- Of the many forms of arthritis, most of them are capable of attacking the knee joint and causing such problems as pain, stiffness and a severe lack of mobility. The most frequently seen forms of arthritis that occur in the knee are osteoarthritis and rheumatoid arthritis. In osteoarthritis, the cartilage in the knee erodes, resulting in pain and stiffness. It is normally found in people over the age of 50, but can occur in younger individuals who have suffered knee injuries in the past. Rheumatoid arthritis is a type of the ailment in which the person's own immune system malfunctions and attacks various points in the body. The membrane of joints, such as the knee, is a prime target, with inflammation that can adversely affect bone, cartilage, tendons and ligaments. There are other kinds of arthritis, such as gout, that can also develop in the knee and cause problems.
- Chondromalacia is a term that refers to the softening of cartilage in the kneecap, or patella. This usually afflicts younger adults and is precipitated by muscles being weak, an injury to the knee or overuse of the joint. This condition makes the kneecap rub against the thigh bone's lower end, causing the wearing away of bone in extreme instances. Pain beneath the kneecap that is most noticeable while using stairs is a common symptom of this problem. Physical therapy can often help this condition improve, but sometimes surgery is needed to clean out the injured area of the knee.
- An important part of the knee that acts as a sort of shock absorber is the meniscus. The menisci are composed of tough connective tissues and are shaped like crescent moons, located between the tibia and the femur bones on both the inner and outer sides of the knee. The meniscus can be torn all the way or partially when a person rotates on their knee while standing and bearing weight. A torn meniscus can occur, for example, when a person tries to avoid a tackler in a football game. Meniscus injuries can be severe or minor but usually result in some degree of pain. They can make a knee "give out" and hurt for a while, and then the pain can disappear altogether, only to return weeks or even years later. Rest, therapy and surgery are options to correct this common knee problem.
- The knee joint draws it strength from ligaments that run on the inside, outside and through the center of the joint. When one of these ligaments is damaged, it can be a problem for the knee. Cruciate ligaments can be injured when they are stretched too far or torn, with car accidents and direct impact during sports a common way for this to happen. Cruciate injuries will often make the leg "buckle" when the person attempts to put weight on it, and they can be quite serious. Rigorous exercise programs can fix this problem in many cases, but sometimes complex surgery is required to "rebuild" the damaged ligament.
- The tendons in the knee are vulnerable to conditions such as tendonitis, where they become inflamed from overuse. Runners and cyclists will often experience this knee problem as the tendons in the knee are strained. Sometimes a tendon may rupture or tear in the knee joint. Pain is the most normal symptom of knee tendon problems, especially when they engage in the activity that caused the damage to begin with. Rest and proper exercise can correct minor tendon pain but torn or ruptured tendons will need surgery, followed by a period of recovery and rehabilitation.