Knee Injuries: Overview

Knee injuries are injuries that cause temporary or chronic discomfort, pain, or loss of range of motion in the knee or knees.

What Are Knee Injuries?

The knee is the largest joint in the body. It is a hinge joint made up of several bones coming together supported by cartilage * , tendons * , and ligaments * . Fluid in the knee joint provides lubrication to keep the joint working properly. The major bone of the knee is the patella or kneecap. The lower part of the femur * , the upper part of the tibia * , and the patella come together at the knee. The knee moves in two ways: flexion * and extension * . Healthy bones, tendons, and ligaments enable the knee to move in support of walking, running, and all the activities that require effective movement of the knee. Fractures (breaks) or dislocations (displacement or abnormal positioning) of the bone, tears in the tendons or ligaments, or abnormal stretching of the tendons and ligaments can cause damage to the knee and interfere with movement. Problems in moving can include sitting down and getting up, walking and running, or participating in sports.




Arthroscopy is a medical procedure that doctors use primarily to help diagnose joint problems. This procedure, most commonly associated with knee and shoulder problems, allows accurate examination and diagnosis of damaged joint ligaments,





Arthroscopy is a medical procedure that doctors use primarily to help diagnose joint problems. This procedure, most commonly associated with knee and shoulder problems, allows accurate examination and diagnosis of damaged joint ligaments, bone surfaces, and other related joint structures.
Illustration by Electronic Illustrators Group. © 2016 Cengage Learning®.
Athletes and Arthritis

Professional athletes often experience knee injuries that lead to osteoarthritis. They often get arthritis at a younger age than people who do not put as much stress on their knees. Some of those athletes who continued their sport despite having osteoarthritis of the knees are Dorothy Hamill, an Olympic gold medalist in figure skating; Joe Namath, a professional football player; Tiger Woods and Nancy Lopez, professional golfers; actress and dancer Neve Campbell; and Hall of Fame baseball players Nolan Ryan and Hank Aaron.

How Common Are Knee Injuries?

Knee injuries are common and affect people of all ages, especially those involved in high-impact sports. According to the American Academy of Orthopedic Surgeons, there are approximately 11 million doctor visits related to fractures, dislocations, sprains, and ligament tears each year in the United States.

What Are the Causes of Knee Injuries?

Who Is at Risk of Knee Injuries?

While anyone can experience a knee injury, athletes involved in intense physical activity or contact sports are at increased risk.