The most common problems of the knee are the result of either a disease or a specific type of injury. There are various diseases and types of injuries that can affect the knee. We only provide a summary of the most common types of diseases and injuries of the knee. More comprehensive information can be retrieved from reliable sources listed under the Research section.
Different types of arthritis could affect the knee of which the most common known include:
Osteoarthritis – cartilage wears away gradually which causes changes in the adjacent bone. Joint injury or being overweight could be causes of Osteoarthritis. It is also associated with aging.
Rheumatoid arthritis – this is an autoimmune disease generally known to affect younger people. The immune system primarily attacks the membrane (synovium) that lines the joint. This then causes inflammation of the joint which causes the cartilage and bone to be completely damaged. In some instances the muscles, tendons and ligaments are also harmed.
Other rheumatic diseases include gout, systemic lupus erythematosus (lupus), psoriatic arthritis and reactive arthritis.
- Gout is an acute and painful form of arthritis and occurs as the bodily waste product, uric acid, forms crystal residue in the joints.
- Systemic lupus erythematosus (lupus) is an autoimmune disease known for the destructive inflammation of the knee joint.
- Psoriatic arthritis refers to inflamed joints that present symptoms of arthritis for patients already inflicted with psoriasis or even in the emerging phase of psoriasis.
- Reactive arthritis describes forms of arthritis as the result of infectious agents like bacteria or viruses.
Chondromalacia is the softening of the articular cartilage of the kneecap and mostly occurs in young adults. It could be the result of an injury, overuse, the misalignment of the patella or muscle weakness. Instead of the kneecap gliding smoothly over the lower end of the thigh bone, it rubs against it and roughens the cartilage underneath the kneecap. The damage may range from a slightly abnormal surface of the cartilage to a surface worn away to the bone.
The menisci can be easily injured through the force of rotating the knee while bearing weight. A partial or total tear may occur when a person quickly twists or rotates the upper leg while the foot stays still (for example turning to hit a tennis ball). A tiny tear cause the meniscus to stay connected to the front and back of the knee. However, a large tear could cause the meniscus to be hanging by a thread of cartilage. The seriousness of a tear depends on its location and extent.
Cruciate ligament injuries
Cruciate ligament injuries are also referred to as sprains. Although it is not always associated with pain, it causes immobility. Generally, a sudden twisting motion causes theto stretch or torn (or both). This could happen when the feet are planted one way and the knees are turned another. On the contrary, direct impact like a rugby tackle causes injury to the posterior cruciate ligament.
Medial and lateral-collateral ligament injuries
The medial collateral ligament is more easily injured than the lateral-collateral ligament. The cause of collateral ligament injuries is typically from a blow to the outer side of the knee that stretches and tears the ligament on the inner side of the knee. Such blows occur in contact sports such as rugby or hockey.
Knee tendon injuries ranges from tendinitis (inflammation of a tendon) to a ruptured (torn) tendon. If a person overuses a tendon during certain activities such as cycling or running, the tendon stretches and becomes inflamed. After repeated stress, the tendon may tear.