept for treatment of displaced medial FNF are good; however, there are only a few publications available and there are no studies of implant fixation / cup migration. It is important to study both the dislocation risk as well as the mechanical stability of the bony fixation since the advantage of a low dislocation rate would be meaningless if the cups were to loosen mechanically from the surrounding bone in the mid- or longer term.