The knee is the largest joint in the body and is essential for providing support and stability. According to the book "Joint Structure and Function," the knee's key role in movement makes it highly susceptible to injury and degeneration. However, proper biomechanics and resistance training can prolong the life of the knee and prevent unnecessary wear and tear.
Structure of the Knee
The knee consists of both the tibiofemoral joint, which connects the tibia to the femur, and the patellofemoral joint, which connects the patella and the femur. Sportsinjuryclinic.net notes that the knee is filled with synovial fluid, which provides nourishment to all the surrounding structures associated with the joint. The knee joint is stabilized by a series of ligaments, which serve to maintain position of the joint in a variety of postures. The musculature surrounding the knee consists of the quadriceps and hamstrings.
Function of the Knee
According to "Joint Structure and Function," the primary responsibility of the knee is to support the body during activity. The knee works in harmony with the hip and ankle to support body weight, while allowing shifts in different directions. The knee helps to move and support the body during sitting and squatting movements, and assists with transferring weight. The knee joint can flex, extend and rotate both internally and externally to provide such support.
Knee Joint Injuries
According to Arthroscopy.com, about 6 million people seek medical treatment for knee injuries each year. The knee is highly susceptible to injury because it must support body weight while also providing mobility. This combination can produce a high degree of torque on the joint and serious injury can result. Further, because the femur and tibia are two of the longest levers of the body, the knee is biomechanically exposed to excessive forces. Knee injuries can occur to the menisci, ligaments, bones, muscles and tendons as a result of this force, usually occurring with a sudden rotation of the femur or rotating beyond a normal range of motion.
Degeneration and Disease
The knee is also susceptible to overuse injuries and disease. "Joint Structure and Function" reports that common degenerative conditions in the knee include bursistis, an inflammation of the synovial fluid-filled sacs inside the joint; patellar plica, an inflammation of the patellar synovial capsule; and chondromalacia, an irritation of the cartilage in the knee joint. Any of these conditions can result in noticeable pain and weakening of the joint.
Prevention of Knee Issues
Knee conditions, while common, don't need to become inevitable. "Joint Structure and Function" attests that proper biomechanics and running gait can ensure that the knee is loaded properly while walking or running, and that no excessive twisting of the femur is occurring. Resistance training can help build the muscles surrounding the knee, including the hamstrings and quadriceps, and relieve much of the pressure placed on the joint itself. Finally, avoiding overuse can prolong the life of the knee. The knee is designed to withstand a lot of abuse, but is still susceptible to overuse. Balanced exercise that targets a variety of different movements and muscle groups can ensure that no excessive load is placed on any one area.
References
- "Joint Structure and Function: A comprehensive Analysis"; Pamela K. Levangie and Cynthia C. Norkin; 2000
- The Sports Injury Clinic on the Net: Knee Anatomy
- Arthroscopy.com: The Knee Joint
