The surgery is extensive. It involves removing the joint – the damaged bone and cartilage – and replacing it with prosthetic parts made of metal, plastic or ceramics. Typically, surgeons enter the joint from the rear, which requires cutting through muscle and cartilage. But a relatively new procedure enables surgeons to enter from the front and only stretch the muscles aside, avoiding the cutting and minimizing pain and recovery time. Those who use this anterior technique say the benefits are substantial.