A total hip replacement is a surgical procedure whereby the diseased cartilage and bone of the hip joint is surgically replaced with artificial materials. The normal hip joint is a ball and socket joint. The socket is a "cup-shaped" component of the pelvis called the acetabulum. The ball is the head of the thighbone (femur). Total hip joint replacement involves surgical removal of the diseased ball and socket and replacing them with a metal (or ceramic) ball and stem inserted into the femur bone and an artificial plastic (or ceramic) cup socket.
The metallic artificial ball and stem are referred to as the "femoral prosthesis" and the plastic cup socket is the "acetabular prosthesis." Upon inserting the prosthesis into the central core of the femur, it is fixed with a bony cement called methylmethacrylate. Alternatively, a "cementless" prosthesis is used that has microscopic pores which allow bony ingrowth from the normal femur into the prosthesis stem. This "cementless" hip is felt to have a longer duration and is considered especially for younger patients. Total hip replacement is also referred to as total hip arthroplasty.
When a hip replacement is needed
Hip replacement surgery is usually necessary when the hip joint is worn or damaged to the extent that your mobility is reduced and you experience pain even while resting.
The most common reason for hip replacement surgery is osteoarthritis. Other conditions that can cause hip joint damage include:
• Rheumatoid arthritis
• Hip fracture
• Septic arthritis
• Ankylosing spondylitis
• Disorders that cause unusual bone growth (bone dysplasias)
Who is offered hip replacement surgery
A hip replacement is major surgery, so is normally only recommended if other treatments, such as physiotherapy or steroidinjections, haven't helped reduce pain or improve mobility.
You may be offered hip replacement surgery if:
• you have severe pain, swelling and stiffness in your hip joint and your mobility is reduced
• your hip pain is so severe that it interferes with your quality of life and sleep
• everyday tasks, such as shopping or getting out of the bath, are difficult or impossible
• you're feeling depressed because of the pain and lack of mobility
• you can't work or have a normal social life
You'll also need to be well enough to cope with both a major operation and the rehabilitation afterwards.
You will most likely be admitted to the hospital on the day of your surgery.
After admission, you will be evaluated by a member of the anesthesia team. The most common types of anesthesia are general anesthesia (you are put to sleep) or spinal, epidural, or regional nerve block anesthesia (you are awake but your body is numb from the waist down). The anesthesia team, with your input, will determine which type of anesthesia will be best for you.
Many different types of designs and materials are currently used in artificial hip joints. All of them consist of two basic components: the ball component (made of highly polished strong metal or ceramic material) and the socket component (a durable cup of plastic, ceramic or metal, which may have an outer metal shell).
The prosthetic components may be "press fit" into the bone to allow your bone to grow onto the components or they may be cemented into place. The decision to press fit or to cement the components is based on a number of factors, such as the quality and strength of your bone. A combination of a cemented stem and a non-cemented socket may also be used.
Your orthopaedic surgeon will choose the type of prosthesis that best meets your needs.
The surgical procedure takes a few hours. Your orthopaedic surgeon will remove the damaged cartilage and bone and then position new metal, plastic, or ceramic implants to restore the alignment and function of your hip.
After surgery, you will be moved to the recovery room where you will remain for several hours while your recovery from anesthesia is monitored. After you wake up, you will be taken to your hospital room.
Risks associated with hip replacement surgery may include:
• Blood clots. Clots can form in your leg veins after surgery. This can be dangerous because a piece of a clot can break off and travel to your lung, heart or rarely your brain. Your doctor may prescribe blood-thinning medications to reduce this risk.
• Infection. Infections can occur at the site of your incision and in the deeper tissue near your new hip. Most infections are treated with antibiotics, but a major infection near your prosthesis may require surgery to remove and replace the prosthesis.
• Fracture. During surgery, healthy portions of your hip joint may fracture. Sometimes the fractures are so small that they heal on their own, but larger fractures may need to be corrected with wires, pins, and possibly a metal plate or bone grafts.
• Dislocation. Certain positions can cause the ball of your new joint to become dislodged, particularly in the first few months after surgery. If the hip dislocates, your doctor may fit you with a brace to keep the hip in the correct position. If your hip keeps dislocating, surgery is often required to stabilize it.
• Change in leg length. Your surgeon takes steps to avoid the problem, but occasionally a new hip makes one leg longer or shorter than the other. Sometimes this is caused by a contracture of muscles surrounding the hip. In this case, progressively strengthening and stretching those muscles may help.
• Loosening. Although this complication is rare with newer implants, your new joint may not become solidly fixed to your bone or may loosen over time, causing pain in your hip. Surgery might be needed to fix the problem.
