Hip joint device and method

A medical device for implantation in a hip joint of a patient, wherein said medical device is adapted to be fixated to a pelvic bone of the patient, and wherein said medical device comprises an inner and an outer surface, wherein a contacting portion of said inner surface is spherical and adapted to face a centre of the hip joint when said medical device is implanted, and wherein said medical device is adapted to receive a caput femur or a prosthetic caput femur having a spherical portion, wherein

• a) said medical device comprises at least one extending portion adapted to clasp the caput femur, or prosthetic caput femur, for restraining said caput femur, or said prosthetic caput femur in said medical device, and wherein
• b) said medical device is adapted to release the caput femur or prosthetic caput femur from said medical device when a predetermined strain is placed on said medical device.