The hip joint is a ball-in-socket joint where the ball or head of the femur (thigh bone) joins the pelvis at the socket called the acetabulum.
The hip is essentially a ball and socket joint, linking the "ball" at the head of the thigh bone (femur) with the cup-shaped "socket" in the pelvic bone. A total hip prosthesis is surgically implanted to replace the damaged bone within the hip joint. The surgeon will decide which type of implant and implant material - metal, plastic or ceramic - will work best for their patient.
Total hip prosthesis consists of three parts:
- A cup that replaces your hip socket.
- A ball that will replace the fractured head of the femur.
- A metal stem that is attached to the shaft of the bone to add stability to the prosthesis.
If the surgery is a "hemi-arthroplasty," the only bone replaced with a prosthetic device is the head of the femur.
Patients receive an extensive pre-operative evaluation of their hip to determine if they are a candidate for a hip replacement procedure. Their health care provider will assess the degree of disability, impact on their lifestyle, and pre-existing medical conditions. The health care provider will also evaluate their heart and lung function.
The surgery will be performed using general or spinal anesthesia. The orthopedic surgeon makes an incision, often over the buttocks, to expose the hip joint. The head of the femur is then surgically removed. Then, the hip socket is cleaned out and a tool called a reamer removes all of the remaining cartilage and arthritic bone.
The new socket is implanted, after which the metal stem is inserted into the femur. The artificial components are fixed in place, sometimes with special cement. The muscles and tendons are then replaced against the bones and the incision is closed.
What to Expect After Surgery
Patients return from surgery with a large dressing on the hip area. A small drainage tube may be placed during surgery to help drain excess fluids from the joint area. Many surgeons also place a knee immobilizer or special pillow between the legs in the operating room to prevent the hip from dislocating.
Patients experience moderate to severe pain after surgery. However, they may receive patient-controlled analgesia (PCA), intravenous (IV) analgesics or epidural analgesics to control the pain for the first couple of days after surgery. The pain should gradually decrease, and by the first day after surgery, oral analgesic medications may be sufficient to control pain. It is important to control the pain enough to enable patients to participate in physical therapy. Nurses administer pain medications about one-half hour prior to therapy so patients are comfortable during the therapy session.
Patients return from surgery with several IV lines in place to provide fluids and nutrition. The IV remains in place until the patient is drinking adequate amounts of fluids.
Sometimes, the blood that is drained from the wound during surgery is collected in a special sterile container to be re-infused through an IV after surgery.
Patients also return from surgery wearing AVI foot pumps. These devices are used to reduce the risk of developing blood clots, which are more common after leg surgery.
Patients should start moving and walking early after surgery. On the first day after surgery, patients may begin therapy if directed by their physician. When in bed, patients should perform ankle exercises frequently to prevent development of blood clots.
Patients are instructed on how to use an incentive spirometry device (a plastic device to encourage deep breathing), and cough and deep breathing exercises to gradually increase the depth of breaths in order to prevent lung collapse and pneumonia.
A Foley catheter is inserted during surgery to monitor kidney function and hydration level. This is typically removed on the first day after surgery. Patients are encouraged to try to walk to the bathroom with assistance.
With today's modern, less invasive surgical techniques, the goal of joint replacement is to speed recovery and help patients return to their normal, productive lives as soon as possible. Patients should talk to their surgeon about what kind of recovery they can anticipate. Permitted activities and rate of recovery depend on the type of condition the patient had prior to surgery and the surgical method that was performed.
Patients typically remain in the hospital for 2 to 4 days after surgery. However, some patients may need to stay temporarily at a rehabilitation unit or long-term care center until mobility has improved and they are safely able to live independently. These centers provide intensive physical therapy to assist patients in regaining muscle strength and flexibility in the joint.
Patients should be careful after surgery to not dislocate the prosthesis. The new hip will not have the same range of movement of the original joint, although patients should eventually be able to return to their previous level of activity. While patients should avoid vigorous sports such as skiing, or contact sports, many people go on to play tennis and golf quite successfully.
The use of crutches or a walker may be necessary for as long as three months, although most people who did not use them before are able to walk without them in several weeks.
Many surgeons place their patients on blood thinners for several weeks after surgery to help prevent blood clots. These may be taken in the form of pills (either Coumadin or aspirin) or injections.
The new joint has a limited range of movement. Patients need to take special precautions to avoid displacement of the joint. Most precautions are temporary, but some are more permanent. Patients should discuss precautions with their surgeon. In general, patients who have undergone total hip replacement should abide by the following guidelines:
- Avoid crossing their legs or ankles even when sitting, standing, or lying.
- When sitting, feet should be kept about 6 inches apart.
- When sitting, knees should be kept below the level of the hips. Avoid chairs that are too low and sit on a pillow to keep the hips higher than the knees.
- When getting up from a chair, slide toward the edge of the chair and then use a walker or crutches for support.
- Avoid bending over at the waist. Consider purchasing a long-handled shoehorn or a sock aid to assist in putting shoes and socks on without bending over. Also, an extension reacher or grabber may be helpful for picking up objects that are too low to reach.
- When lying in bed, place a pillow between the legs to keep the joint in proper alignment.
- A special abductor pillow or splint may be used to keep the hip in correct alignment.
- An elevated toilet seat may be necessary to keep the knees lower than the hips when sitting on the toilet.
The results of hip prosthesis surgery are usually excellent. The operation relieves pain and stiffness, and most patients (more than 80 percent) need no help walking. Implants need to be checked with an X-ray every two to three years to establish normal wear patterns. Modern implants are designed to be repaired. Repairing the implant is a much less serious surgery than complete revision to a new prosthesis but must be done before there is any damage to the bone or possible loosening of the fixation of the implant.
The indications for the replacement of the hip joint include:
- Hip pain that has failed to respond to conservative therapy (NSAID medication for 6 months or more)
- Hip osteoarthritis or arthritis confirmed by X-ray
- Inability to work, sleep, or move because of hip pain
- Loose hip prosthesis
- Some hip fractures
- Hip joint tumors
This surgery is not recommended for:
- Current hip infection
- Poor skin coverage around hip
- Paralysis of the quadriceps muscles
- Severe disease of the blood vessels of the leg and foot (peripheral vascular disease)
- Nerve disease (neuropathy) affecting the hip
- Severe limiting mental dysfunction
- Serious physical disease (terminal disease, such as metastatic disease)
- Morbid obesity (more than 300 pounds)
Please note that obesity always complicates hip replacement surgery. Obese patients should discuss their options with their surgeon.
Potential risks associated with total hip replacement include:
- Blood clots in the legs (deep vein thrombosis), which can dislodge and move to the lungs (pulmonary embolus)
- Infection that requires removal of the prosthesis
- Prosthesis dislocation
- Heterotopic bone formation (extra bone growth that can cause stiffness)
People who have a prosthetic device (such as an artificial joint) need to take special precautions against infection. They should carry a medical identification card indicating that they have a prosthetic device. Also, they should always inform their health care provider of their prosthetic hip joint. They should receive antibiotics prior to dental work or any invasive procedure.