Need for second hip replacement
Your prosthetic hip joint may wear out eventually, so if you have hip replacement surgery when you're relatively young and active, you eventually may need a second hip replacement. However, new materials are making implants last longer, so a second replacement may not be needed.
Most artificial hip joints have a polished metal or ceramic ball that fits into a cup liner that's made of very hard plastic. Some older types of prostheses used mainly in the last decade use a metal cup liner, which may last longer but can cause other problems. Metal-on-metal prostheses are more likely to release metal ions into your bloodstream, which can cause inflammation and bone erosion. Because of these concerns, metal-on-metal prostheses are now rarely used.
What you can expect
When you check in for your surgery, you'll be asked to remove your clothes and put on a hospital gown. You'll be given either a general anesthetic or a spinal block, which numbs the lower half of your body.
During the procedure
To perform a hip replacement, your surgeon:
• Makes an incision over the front or side of your hip, through the layers of tissue
• Removes diseased and damaged bone and cartilage, leaving healthy bone intact
• Implants the prosthetic socket into your pelvic bone, to replace the damaged socket
• Replaces the round ball on the top of your femur with the prosthetic ball, which is attached to a stem that fits into your thighbone
Techniques for hip replacement are evolving. As surgeons continue to develop less invasive surgical techniques, these techniques might reduce recovery time and pain.
After the procedure
After surgery, you'll be moved to a recovery area for a few hours while your anesthesia wears off. Medical staff will monitor your blood pressure, pulse, alertness, pain or comfort level, and your need for medications.
Blood clot prevention
After your surgery, you'll be at increased risk of blood clots in your legs. Possible measures to prevent this complication include:
• Early mobilization. You'll be encouraged to sit up and even try walking with crutches or a walker soon after surgery. This will likely happen the same day as your surgery or on the following day.
• Pressure application. Both during and after surgery, you may wear elastic compression stockings or inflatable air sleeves similar to a blood pressure cuff on your lower legs. The pressure exerted by the inflated sleeves helps keep blood from pooling in the leg veins, reducing the chance that clots will form.
• Blood-thinning medication. Your surgeon may prescribe an injected or oral blood thinner after surgery. Depending on how soon you walk, how active you are and your overall risk of blood clots, you may need blood thinners for several more weeks after surgery.
A physical therapist may help you with some exercises that you can do in the hospital and at home to speed recovery.
Activity and exercise must be a regular part of your day to regain the use of your joint and muscles. Your physical therapist will recommend strengthening and mobility exercises and will help you learn how to use a walking aid, such as a walker, a cane or crutches. As therapy progresses, you'll usually increase the weight you put on your leg until you're able to walk without assistance.
Home recovery and follow-up care
Before you leave the hospital, you and your caregivers will get tips on caring for your new hip. For a smooth transition:
• Arrange to have a friend or relative prepare some meals for you
• Place everyday items at waist level, so you can avoid having to bend down or reach up
• Consider making some modifications to your home, such as getting a raised toilet seat if you have an usually low toilet
Six to 12 weeks after surgery, you'll have a follow-up appointment with your surgeon to make sure your hip is healing properly. If recovery is progressing well, most people resume their normal activities by this time — even if in a limited fashion. Further recovery with improving strength will often occur for six to 12 months.
Is Hip Replacement Surgery Safe?
Hip replacements surgery has been performed for years and surgical techniques are being improved all the time. As with any surgery, however, there are risks. Since you will not be able to move around much at first, blood clots are a particular concern. Your doctor will give you blood thinners to help prevent blood clots from occurring. Infection and bleeding are also possible, as are risks associated with using general anesthesia.
Other less common concerns that you and your doctor must watch out for are:
• Your legs may not be of equal length after the surgery.
• You must be careful not to cross your legs or not to sit too low because the joint may be dislocated.
• Pieces of fat in the bone marrow may become loose, enter the bloodstream and get into the lungs, which can cause very serious breathing problems.
• Nerves in the hip area may be injured from swelling or pressure and can cause some numbness.
• The replacement parts may become loose, break, or become infected.
Talk to your surgeon about these risks before undergoing the procedure.
How Long Will My New Joint Last After Hip Replacement Surgery?
When hip replacement surgeries were first performed in the early 1970s, it was thought that the average artificial joint would last approximately 10 years. We now know that about 85% of the hip joint implants will last 20 years. Improvements in surgical technique and artificial joint materials should make these implants last even longer. If the joint does become damaged, surgery to repair it can be successful but is more complicated than the original procedure.