Your knee joint is made up of bone, cartilage, ligaments and fluid. Muscles and tendons help the knee joint move. When any of these structures is hurt or diseased, you have knee problems. Knee problems can cause pain and difficulty walking. Arthritis is the most common disease that affects bones in your knees. The cartilage in the knee gradually wears away, causing pain and swelling. Injuries to ligaments and tendons also cause knee problems. A common injury is to the anterior cruciate ligament (ACL). You usually injure your ACL by a sudden twisting motion. ACL and other knee injuries are common sports injuries.

Treatment of knee problems depends on the cause. In some cases your doctor may recommend knee replacement.

Common Knee Injuries

Many athletes experience injuries to their knee ligaments. Of the four major ligaments found in the knee, the anterior cruciate ligament (ACL) and the medial collateral ligament (MCL) are often injured in sports. The posterior cruciate ligament (PCL) may also be injured.

ACL injury

Changing direction rapidly, slowing down when running, and landing from a jump may cause tears in the ACL. Athletes who participate in skiing and basketball, and athletes who wear cleats, such as football players, are susceptible to ACL injuries.

MCL injury

Injuries to the MCL are usually caused by a direct blow to the outside of the knee. These types of injuries often occur in contact sports, such as football or soccer.

PCL injury

The PCL is often injured when an athlete receives a blow to the front of the knee or makes a simple misstep on the playing field.

Torn cartilage

When people talk about torn knee cartilage, they are usually referring to a torn meniscus. The mensicus is a tough, rubbery cartilage that is attached to the knee's ligaments. The meniscus acts like a shock absorber. In athletic activities, tears in the meniscus can occur when twisting, cutting, pivoting, decelerating, or being tackled. Direct contact is often involved.

Treatment of Knee Injuries

Orthopaedic surgeons use a variety of methods to treat knee injuries in athletes. A common method used to treat mild knee injuries is R.I.C.E., which stands for rest, ice, compression, and elevation. Rest the knee by staying off it or walking only with crutches. Apply ice to control swelling. Use a compressive elastic bandage applied snugly, but loosely enough so that it does not cause pain. Finally, keep the knee elevated.

The most important advice is to seek treatment as soon as possible, especially if you:

1) Hear a popping noise and feel your knee give out at the time of injury
2) Have severe pain
3) Cannot move the knee
4) Begin limping
5) Have swelling at the injury site

Adopted from nih.gov