A medical device for treating hip joint osteoarthritis in a human patient by providing at least one artificial hip joint surface is disclosed. The medical device comprises a prosthetic part (98) or a bone plug (31) adapted to be placed in a hole (18) in the pelvic bone such that a concave interior surface of the prosthetic part or the bone plug is facing in a direction towards the caput femur, and a supporting member (95； 99) connected to said prosthetic part or bone plug. The prosthetic part or the bone plug is adapted to be inserted into said hole from the abdominal side of the acetabulum and oriented, during the insertion, such that the concave interior surface is facing in the direction towards the caput femur. The supporting member is adapted to be positioned on the acetabulum side of the pelvic bone to fixate the prosthetic part or bone plug to a surface arranged on the acetabulum side of the pelvic bone, when implanted. The medical device comprises at least one of: an artificial caput femur surface (45), wherein a largest cross-sectional distance of said artificial caput femur surface is smaller than said hole, such that said artificial caput femur surface can pass through said hole； and an artificial acetabulum surface (65), wherein a largest cross-sectional distance of said artificial acetabulum surface is smaller than said hole, such that said artificial acetabulum surface can pass through said hole.
