Knee Problems

What Do the Knees Do? How Do They Work?

The knee is the joint where the bones of the upper leg meet the bones of the lower leg, allowing hinge-like movement while providing stability and strength to support the weight of the body. Flexibility, strength, and stability are needed for standing and for motions like walking, running, crouching, jumping, and turning.

Several kinds of supporting and moving parts, including bones, cartilage, muscles, ligaments, and tendons, help the knees do their job. (See “Joint Basics”.) Each of these structures is subject to disease and injury. When a knee problem affects your ability to do things, it can have a big impact on your life. Knee problems can interfere with many things, from participation in sports to simply getting up from a chair and walking.

What Causes Knee Problems?

Knee problems can be the result of disease or injury.
Disease

A number of diseases can affect the knee. The most common is arthritis. Although arthritis technically means “joint inflammation,” the term is used loosely to describe many different diseases that can affect the joints. Some of the most common forms of arthritis and their effects on the knees are described a bit later in this booklet.
Injury

Knee injuries can occur as the result of a direct blow or sudden movements that strain the knee beyond its normal range of motion. Sometimes knees are injured slowly over time. Problems with the hips or feet, for example, can cause you to walk awkwardly, which throws off the alignment of the knees and leads to damage. Knee problems can also be the result of a lifetime of normal wear and tear. Much like the treads on a tire, the joint simply wears out over time. This booklet discusses some of the most common knee injuries, but first describes the structure of the knee joint.

What Kinds of Doctors Evaluate and Treat Knee Problems?

After an examination by your primary care doctor, he or she may refer you to a rheumatologist, an orthopaedic surgeon, or both. A rheumatologist specializes in nonsurgical treatment of arthritis and other rheumatic diseases. An orthopaedic surgeon, or orthopaedist, specializes in nonsurgical and surgical treatment of bones, joints, and soft tissues such as ligaments, tendons, and muscles.

You may also be referred to a physiatrist. Specializing in physical medicine and rehabilitation, physiatrists seek to restore optimal function to people with injuries to the muscles, bones, tissues, and nervous system.

Minor injuries or arthritis may be treated by an internist (a doctor trained to diagnose and treat nonsurgical diseases) or your primary care doctor.