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 Arthritis

Arthritis and Total Knee Joint Replacement
Dr. Ashutosh P Mavalankar

 
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Arthroscopy
Arthroscopy requires only small incisions around the knee which allow the insertion of small instruments, which are about the size of a pen or pencil. With arthroscopy, degenerated and worn cartilage can be trimmed and smoothed, which reduces the source of inflammation. Additionally, the lining of the knee (the synovium), can be trimmed, and this also decreases inflammation. Patients who have knee arthroscopy almost always go home the same day. Recovery from surgery occurs over a couple of weeks. Unfortunately, the benefit of arthroscopy decreases as the degree of arthritis increases. In advanced arthritis, arthroscopy is of little value.

Osteotomy

Some cases, where the leg is imperfectly aligned, can be treated by an osteotomy. An osteotomy is an operation that cuts the bone, either above or below the knee, and re-aligns the knee to a better position. This is a bigger operation than an arthroscopy, and patients usually stay 1 or 2 days in the hospital. It takes 6 to 8 weeks for the bone to heal. Physical therapy is usually required to restore knee motion and strength. Complete recovery takes a number of months. An osteotomy is a good operation, especially for younger patients, and those where the leg is clearly not straight and the cartilage wear is confined to one portion of the knee. Unfortunately, the success of an osteotomy decreases as the degree of arthritis increases.

Uni-compartmental Arthroplasty
In a few cases, only a portion of the knee joint surfaces have worn out and need to the replaced. When only a portion of the knee is replaced, this is called a uni-compartmental arthroplasty. Patients usually stay 2 or 3 days in the hospital and it takes a couple of months for the knee to recover. Physical therapy is usually required to restore knee motion and strength. Unfortunately, in most cases of arthritis, the joint surfaces are diffusely worn. Uni-compartmental arthroplasty is, therefore, less commonly performed than total knee replacement

The Goals of Total Knee Replacement

Total joint replacement is a remarkably successful operation that has transformed the lives of many people by enabling them to be active and pain-free. The goals of total knee replacement are, in order of priority: 
  1. Pain relief
  2. Standing and walking that is not limited by the knee
  3. Improved knee motion
  4. Improved knee strength
Who would require a total joint replacement operation?
Total knee replacements are usually performed on people suffering from severe arthritis. Most patients who have artificial knees are over age 55, but the procedure is performed in younger people. Though the circumstances vary, total knee replacement would be considered if:
  • You have pain daily.
  • Your pain is severe enough to restrict not only work and recreation but also the routine activities of daily living.
  • You have significant stiffness of your knee.
  • You have significant deformity (lock-knees or bowlegs).
  • If your X-rays show destruction of the joint, you and your surgeon will decide if the degree of pain, deterioration and loss of movement is severe enough for you to undergo the operation
  • When conservative methods of treatment fail to provide adequate relief
Total knee replacement and total knee joint implants
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 procedure is performed by separating the muscles and ligaments around the knee to expose the knee joint. In modern total knee replacement surgery, only the worn-out cartilage surfaces of the joint are replaced. 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 below, 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".

Dr. Ashutosh P Mavalankar is Consultant Joint Replacement Surgeon at Apollo Hospitals, Ahmedabad.
 
 
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