A Guide to Total Knee Replacement

Total knee replacement is now arguably the most successful surgical procedure in orthopaedics. It produces a prosthetic joint which closely approximates normal anatomic functions and is relatively painless. More importantly, it allows a return to activity and a freedom from limitation which are most ratifying to patients, families, and surgeons alike. Indeed, while the concept of acquiring an artificial knee joint may be intimidating to some individuals, it is one of the safest and most effective medical procedures to maintain the freedom from pain and personal independence so critical to us all.

The most common cause for knee replacement is arthritis. Arthritis is an inflammation of the joint that can cause pain, swelling, stiffness, instability and deformity of the knee. Avascular necrosis is also another cause for knee replacement. This is were a small portion of the bone does not get an adequate blood supply resulting in bone damage in that area. This results in sudden and severe onset of pain.

First, conservative treatment of arthritis and avascular necrosis is considered, not surgical intervention. Conservative treatment can be effective in the early stages of both arthritis and avascular necrosis. Minimizing weight bearing by using a cane, crutches or a walker will help improve the discomfort in the joint. It can also be relieved with the use of anti-inflammatory medication, cortisone injections and/or physical therapy. These interventions may relieve the pain temporarily or in some cases permanently.

What is a total knee replacement?

Your knee joint functions very much like a hinge at the junction of two bones, the femur and the tibia. The ends of the bones are covered with a thick cushion of hard, white cartilage. You are given only one coating of this cartilage in your lifetime. If it is damaged or worn away, the underlying bones rub together, producing the pain and inflammation characteristic of arthritis.

“Arthritis” simply means an inflammation of a joint causing pain, swelling, stiffness, instability and often deformity. Severe arthritis interferes with a person’s activities and limits his or her lifestyle.

The primary indication for a total knee replacement is to relieve pain. It may also help to restore motion, straighten the limb, improve stability, and improve the function of the joint

In total knee replacement, only the surface of the joint is removed, and a variety of artificial implants are substituted to produce an almost normal prosthetic joint.

This is accomplished by surgically shaving off the arthritic ends of the bones and replacing them with new metal and plastic surfaces. In reality, this is a “ resurfacing of the joint” and the supporting ligaments, tendons and muscles are retained. The parts which are surgically implanted mimic the normal anatomy they replace.

Which patients should have knee replacement?

The most common and compelling reason for a total knee replacement is arthritic pain. It need not be excruciation at any particular time, but often is chronic and disabling. Pain cannot be measured, and the degree of pain sufficient to justify surgery should be decided by the patient and the doctor together.

Painful and arthritic knees often become unstable and untrustworthy, causing falls and other injuries, as well as undermining he patient’s confidence. Climbing stairs, rising from chairs, and extended walking become a challenge. The patient’s independence and self-determination are compromised, and the quality of their life will deteriorate.

While most arthritic knees are the result of degenerative or osteoarthritis, other conditions such as rheumatoid arthritis, trauma, prior surgeries, contractures, instability and tumors can be relieved by total knee replacement.

What is the short-term prognosis for total knee replacement?

The short-term prognosis of total knee replacement is excellent. Most patients stand the morning after surgery and begin motion exercise that day. They can walk with confidence, climb stairs, and ride in a car by the time of the hospital discharge, although usually with the support of walkers, crutches, or canes. Physical therapy and motion exercises are the key to a good outcome, and these should continue for months. Some swelling, aching, and numbness are normal during this period with numbness and swelling lasting for up to six months.

The key to a good result is active participation in your physical therapy as well as your home exercise program. The most apparent benefit from total knee replacement is pain relief. In general, it takes most patients any where from three to six months to recover and experience pain relief and improvement in function. However, improvements can be realized for over a year after surgery.

What is the long-term prognosis for total knee replacement?

The long-term prognosis for total knee replacement is superlative, exceeding all other arthroplasties. The patient with a well-performed knee replacement should expect a greater than 90% chance of success at ten years, and a better than 80% chance that their joint will be in place and functioning well at twenty years. The patient himself can influence these odds through weight control, exercise, using antibiotic “prophyllaxis" (protection) from infection, and the avoidance of impact sports.

Benefits of Knee Replacement

The most apparent benefit is pain relief. In general, most patients take six weeks to three months to recover and experience pain relief and improvement in function. However, improvements can be realized for over a year after surgery.

Complications

The common complications of total knee surgery can now be largely avoided. Each patient receives a thorough preoperative medical evaluation by an internist as well as routine pre-admission testing. Auto-transfusion, or the donation of one’s own blood prior to surgery, can eliminate the problems of blood borne disease completely.

