KNEE REPLACEMENT AFTERCARE RISKS

Aftercare
Aftercare following knee replacement surgery begins while the patient is still in the hospital. Most patients will remain there for five to 10 days after the operation. During this period the patient will be given fluids and antibiotic medications intravenously to prevent infection. Medications for pain will be given every three to four hours, or through a device known as a PCA (patientcontrolled anesthesia). The PCA is a small pump that delivers a dose of medication into the IV when the patient pushes a button. To get the lungs back to normal functioning, a respiratory therapist will ask the patient to cough several times a day or breathe into blow bottles.

Aftercare during the hospital stay is also intended to lower the risk of a venous thromboembolism (VTE), or blood clot in the deep veins of the leg. Prevention of VTE involves medications to thin the blood; exercises for the feet and ankles while lying in bed; and wearing thromboembolic deterrent (TED) or deep vein thrombosis (DVT) stockings. TED stockings are made of nylon (usually white) and may be knee-length or thigh-length; they help to reduce the risk of a blood clot forming in the leg vein by putting mild pressure on the veins.

Physical therapy is also begun during the patient's hospital stay, often on the second day after the operation. The physical therapist will introduce the patient to using a cane or crutches and explain how to manage such activities as getting out of bed or showering without dislocating the new prosthesis. In most cases the patient will spend some time each day on a continuous passive motion (CPM) machine, which is a device that repeatedly bends and straightens the leg while the patient is lying in bed. In addition to increasing the patient’s level of physical activity each day, the physical therapist will help the patient select special equipment for recovery at home.

Commonly recommended devices include tongs or reachers for picking up objects without bending too far; a sock cone and special shoehorn; and bathing equipment. Following discharge from the hospital, the patient may go to a skilled nursing facility, rehabilitation center, or home. Patients who have had bilateral knee replacement are unlikely to be sent directly home. Ongoing physical therapy is the most important part of recovery for the first four to five months following surgery. Most HMOs in the United States allow home visits by a home health aide, visiting nurse, and physical therapist for three to four weeks after surgery. Some hospitals allow patients to borrow a CPM machine for use at home for a few weeks. The physical therapist will monitor the patient’s progress as well as suggest specific exercises to improve strength and range of motion. After the home visits, the patient is encouraged to take up other forms of low-impact physical activity in addition to the exercises; swimming, walking, and pedaling a stationary bicycle are all good ways to speed recovery. The patient may take a mild medication for pain (usually aspirin or ibuprofen) 30–45 minutes before an exercise session if needed.

The patient will be instructed to notify his or her dentist about the knee replacement so that extra precautions can be taken against infection resulting from bacteria getting into the bloodstream during dental work. Some surgeons ask patients to notify them whenever the dentist schedules a tooth extraction, root canal, or periodontal work.

Risks
Serious risks associated with TKR include the following:
• Loosening or dislocation of the prosthesis. The risk of dislocation varies, depending on the type of prosthesis used, the patient’s level of activity, and the previous condition of the knee joint.
• Deep vein thrombosis (DVT). There is some risk (about 1.5% in the United States) of a clot developing in the deep vein of the leg after knee replacement surgery because the blood supply to the leg is cut off by a tourniquet during the operation. The blood-thinning medications and TED stockings used after surgery are intended to minimize the risk of DVT.
• Infection. The risk of infection is minimized by storing autologous blood for transfusion and administering intravenous antibiotics after surgery. The rate of infection following knee replacement is about 1.89%. Factors that increase the risk of infection after TKR include poor nutritional status, diabetes, obesity, a weakened immune system, and a history of smoking.
• Heterotopic bone. Heterotopic bone is bone that develops at the lower end of the femur after knee replacement surgery. It is most likely to develop in patients whose knee joints developed an infection. Heterotopic bone can cause stiffness and pain, and usually requires revision surgery.

Normal results
Normal results include relief of chronic pain in the knee and greater range of motion in the knee joint. Realistically, however, the patient should not expect complete restoration of function in the knee, and will usually be advised to avoid contact sports, skiing, jogging, or other athletic activities that strain the knee joint.

Mild swelling of the leg may occur for as long as three to six months after surgery. It can be treated by elevating the leg, applying an ice pack, and wearing compression stockings.

One commonplace side effect of TKR is that knee prostheses sometimes set off metal detectors in airports and high-security buildings because of their large metal content. Patients who fly frequently or whose occupations require security clearance should ask their doctor for a wallet card certifying that they have a knee prosthesis. The patient can expect a cemented knee prosthesis to last about 10–15 years, although many still function well as long as 20 years later. Cementless prostheses have not been in use long enough for reliable evaluations of their long-term durability. When the prosthesis wears out or becomes loose, it is replaced in a procedure known as knee revision surgery.

