YOUR KNEE AND HOW IT WORKS
The knee joint consists of many different components which must work in sync to provide maximum stability and mobility. In this chapter, I describe the different parts of the knee, what they do, and how they work together.
Fascia is a strong, fibrous structure that encases the leg, providing protection and support. A taut layer of fascia can hold fat deposits under the skin in place, helping the knee to maintain a sleek appearance. As we age, however, fascia can lose some of its tone, which result in bulges of fatty tissue that can be mistaken for swelling. Due to the fact that women tend to be thinner than men, the bulging may be more noticeable in women.
There are two groups of muscles that control the knee joint; the quadriceps and the hamstrings. Strong muscles are essential to protect and cushion bones and soft tissue (such as ligaments and tendons) by absorbing the enormous forces that run through the knee.
The quadriceps are a collection of four muscles on the front of the thigh. Along with the quadriceps tendon, the patella (kneecap), and the patellar ligament, the quadriceps are responsible for the extensor mechanism of the leg, that is, the ability to straighten the knee or bring the bent knee to a straight position.
The hamstring muscles, on the back of the thigh, come down from the hip and the pelvis and insert below the knee. They control the knee by allowing it to go from an extended or straight position to a bent position.
The capsule is also a thick, fibrous type structure that wraps around the knee joint. Inside the capsule is soft tissue called synovium. If the knee is injured, the synovium can become inflamed and will secrete excess synovial fluid as a protective mechanism. Inflammatory arthritis, such as rheumatoid arthritis, affects the synovium, which hypertrophies (thickens), secretes fluid, and can potentially destroy the articular cartilage and bone.
There are two major tendons about the knee: the quadriceps tendon and the patellar tendon.
By definition, a tendon connects muscle to bone. However, the patellar tendon connects the patella (kneecap) to the tibia (shinbone), which means that the patellar tendon is really a ligament. Through the years, this ligament has become known colloquially as a tendon, and to prevent confusion, I will call it the patellar tendon throughout this book.
The quadriceps tendon connects the quadriceps muscle to the patella and thus provides power for leg extension.
Overuse of any tendon can result in tendinitis, which may cause local pain and tenderness.
Plicae are embryological remnants of synovial folds—basically a dividing line along the joint in the embryo. As the embryo matures, the dividing lines are no longer needed, and they often rupture spontaneously. However, these long, elastic plicae (similar to rubber bands) remain in about 70 percent of all people. Plicae rarely cause problems; however, in some cases, the bands or folds can get caught between the femur and kneecap and can cause pain.
healthy bones Osteoporosis Rheumatic