Anterior Total Hip Replacement
What is total hip replacement?
The hip joint is a ball and socket joint. Hip arthritis develops when the cartilage between the two parts wears out so that the joint is "bone-on-bone" (see left x-ray above). Total hip replacement involves making an incision down to the joint, removing the arthritic portions of the hip joint, and inserting metal and plastic implants. Special instruments are used to shape the bones to fit the implants. The components are usually put in without using bone cement because the implants are coated to promote bone to grow into the metal parts for long term fixation. The parts of a hip replacement include the cup, the stem, the ball, and the liner (see image on FAQs page). The cup and stem are always made of metal, the ball can be either metal or ceramic, and the liner is usually plastic. When both the ball and liner are metal the hip replacement is considered metal-on-metal. This combination has some benefits but is done less commonly now because some patients have an adverse reaction to the metal-on-metal bearing surface. The goals of total hip replacement surgery are to take away the hip pain associated with hip arthritis, to increase a patient's mobility, and make a stable joint that recreates the patient's normal hip biomechanics. It is one of the most successful procedures in all of medicine with the vast majority of patients experiencing near complete or complete hip pain relief for 20 years or longer.
What is anterior total hip replacement?
Direct anterior total hip replacement is a way of doing hip replacement that has become popular recently amongst both patients and surgeons. It has become more popular because of the increasing availability of the Hana® operating table. The Hana® table allows for unique positioning of the hip that makes the anterior approach more facile for the surgeon. The incision is made on the front of the hip instead of on the side (lateral) or in the back (posterior). It allows the surgery to be done by going in-between the muscles rather than cutting through them. The potential advantages of the anterior approach include quicker recovery, less pain, lower dislocation rate, no required hip precautions, and easier ability to check leg lengths and hip offset to better recreate normal hip biomechanics. Patients typically require less time in the hospital postoperatively because of the quicker recovery.
Posterior approach total hip replacement is the most common way for hip replacements to be performed in the United States. This approach requires splitting the gluteus maximus muscle as well as incising the tendons of the short external rotator muscles in the back of the hip. Because of the muscles and tendons that are disrupted, the recovery process can be slower and hip precautions are usually necessary postoperatively to prevent hip dislocation. This is why most patients after total hip replacement cannot cross their legs, cannot sit in low chairs, and have to be careful how they bend over to prevent dislocation. These hip precautions are not necessary after anterior total hip replacement.