Hello! Dr. H again, it’s Sunday afternoon. Why does having knee replacement relieve pain from arthritis when the procedure itself sounds so bad? That is the question that a patient asked me last week. So let us first discuss what arthritis is and why is it painful.
The knee joint is a complex joint where the thigh, shin and knee cap meet. This is all held together by an array of muscle, tendons, ligaments, and meniscal cartilage. Where the bones actually meet they are covered with specialized cartilage called hyaline cartilage. This cartilage is very durable and strong. Its most important characteristic is a super slippery surface. The hyaline cartilage can last a lifetime in most people; however, because of genetics, injury or other reasons it can wear out. When the hyaline cartilage is injured or worn out, then arthritis begins to form.
When the raw ends of the bone are exposed to each other this leads to all the symptoms of arthritis. Imagine that ball bearings that were once smoothed and well-oiled become roughened. Once the bone is rubbing together this causes grinding, swelling with pain (inflammation), difficulty in moving, giving way and bone pain. We can treat the inflammatory symptoms of arthritis with icing, anti-inflammatory medications, either oral or injections. Sometimes arthroscopy can “clean out” the degraded tissue for temporary relief. Braces can help, a little if the knee becomes deformed. But no matter what we try, the hyaline cartilage cannot be re-grown in the knee.
Any person who has severe arthritis can tell you, that the pain is severe. When the pain reaches that level, then a knee replacement is needed. During the replacement procedure I remove just the surface of the knee, straighten the knee, restore motion and insert a knee made of metal and plastic. This reestablishes the smooth nearly frictionless motion to the knee. When the new properly functioning knee is in place the symptoms of the arthritis are eliminated.