The list from least invasive to most invasive are femoral head, triple pelvic osteotomy, and total hip replacement. Femoral head is a process where the vet goes in, cuts off the tops of the ball from the ball and socket joint on the femor bone and finishes. The trick to this surgery is the rehabiliation. Through excercise, the muscles develop around the joint and take over all the action. Essentially there is no longer any hip joint.
Nothing is connected besides the muscles around the hip.
Also, the bones will no longer rub against each other so they will never get arthritis in that area later on in life. Other pluses are that no foreign materials like implants or cement are used so the likelihood of infection is less. The negative of the surgery is the time needed to exercise the dog after the surgery. Walks with a sling under the belly, and hip extension exercises while held down are very intensive for at least 6-10 weeks after the surgery. Continued excercise will help and increase the muscles more every day.