Total Knee ReplacementA painful knee can severely affect your ability to lead a full, active life. Artificial knee replacement surgery (also called knee arthroplasty or knee replacement) is becoming increasingly common as the population of our country begins to age. When pain, stiffness, knee swelling and limitation of motion in your knee keep you away from your daily activities, you may need a total knee replacement.
Total knee replacement is a major surgery, which usually involves a 3-4 day stay in the hospital and a period of rehabilitation, which takes about 6-8 weeks. A team of health professionals works with the patient to guide his recovery, but the patient is the most important member of the team! We believe that an informed patient is the best ally in achieving success with total knee replacement surgery.
The Goals of Total Knee ReplacementTotal knee replacement is a remarkably successful operation that has transformed the lives of millions of patients by enabling them to be active and pain-free. The goals of total knee replacement are, in order of priority:
- Pain relief.
- Standing and walking that is not limited by the knee.
- Improved knee motion.
- Improved knee strength.
Who would require a total knee replacement operation?Total knee replacements are usually performed on people suffering from severe arthritis. Most patients who have artificial knees are over the age of 55, but the procedure may have to be performed in younger people. Though the circumstances vary, total knee replacement would be considered if:
- You have daily pain.
- Your pain is severe enough to restrict not only work and recreation but also the ordinary activities of daily living.
- You have significant stiffness of your knee.
- You have significant deformity (Knock-knees or bowlegs).
- When conservative methods of treatment like physiotherapy, pain killers etc. fail to provide adequate relief.
What is Total Knee Replacement? What is the total knee joint implant made of?A total knee replacement is a surgical procedure whereby the diseased knee joint is replaced with artificial material. It employs specially designed components, or prostheses, made of high strength, biocompatible, metals and plastics, to replace the cartilage in your knee. The metal that is most commonly used is an alloy of cobalt, chromium and molybdenum. The plastic is ultra-high molecular weight polyethylene.
The Artificial Knee Implants
- The procedure is performed by making a 6-8 inches long skin incision in front of the knee joint followed by separation of the muscles and ligaments around the knee to expose the knee joint.
- In modern total knee replacement surgery, only the worn-out cartilage with minimal bone is removed to replace the diseased cartilage with the artificial joint which is a kind of a surface replacement arthroplasty. The entire knee is not actually replaced.
- Specialized instruments are used to trim off the worn-out surfaces and shape the ends of the bones. As shown in the figure, the femoral component is metallic, and is similar in size and shape to the end of the femur. The tibial component, which goes on the top of the leg bone (or tibia), may have a metallic base, but the top surface is always polyethylene. The undersurface of the knee cap (patella) is also often removed, cut flat and covered with another polyethylene component. The components are attached to the bone with a specialized polymer (polymethylmethacrylate), commonly referred to as "bone cement".
What are the risks and potential complications of total knee replacement?The following is a list of possible risks and potential complications of total knee replacement surgery. These are merely possibilities which we feel patients ought to be aware of, before deciding upon surgery. The most common complications are not directly related to the knee and usually do not affect the result of the operation.
- Anesthesia complications: With modern anaesthetic techniques, they have become a rarity.
- Thrombophlebitis (Blood Clots)
Thrombophlebitis, sometimes called deep venous thrombosis (DVT), can occur after any operation, but is more likely to occur following surgery on the hip, pelvis, or knee. DVT occurs when blood clots develop in the large veins of the leg which may cause the leg to swell and become warm and painful. If the blood clots in the veins break apart, they can travel to the lung where they lodge in the capillaries and cut off the blood supply to a portion of the lung. This is called a pulmonary embolism. The risk of DVT is reduced by early mobilization and giving certain medication after surgery. In a study published in the Indian Journal of Orthopaedics by Dr. A P Mavalankar, it was shown that the risk of developing DVT after lower limb surgery is less than 6 % in Indian population.
The chance of getting an infection following total knee replacement is less than 1 per cent. In order to minimize the potential for infection at the time of surgery, the surgery is performed in an ultra-clean air theatre with laminar air flow. Antibiotics are given just before surgery and continued for 24 hours afterwards. A lot of effort also goes into preoperative assessment and preparation of the patient and treatment of other potential sites of infection like urine, teeth, chest etc .prior to undertaking total knee replacement.
Inspite of taking all the care and precautions, if the prosthetic components become infected, which is not common, additional surgery is sometimes required to treat the infection. It is very important that the infection can be treated without removing the total knee replacement components. In some cases, however, they may need to be removed in order to eradicate the infection. Antibiotics are generally administered for about 6 weeks. Once the infection is treated, new components can generally be implanted. If there is concern that the infection cannot be eliminated, then a knee fusion (arthrodesis) may be recommended. The risk of infection immediately after a knee replacement is very small provided adequate preoperative assessment is carried out; the surgery is performed by an experienced knee surgeon in a clean operation theatre and proper postoperative care is provided.
The risk of infection persists for as long as the total knee replacement is in place. The most common way that a total knee replacement becomes infected is by spread of bacterial infection from another location in the body. Bacterial infections may spread from the mouth because of a dental infection; from a urinary tract infection; as a result of pneumonia or from a skin infection. It is very important that any bacterial infection be treated promptly in order to minimize the chance of spread to the total knee replacement.
In very few cases, the ability to bend the knee does not return to normal after knee replacement surgery.
The major reason that artificial joints eventually fail continues to be a process of loosening where the metal or cement meets the bone. Great advances have been made in extending how long an artificial joint will last, but most will eventually loosen and require a revision. However, you can expect at least 12-15 years of service from an artificial knee, but in some cases the knee may loosen earlier than that. A loose prosthesis is a problem because it usually causes pain. Once the pain becomes unbearable, another operation may be required to revise the knee replacement.