Total knee replacement is now the preferred operation for many patients with arthritic involvement of the knee. The concepts of replacement of any joint in the body are the same, namely to replace the worn portions of the patient’s joint with man-made components which then serve to function as the patient’s own joint. The knee joint replacement uses the same basic principles and materials as when an arthritic hip is replaced.

Attempts at replacement of the knee joint date back to the mid-1960’s. There were in the early period many modifications of the prosthesis and the operative technique used to replace the knee. Since 1974 the technique and the prosthesis itself has remained generally unchanged except for minor modifications. Therefore greater than 20 years experience with the results of the operation are available and the overall improvement has been excellent, with only a small percentage of failures.

Patients who have disabling pain in the knees as the result of arthritic involvement are, as a rule, candidates for replacement of the knee joint. Many measures will generally be tried before the decision is made to perform the knee replacement. The use of exercises, anti-inflammatory medication and injections into the knee may be tried prior to surgery. In the patient who has advanced arthritic changes in the knee, the function of the knee is inadequate and pain will be felt when walking, and many times while at rest. Deformity of the knee will also frequently result and the patient may notice that the knee is becoming bowed or knock-knee deformity is developing. Stiffness and swelling may also be present in the patient with the arthritic knee.

Just as when a tooth is decayed the dentist will remove the decayed area and cap the tooth, so also in the knee the arthritic ends of the knee joint are removed and the ends of these bones are then covered with a metal piece for the femur (thigh bone) and a plastic piece is used with a metal reinforcing tray on the tibia (lower leg bone). Since the knee cap is also commonly involved in the arthritic knee the back portion of it is also covered with a plastic piece. The prosthesis will then be moved by the muscles and ligaments that normally move the knee. The joint will be lubricated by the same synovial fluid that lubricates the normal joint.

It is necessary to prevent the prosthesis from moving as they cover the ends of the bone and therefore bone cement is used to hold the position achieved when the prosthesis is inserted. This material has been used for over 40 years in the body and has proven to be an excellent material in maintaining the fit of the various pieces of the knee replacement. There is currently work being done to promote bone growing into the prosthesis parts, but this is still very experimental and not recommended for the vast majority of patients.

WHAT IS THE USUAL PROCEDURE FOR TOTAL KNEE REPLACEMENT?

After the decision has been made to perform a total knee replacement on a patient the operation time will be scheduled and the patient will be admitted to the hospital the morning of their surgery. Most patients will undergo Pre-Admission Testing prior to admission to the hospital, and this is generally performed a week before admission to the hospital. A very careful analysis is made of blood, urine, electrocardiogram, chest X-ray at the time of the Pre-Admission Testing and this permits a review of all laboratory tests prior to actually being admitted into the hospital. Should any test come back abnormal it can be looked into in plenty of time prior to the patient’s actual admission to the hospital.

A medical evaluation and physical examination is performed by an internist affiliated with the hospital. This will allow a medical doctor to examine you and be sure you are in good condition for the surgery. An anesthesiologist will also see you prior to surgery and explain the options you have with regards to the operation. Many of the total knee replacements we perform are under regional anesthesia with addition of a sedative while the operation is being performed, so the patient is completely unaware of the actual operation. This anesthesia allows the patient to be quickly awake and avoid some of the untoward effects of general anesthesia. The anesthesiologist will discuss this with you and will help you make the best decision for your particular situation.

The operation itself takes about 1½ hours and you will be brought to the Recovery Room after surgery is completed. If the operation is performed late in the afternoon it may be elected to keep you in the Recovery Room overnight.

An automatic bending machine will be applied and immediately begin motion to the replaced knee. This device has many advantageous features, and allows motion to begin almost immediately after surgery. There is generally very little pain associated with the use of the bending apparatus. It will be adjusted by the therapist, nurse or one of the surgical team depending upon your progress. A drain may be inserted into the knee which will be removed the morning after surgery when the dressing is changed. Two days after surgery the dressing on your knee will be removed. An intravenous will be maintained for 48 hours to allow administration of fluids and antibiotics after surgery. Pain medication is now controlled by the patient by pressing a button which then automatically provides pain medication.

Most patients are out of bed on the second post operative day, into a wheelchair and begin to walk, first with a walker, on the second or third post operative day. The therapist will also begin increasing your exercises and bending during this period. As you continue to improve you will be advanced to a cane.

