Pinned arthritic hip. Artwork of a hip with a pinned femur (thigh bone). This sort of pinning occurs after an osteotomy, a procedure used to treat osteoarthritis of the hip. The femur is cut in two just below its head (centre left) and the two ends are realigned. The operation allows weight to be carried through a different, largely undamaged, portion of the articular cartilage, thus reducing pain and disability in the joint. Osteoarthritis is a degenerative joint disease that results in the loss of cartilage between the joint and the growth of bone in place of the cartilage.