While phlebitis (or inflammation of the leg veins) is not rare, the incidence of fatal pulmonary emboli (or blood clots to the lungs) has been almost totally eliminated with the use of support stocking, knee motion machines, early ambulation, and blood thinning medication such as Coumadin.

Infection in a total knee replacement can be devastating. Like the other early complications, it is better avoided than treated. Thanks to the special antibiotics, expeditious surgery, and a full suite of sterile germ-free operating rooms, the infection rate at our institution is among the lowest in the world, at two to three cases per thousand patients.

Long-term complications such as wear, stiffness, or loosening of the parts relate as much to patient behavior as to surgical success. Nonetheless, these problem knees can usually be improved through revisional surgical procedures.

PREPARING FOR YOUR OPERATION

1. Betadine showers are advised twice daily for two weeks before surgery to lower the bacteria count of the skin. You can obtain Betadine Skin Cleanser from most pharmacies without a prescriptioin.

2. Multiple vitamins are advised, one daily for two weeks before surgery.

3. Discontinue aspirin and anti-inflammatory drugs two weeks before surgery. For example: Motrin, Advil, Voltaren, etc.

4. One unit of blood can be donated prior to your operation and can be stored at the hospital where you are having your surgery. In the event that you are unable to donate your own blood for surgery, there are other options available including donor directed from a family member or a friend with the same blood type.

5. Patients engaging in the auto-transfusion program will need to take supplemental iron tablets beginning one week prior to their first blood donation. Iron can be purchased without a prescription.

6. Have your dentist check your teeth for infection prior to surgery. Do this as soon as possible after scheduling your surgery (and 72 hours prior to donation of blood for surgery).

7. Ask to speak with the Surgical Schedulers and/or the Orthopaedic Nurse to assist in planning and answering questions.

8. Pre- and post-operative instructions will be reviewed by the Orthopaedic Nursing Staff.

9. Your discharge plan from the hospital will also be reviewed by the Orthopaedic Social Worker and Home Care Department prior to the operation

10. A complete medical evaluation (and all the necessary preoperative lab studies) will be performed by a member of the Department of Internal Medicine and a Cardiologist prior to surgery.

11. The Department of Physical Therapy will instruct you in the use of a walker and crutches. Isometric exercises will be demonstrated to help you maintain muscular strength during the postoperative period. Arm exercises are also important prior to coming into the hospital to strengthen your upper extremities to prepare for using crutches and a walker.

TWENTY-FOUR HOURS BEFORE SURGERY

1. Absolutely nothing should be taken by mouth to eat or drink after midnight on the night before surgery. It is absolutely essential that your stomach be completely empty at the time of your operation.

2. Your knee will be shaved and scrubbed by an OR technician prior to the operation to ensure cleanliness.

3. Antibiotic medications will be started just prior to surgery and continued after the operation intravenously.

4. You will be taken to the operating room approximately sixty minutes before the scheduled time of your surgery. You will be asked to wear a hospital gown and to remove any jewelry as well as dentures or wigs. Your valuables should be left at home or with your family. If this is not possible, please leave them with the nursing staff they will secure in the security office.

5. You will receive preoperative medications by injection to help you relax and be more comfortable during preparations for your surgery.

6. You will be transported to the operating room on a stretcher or bed. There you will meet the Anesthesiologist who will start intravenous fluid in your arm. You will then be given medication to put you to sleep once you are in the operating room. There are a wide variety of techniques used for anesthesia , all of which prevent pain during the surgical procedure. If you wish, it is even possible to be awake during your surgery.

AFTER SURGERY

1. You will be in the recovery room in your bed with your knee cushioned in an electronic cradle (C.P.M). This cradle will help your with your physical therapy by slowly increasing the motion of your knee throughout your hospital stay. There may be exceptions to the placement of the C.P.M. depending on your type of surgery.

2. You will be in your bed, on your back, on a special orthopaedic mattress to prevent skin irritation.

3. Intravenous fluids, blood transfusions, and antibiotics are often given for the first two post-operative days. You may eat and drink as you are able to tolerate liquids and food.

4. The nurses and orthopaedic team will show you how to move in bed, how to use a bedpan, and how to exercise your legs.

5. Several measures are taken to prevent thrombophlebitis. Coumadin (or aspirin) is administered to thin the blood and prevent blood clots from forming. This will be prescribed for six weeks after surgery. Early ambulation and shifting positions in bed are also important for circulation and to prevent complications.

6. There is a surgical dressing present for two days after surgery. There may be several small tubes that are used for drainage at the operative site. These are also removed two days after surgery. The wound will be cleaned twice daily by the nursing staff.

7. Exercises to strengthen the arms and legs, and to encourage circulation, are performed throughout the postoperative period.