There are three basic types of arthritis that may affect the knee joint.
Osteoarthritis (OA) is the most common form of knee arthritis. OA is usually a slowly progressive degenerative disease in which the joint cartilage gradually wears away. It most often affects middle-aged and older people.
Rheumatoid arthritis (RA) is an inflammatory type of arthritis that can destroy the joint cartilage. RA can occur at any age. RA generally affects both knees.
Post-traumatic arthritis can develop after an injury to the knee. This type of arthritis is similar to osteoarthritis and may develop years after a fracture, ligament injury, or meniscus tear.
Osgood Schlatters: Osgood-Schlatter disease is an overuse injury that occurs in the knee area of growing adolescents. It is caused by inflammation of the tendon below the kneecap (patellar tendon) where it attaches to the shinbone (tibia). Young adolescents who participate in certain sports, including soccer, gymnastics, basketball, and distance running, are most at risk for this disease. Symptoms include:
- Knee pain
- Tenderness below the kneecap
Meniscal Tear: Meniscal tears are among the most common knee injuries. Athletes, particularly those who play contact sports, are at risk for meniscal tears. However, anyone at any age can tear a meniscus. When people talk about torn cartilage in the knee, they are usually referring to a torn meniscus.
Chondromalacia Patella: Runners, jumpers, and other athletes such as skiers, cyclists, and soccer players put heavy stress on their knees. Runner’s knee is a term used to refer to a number of medical conditions that cause pain around the front of the knee (patellofemoral pain). These conditions include anterior knee pain syndrome, patellofemoral malalignment, and chondromalacia patella.