Morbidity and mortality rates
A study published in 2002 reported that the 30-day mortality rate following total knee arthroplasty was 0.5%. The overall frequency of serious complications in this time period was 2.2%. This figure included 0.4% heart attack; 0.7% pulmonary embolism; and 1.5% deep venous thrombosis. The rate of complications was highest in patients over 70, and male patients were more likely to have heart attacks than women.

A 2001 study published by the Mayo Clinic reviewed the records of 22,540 patients who had had knee replacements between 1969 and 1997. The mortality rate within 30 days of surgery was 0.21%, or 47 patients. Forty-three of the 47 patients had had preexisting cardiovascular or lung disease. Patients who had had bilateral knee operations had a higher mortality rate than those who had not.

Alternatives
Nonsurgical alternatives
MEDICATION.
The most common conservative alternatives to knee replacement surgery are analgesics, or painkilling medications. Most patients who try medication for knee pain begin with an over-the-counter NSAID such as ibuprofen (Advil). If the pain cannot be controlled by nonprescription analgesics, the doctor may give the patient cortisone injections, which relieve the pain of arthritis by reducing inflammation. Unfortunately, the relief provided by cortisone tends to diminish with each injection; moreover, the drug can produce serious side effects.

If the knee pain is caused by rheumatoid arthritis, a group of medications known as disease-modifying antirheumatic drugs, or DMARDs, may help to slow or stop the progress of the disease. They work by suppressing or interfering with the immune system. DMARDs include such drugs as penicillamine, methotrexate, oral or injectable gold, hydroxychloroquine, leflunomide, and sulfasalazine. DMARDs are not suitable for all patients with RA, however, as they sometimes have serious side effects. In addition, some of them are slow-acting and may take several months to work before the patient feels some relief.

LIFESTYLE CHANGES.
A second alternative to knee surgery is lifestyle changes. Losing weight helps to reduce stress on the knee joint. Giving up specific sports or other activities that damage the knee, such as jogging, tennis, high-impact aerobics, or stair-climbing exercise machines, may control the pain enough to make surgery unnecessary. Wearing properly fitted shoes and avoiding high heels and other extreme styles can also help to control pain and minimize further damage to the knee.

BRACES AND ORTHOTICS.
Some patients with unstable knees are helped by functional braces or knee supports that are designed to keep the kneecap from slipping out of place. Orthotics, which are inserts placed inside shoes, are often helpful to patients whose knee problems are related to their gait. Orthotics are designed either to correct the position of the foot in order to keep it from turning too far outward or inward, or to correct problems in the arch of the foot. Some orthotics are made of soft material that cushions the foot and are particularly helpful for patients with osteoarthritis or diabetes.

Complementary and alternative
(CAM) approaches
Complementary and alternative therapies are not substitutes for arthroscopy or joint replacement surgery, but some have been shown to relieve physical pain before or after surgery, or to help patients cope more effectively with the emotional and psychological stress of a major operation. Acupuncture, chiropractic, hypnosis, and mindfulness meditation have been used successfully to relieve the pain of osteoarthritis as well as postoperative discomfort. According to Dr. Marc Darrow, author of The Knee Sourcebook, a plant extract called RA-1, which is used in Ayurvedic medicine to treat arthritis, relieved pain and leg swelling in patients participating in a randomized trial. Alternative approaches that have helped patients maintain a positive mental attitude include meditation, biofeedback, and various relaxation techniques.

Alternative surgical procedures
Arthroscopy is the most common surgical alternative to knee replacement. It should be understood, however, as a way to postpone TKR rather than avoid it completely. The arthroscopic procedure most often used to treat knee pain from osteoarthritis is debridement, in which the surgeon cuts or scrapes away damaged structures or tissues until healthy tissue is reached. Most patients who have had arthroscopic débridement have been able to postpone TKR for three to five years.

Cartilage transplantation is a procedure in which small bone plugs with cartilage are removed from a part of the patient’s knee where the cartilage is still healthy and transplanted to the area in which cartilage has been damaged. Another form of cartilage transplantation involves two operations, one to remove cartilage cells from the patient’s knee for culture in a laboratory, and a second operation to place the new cells within the damaged part of the knee. The cultured cells are covered with a thin layer of tissue to hold them in place. After surgery, the cartilage cells multiply to form new cartilage inside the knee. Unfortunately, as of 2003 neither form of cartilage transplantation is usually beneficial to patients with osteoarthritis; transplantation has been most successful in treating patients whose knee cartilage was damaged by sudden trauma rather than by gradual degeneration.