There are three main types of arthritis:

• Inflammatory Arthritis,
• Osteoarthritis and
• Post-Traumatic Arthritis.

Any condition that damages the cartilage covering the bony surfaces of the knee joint, (the end of the femur, the top of the tibia or the back of the patella), will cause damage and breakdown of the cartilage. This is Arthritis when the cartilage cannot provide the normal smooth motion and withstand the forces placed upon it with day-to-day activities and sports. This leads to pain and disability.

Inflammatory arthritis is a condition that usually affects multiple joints. There are several types including Rheumatoid Arthritis and Psoriatic Arthritis. The inflammation created within the joint also affects the soft tissues and can cause swelling, instability and stiffness as well as chronic pain.

Osteoarthritis or OA, is a degenerative (wear and tear) condition affecting the smooth cartilage that covers the surface of a joint. Unlike inflammatory arthritis, osteoarthritis usually affects one joint, or rarely two at a time. It can affect the knee joint. OA usually comes on in older patients as the cartilage wears out over time, our joints aren’t really designed to last as long as we are now expecting them to. Sometimes osteoarthritis can occur early in patients with abnormal mechanics of the knee, instability or following trauma. Other factors can include obesity, avascular necrosis (loss of the blood supply to the bones), or may be the long term result of a childhood knee condition. Anything that damages the cartilage can predispose it to osteoarthritis.

Post-Traumatic Arthritis occurs following injury to the joint, namely trauma. A fracture through the joint surface causes direct damage to the cartilage which will then degrade, but can also cause irregularities to the joint surface, such as steps or gaps. When this occurs, the forces at the irregular point become very high, and overcome the ability of the cartilage to withstand them. The cartilage then begins to degrade or break down causing arthritis. This can occur very quickly following an injury.