A medical device for implantation in a hip joint of a patient, the medical device comprising a prosthetic caput femur (819) comprising: a spherical portion adapted to be received in an acetabulum or a prosthetic acetabulum (65) fixated to the pelvic bone (9) of the patient. The medical device further comprises a releasing member (820) adapted to restrain the spherical portion in the acetabulum or the prosthetic acetabulum. The releasing member is further adapted to release the spherical portion from the acetabulum or the prosthetic acetabulum, when a strain, exceeding a predetermined threshold, is exerted on the hip joint, thereby releasing the prosthetic caput femur from the acetabulum or prosthetic acetabulum.
