The Arthritic Knee
There are many types of arthritis of the knee, but osteoarthritis (Degenerative Joint Disease) is by far the most common. In some patients, the cartilage in the knee simply deteriorates as a direct result of aging. With age, there is a loss of water content and breakdown of proteoglycans—the complex glycoprotein that provides the structural element of cartilage. With the loss of water content and breakdown of proteoglycans, cartilage throughout the body begins to crack, flake, float within the joint, cause inflammation, and leave exposed bone (Figure 1).
Eventually, the bone becomes the bearing surface resulting in pain, stiffness, cracking and popping sensations, poor alignment, and worsening symptoms (Figure 2).
Many patients develop arthritis as a direct result of injury. Most commonly, a twisting injury to the knees causes a loss of cartilage and/or a ligament injury. Over a long period of time, especially when left untreated, there is progression to further cartilage loss and deterioration of the joint.