ARTHRITIS OF THE KNEE JOINT

Unfortunately, even the most minor of surgical operations carries some risk of complications occurring. Knee replacement surgery is very successful, and complications are relatively uncommon, considering the complexity of the procedure.

The most common complication is blood clots in the legs. The most serious complication is infection. The most important long-term complication is loosening.

1. Bloodclots in the veins of the legs are the most common complication of knee replacement surgery. As long as the clots remain in the legs they are a relatively minor problem. Occasionally, they dislodge and travel through the heart to the lungs (pulmonary embolism). This is a potentially serious problem, since (very rarely) death can result from embolism. The chances of this are one out of several hundred. The internist will prescribe Coumadin (warfarin), heparin or Lovenox (blood thinning drugs) to help prevent clots from forming after your surgery. Additionally, compressive calf pumps are used and leg exercises are encouraged to prevent blood clots. Blood clots can occur despite all these precautions. They are usually not dangerous if appropriately treated, but may delay your discharge from the hospital for two or three days.
   
   
2. Infection. The risk of an infection in first-time knee replacement is currently reported as being about 0.5%. The risk of infection after joint replacement is much greater than with most other operations, unless special precautions are taken. Since bacteria can enter the open wound at the time of the surgery in a regular operating room, we operate in a laminar flow operating room in which special filters provide clean air, free of most bacteria. In addition, the surgeon and assistants wear a sterile space suit. The suit encloses the entire head and body, and includes a sterile face mask. Antibiotics given to you before, during and after the operation further help to lower the rate of infection. Dr. Huddleston uses all these special precautions, and has had only one infected knee replacement in sixteen years as a joint replacement surgeon.
   
   
   The risk of infection in the weeks after the operation is increased if you have rheumatoid arthritis or diabetes, if you have been taking cortisone for prolonged periods of time, if the affected joint has had previous infection, or if you have infection anywhere else in your body" (teeth,bladder, etc) at the time of surgery. The artificial joint can become infected many years after the operation. The bacteria travel through the blood stream from a source elsewhere in the body" , such as from an infected wound, or a gall-bladder infection. Even regular dental work can release bacteria into the blood. Infections of the bladder, teeth, prostate, kidneys, etc. should be cleared up by appropriate treatment well before the day of surgery. Patients who have had joint replacements must take antibiotics by mouth before and after any dental workand must have all infections vigorously treated.
   
   
3. Loosening of the prosthesis from the bone is the most important long-term problem. How long the bond will last depends on a number of factors.
   
   
   1. How well the surgery is done. This is by far the most important factor. Choose a surgeon who has had a great deal of experience with knee replacement, and preferably one who restricts his practice to joint replacement surgery.
   2. The quality of your bones. The harder your bones are, the better the bond will be, and the longer the replacement will last. Osteoporosis is a factor of age, as well as the type of arthritis you have. People with rheumatoid arthritis have especially soft bones.
   3. How active you are. Excessive force on the implant can cause the bond to loosen. If you stayed in bed for the rest of your life the implant will probably never come loose! Activities such as running and heavy lifting should be avoided. The key thing is to use common sense. (See Allowable Activities After Knee Replacement).
   4. Your weight. You should also keep your weight down because every pound you gain adds three pounds to the force to the knee.
   5. The design of the implant. Small abrasion particles from the implant may play a role in implant loosening. Some designs shed more particles than others.
      
      
4. Wound healing can occasionally be a problem after knee replacement. The skin wound over the knee sometimes does not heal completely. Parts of the skin may die after the surgery. This is a major complication which occurs very rarely. Every precaution is taken to prevent it. If it occurs it may require skin grafting and possibly "rotation" of a muscle from the calf to cover the implant and prevent it from becoming infected. Fat legs are more prone to this complication.
   
   
5. Nerve damage can (rarely) occur with knee replacement. The most common nerve damaged is the nerve to the muscles which bring the foot up toward the face (the peroneal nerve). The odds of this occurring are probaby one in many hundreds. If it does occur, the affected nerve usually recovers after 6 to 12 months. Quite commonly the skin around the knee feels "numb" because of small skin nerves that get cut at surgery. Sensation usually returns to normal within a few months.
   
   
6. Patellar complications can occur. Occasionally the knee cap does not track properly causing it to "jump" as the knee bends. The chance of this occurring is less than 1%. The plastic part on the patella can wear through. These problems sometimes need reoperation for correction.
   
   
7. Injuries to the arteries of the leg is a remotely possible but serious complication. The major arteries of the leg lie just behind the knee joint. Arterial injury can usually be repaired by a vascular surgeon. If not, you could even lose your leg. The chance of this occurring is extremely small.
   
   
8. Loss of knee motion: It is difficult to regain bending motion that has been lost for many years and if the knee only bends 90 degrees before the operation, it is unlikely to bend much more after the operation. For unexplained reasons, some patients form excessive scar tissue in the knee after surgery, resulting in diminished bending of the knee (a condition called arthrofibrosis). It is impossible to predict ahead of time which patients might develop arthrofibrosis. Sometimes it helps to manipulate the knee under an anesthetic to break down the excessive scar tissue (see Problems You May Encounter at Home).
   
   
9. Fracture of the knee bones rarely occurs during knee replacement. It is more common during revision knee surgery. Fractures can also occur later from any trauma such as falling down stairs, and (rarely) during manipulation for arthrofibrosis.
   
   
10. Bleeding complications.
    
    • Sometimes bleeding can occur into the wound several days after surgery (“hematoma formation”) as a result of the use of blood thinners. If it is excessive, it may require re-opening the wound under anesthesia to let the blood out.
    • Occasionally the blood thinners may cause bleeding into the urine (or elsewhere), but this is usually temporary, and not of serious consequence.
    
    
    
11. Anesthetic complications can occur, and very rarely even death can occur from the anesthesia. Your anesthesiologist will see you before surgery and explain the risks involved.
    
    
12. Allergy to the metal parts of the implant has occasionally been reported. People who know they have metal allergies should be tested with extracts of the various metal components of the implant prior to surgery. You should notify Dr. Huddleston if you believe you have a metal allergy. Metal allergies are rare and the tests are not completely reliable, so they are only performed if a metal allergy is suspected. Allergy to the plastic parts has never been reported. Small particles of plastic or metal from the implant may cause a reaction in the bone but this is not a true allergy.
    
    
13. Complications From Blood Transfusions. The risks of getting AIDS from screened, banked blood is thought to be in the range of 1 in 250,000 units transfused. The risk of Hepatitis B is estimated to be approximately 1 in 550 units, and Hepatitis C is 1 in 100. It is not known if the risk of disease transmission from directed blood (see Blood Transfusion for Total Joint Replacement) is lower than the risk from ordinary banked blood. The risk of an allergic reaction (hives) is 1 in 500. You can have an allergic reaction to donor blood even though it has been properly cross matched. The risk of a Hemolytic Transfusion Reaction is 1 in 10,000. The risk of a Fatal Hemolytic Transfusion Reaction is 1 in 100,000.
    
    
    All blood intended for transfusion (including your own) is screened by the blood bank for Hepatitis B virus, Hepatitis C virus, syphilis, Human T Cell Leukemia virus, and the AIDS virus.
    
    
14. Fat Embolism. Fat from the bone marrow can get into the circulation and cause lung or neurological symptoms. This is a very rare complication.
    
    
15. Numbness around part of the wound is common and permanent. Never apply hot packs to the area since you could burn the skin.
    
    
16. Other minor complications can rarely occur. You should keep in mind that the chances of any significant complication are very small.

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Special Studies