After discharge from the hospital many patients will experience some fatigue their first few days at home. This is common and should not alarm you, but encourage you not to overdo your activity at the outset. It is important, however, to walk and use the knee as much as is comfortable. Also, you must work on the exercises given to you prior to going home. These include strengthening and bending exercises. I will arrange for therapy two or three times a week to ensure that your recovery remains smooth and that your knee is functioning well.

You will return to see me as an out patient six weeks after discharge from the hospital, and you must call my office for this appointment. This is best done either from the hospital prior to discharge or right after you get home. An X-ray of the knee will be taken when you see me for the first visit after surgery.

If you have swelling in the operated leg elevation is very important to reduce this. Most patients will sit a good deal when they first return home and this promotes further swelling in the leg. At all times try to keep the leg elevated preferably on a high stool or surface. If swelling is not responding, additional time should be spent off your feet in a reclining position. If swelling is not responding to these measures call my office. The elastic stockings you are given at the time of discharge should help with this.

If there is any drainage from the incision call my office at once. Put a sterile dressing on the knee incision as soon as this is noted.

Most patients will continue to improve up to six months after total knee replacement. Patients will generally begin giving up the cane at 6 weeks after surgery and knee motion will continue to improve as the scar tissue about the incision becomes more mature and swelling about the knee becomes more reduced. The redness and warmth about the incision will also reduce with time. It is important to use the knee by walking and exercising to maintain knee motion. Athletic activities such as swimming, hiking and golf are excellent for the knee recovering from replacement surgery. Walking, however, remains the best exercise and should be done daily up to one mile or more depending upon the patient’s ability. Running and jumping activities are not good following total knee replacement and should be avoided.

Long term results now looking at patients in whom totals knee replacement was performed 20 years ago continue to demonstrate good to excellent results in the majority of patients. The results are particularly encouraging in view of the improvement in surgical technique and implant design that we are currently using.

As with any major operation complications can occur with total knee replacement. These potential complications fall into three major categories:

A patient after total knee replacement may have a medical complication. This can be of any type and include heart problems, lung problems including a blood clot, or phlebitis in the operated leg. If the patient has a medical history for a particular problem this may be aggravated after surgery. We will review all medical conditions during the Pre-Admission Testing. The internist will examine you before surgery and follow you post operatively should any complication occur. Medical complications are for the most part uncommon but can occur and you must be aware of this possible problem.

The most catastrophic problem that can occur to the knee after replacement surgery is infection. This can occur in the immediate post operative period or be delayed. We operate in special operating rooms to reduce contamination and the risk of infection. We also use space suite type operating suits to prevent interchange of exhaled air between the operating room team and the operated area.

Even so, infection does occur in less than one percent of our patients and should the infection be deep around the prosthesis it is necessary to remove the infected implant and treat the patient with a prolonged course of intravenous antibiotics (6 weeks or more). At that time we are generally able to put the knee back into place. Our results with this technique (re-implantation of the knee after infection) have been very successful to date.

After any implant surgery it is important that you receive antibiotics prior to any procedure which might introduce bacteria into your bloodstream. This includes such procedures as teeth cleaning, extraction’s or extensive gum work, urinary manipulations such as cystoscopy or vaginal or colonic surgery. Any infection that you have come down with should be treated aggressively with antibiotics. If you have any questions regarding this always bring it up with your treating physician or please contact my office.

This refers to problems related to the prosthesis itself and includes such areas as breakage, loosening, and wear. The incidence of failure of the prosthesis in patients with total knee replacement has been extremely low. The most common source of failure when it does occur is loosening of the bond between the prosthesis, bone, and the bone cement. This can result in pain and shift in the position of the replacement and in severe cases may require revision knee replacement.

The incidence of loosening has been extremely low and is in the area of less than five percent in long term follow up. Wear and breakage has been an insignificant problem to date.

The knee cap can be a source of pain in some patients after knee replacement surgery and on occasion further surgery is necessary to better align it or in some cases replace it.

SUMMARY

This pamphlet is designed to give you an overview of what it entails to have your arthritic knee replaced and what you can expect in recovery and long term function of this knee. Results have been very encouraging and the longevity of the prosthesis appears quite good. There is always the chance that a complication can occur and those that I have listed are general ones and do not include an entire list of possibilities. The incidence of these complications is low and we do many things to prevent them but still the patient must be aware that they can occur and may influence recovery.

We have performed many total knee replacements at Pinehurst Surgical and feel it has provided the disabled patient with a painful, arthritic knee with excellent return of function and the ability to return to a more comfortable and productive life.

David J Casey, MD