A medical device for implantation in a hip joint of a patient is provided. The medical device is adapted to be fixated to the pelvic bone of the patient. The medical device comprises an inner and an outer surface, a contacting portion of the inner surface is spherical and adapted to face the center of the hip joint when said medical device is implanted, and said medical device is adapted to receive a caput femur or a prosthetic caput femur having a spherical portion. The medical device comprises at least one extending portion adapted to clasp the caput femur, or prosthetic caput femur, for restraining said caput femur, or prosthetic caput femur in said medical device. The medical device is adapted to release the caput femur or prosthetic caput femur from the medical device when a predetermined strain is placed on the medical device.