Common Questions About Total Hip Replacement
What happens during hip replacement surgery?
During hip replacement surgery, the worn out hip is removed and replaced with an artificial one made of metal parts. First, the surgeon opens the hip. The ball of the hip is then removed. The surgeon prepares the bone of the cup (or acetabulum) with a circular "cheese grater" type device called a reamer. A hemispherical metal cup is then wedged into the bone of the acetabulum. A liner, usually made of plastic, is placed inside the cup. Next, the surgeon prepares the bone of the femur with a set of drills, reamers and rasps. The stem is either wedged or cemented into the femur. A modular ball (or head) is affixed to the tope of the metal stem and the hip is reduced. When the surgeon assures that the correct size is in place to give both stability and correct leg length, the hip is closed.
What are the types of implants?
Many different companies made orthopaedic implants. Implants may either be press-fit (this allows the bone to grow into a rough surface of metal on the implant) or cemented (bone cement is used to attach the implant to bone). Both types of implant have high success rates. Initially, hip replacements were all cemented but now more are press-fit. Some patients may have deformities of the hip that may require one or the other type of implant. Ask your surgeon about your particular implant.
What is the bearing surface?
Your hip or knee used to have a smooth surface of cartilage. Your new hip will have a man-made surface called the bearing.
The most common bearing surface used is a metal ball and a plastic liner. Improvements have been made in the plastic liners to harden the plastic (a process known as cross-linking). The newer plastic liners are thought to wear better than the old ones.
Recently, other options have become available for the bearing surface. Each has pros and cons. Another bearing surface is ceramic head and liner. This surface has excellent wear; however, there is a very low rate of head breakage and of an audible squeak. A third option is a metal head and metal liner. The wear of this bearing is excellent and it allows for a larger size ball. The larger ball may reduce dislocation rates. However, the metal on metal surfaces release a very low level of metal ions into your blood. This may build up in your body's organs. While these metal ions are not thought to lead to complications or any risk of cancer, they are measurable. Hip resurfacing uses a metal on metal surface.
There may be limitations on the type of approach used (see below) depending on the bearing surface that is chosen. Please discuss bearing surface options with your doctor.
What "approach" is best for me?
Years ago, all hip replacements were done through a large incision. Today, depending on your surgeon and both the shape of your bones and your body, it may be possible to perform your replacement through a smaller incision, known as minimally invasive techniques. One way of doing a hip replacement is with two small incisions. With this approach, there are no hip precautions after surgery and less manipulation of the leg during surgery. An X-ray machine is used during surgery to help with correct placement of the hip replacement.
Please discuss the surgical approach with your doctor.
What results can I expect from my new hip?
We believe that 90 to 95 percent of patients have good to excellent results, even at ten years post hip replacement.
While hip replacement gives excellent pain relief, it does not give you a normal hip. Many patients are pain-free, but some still may have occasional aches and an awareness that it's not their "own" joint. Most patients can get back to activities; however, we do not recommend high impact activities or running after hip replacement. We do recommend golf, walking, weight lifting, doubles tennis, dancing, bicycling or swimming. More dangerous activities, such as horseback riding, skiing and waterskiing are possible, but do place your joint at some risk. A fall may cause the hip to dislocate or the bone to break around the implant. These activities are not recommended unless you already are at an advanced level.
John Hopkins University