There are two different types of arthritis that affect the knees. One type is caused by the wear and tear we put on our knee joints and the other type is caused by inflammation. Before we discuss the types of knee arthritis, it is important to understand the makeup of the knee.
The knee consists of three bones, the tibia (shin), the patella (the kneecap), and the femur (the thigh). These three bones form two separate joints. The tibiofemoral joint is the knee joint and the patellofemoral joint is the kneecap joint. The ends of all the knee bones are covered with thick layers of cartilage.
Cartilage is found throughout the body. It is spongy and thick material that lines all the joints, providing cushioning and lubrication. Cartilage also works as a shock absorber, taking the force impacts going through the knee and spreads them evenly through the knee joint.
As a person ages, cartilage erodes and wears away. When this happens, the person can develop bone spurs in the areas where the cartilage is no longer think or spongy enough to protect the bones and joints. This means there is bone to bone contact, which results in serious stiffness, pain, and inflammation.
What are the different types of knee arthritis?
As mentioned above, there are two different types of knee arthritis, osteoarthritis and rheumatoid arthritis.
Osteoarthritis: This type of arthritis is a result of degeneration of the cartilage and bones. It is often referred to as wear and tear arthritis. According to the Centers for Disease Control and Prevention (CDC), there are more than 32 million people who suffer from osteoarthritis. It is the most common type of arthritis in people who are 65 or older.
When cartilage is healthy, it creates a large space between the bones (femur and tibia), with plenty of lubricating fluid. The surfaces of the bones are smooth, and when the person bends their knee, the joint moves easily with no pain. This is because of the cartilage.
But if the cartilage begins to thin out, the bones under the cartilage start to thicken, creating new bone as it tries to protect itself. This new bone is referred to as bone spurs. The spurs create a jagged, uneven surface on the joint surface. All these changes leave less space between the bones, causing the bones to rub against each other, creating pain. The bone spurs also cause limited movement, resulting in stiffness.
Rheumatoid arthritis: This type of arthritis is actually a chronic inflammatory disorder that can affect the whole body. The joints also develop excess fluid. The inflammation and fluid begin to break down the cartilage, causing the knee joints. Rheumatoid arthritis is much less common than osteoarthritis, but it does affect people who are younger.
The onset of rheumatoid arthritis usually hits when a person is in their forties, and it may be time for them to seek a consultation with an arthritis doctor in Pottstown, PA. In addition to the knees, this type of arthritis often affects other joints, especially the hands, feet, and neck. Instead of constant pain, patients usually suffer flare-ups of the condition, where symptoms just come and go. When a patient is suffering a flare-up, it is usually worse when they wake up in the morning, but eases up as they move around.
Thanks to Premier Osteoarthritis Center of Pennsylvania for their insight into knee pain and arthritis treatment.