Anatomy of the KneeThe knee is the largest joint in your body and one of the most easily injured. It is a hinge joint in the leg that connects your larger shinbone (tibia) and your smaller shinbone (fibula connects into the top of the tibia) with your thigh bone (femur). Your knee cap (patella) is a bone embedded within a tendon (sesamoid bone) that rests over a groove at the bottom of the rounded femur and the top of the flat tibia. It protects the bones and soft tissue in your knee joint and slides when your knee moves, giving leverage to your leg muscles. Tendons are tough cords of tissue that connect muscle to bone and help control movement of your joint. The upper leg muscles provide your knees with mobility (extension, flexion and rotation) and strength. The quadriceps muscles straighten your legs (located on the front of your thigh - rectus femoris, vastus lateralis, vastus medialis, vastus intermedius), and the hamstring muscles bend your knees (located on the back of your thigh - semitendinosus, semimembranosus, biceps femoris).  Ligaments are strong, elastic-like tissues that connect bone to bone and provide stability and protection to your knee joint by limiting the forward and backward movement of the shin bone. There are four main ligaments in the knee joint that connect your femur and tibia:
A type of slick, hard, bone-like, flexible connective tissue known as articular cartilage (also called hyaline cartilage) covers the surface ends of the tibia and femur at your knee joint, reducing friction and allowing them to move easily against one another. It is generally 1/8 to 1/4 inch thick. A thick, stringy, egg-like fluid (synovial fluid) found inside the knee capsule, lubricates your knee joint and reduces friction.  In Greek, the word meniscus means "little moon". The menisci are crescent shaped wedges (similar to shock absorbers) located in your knee joint under bumpy knobs at the bottom of your thigh bone (lateral and medial condyles of the femur) and on top of the flat upper surface of your shin bone (tibia plateau). These cover approximately 2/3 of your tibia surface and are thinner on the inside and thicker on the outside. They fill the space between these bones and cushion your femur so it doesn't rub against your tibia or slide off. They are made up of a dense, tougher collagen connective tissue than articular cartilage (fibro-cartilage). When you walk, your weight shifts from one meniscus to the other, and forces on your knee can increase by up to 2 - 4 times your body weight; when you run these increase up to 6 - 8 times your body weight, and are even higher when landing from a jump. The menisci help distribute the weight of your body across your knee joint, lubricate and protect the articular cartilage from damages of wear and tear, stabilize your knee when you slide and turn, and limit extreme knee flexion and extension.There are 2 menisci - lateral meniscus (located on the outside of your knee) and the medial meniscus (located on the inside of your knee). The lateral meniscus is more of an o-shape, and although it is slightly shorter in length, it covers a larger portion of the tibia surface. It is very mobile and is only attached to the tibia on the outside and back of your joint. It does have a muscular connection, where the popliteus tendon goes along the edge and breaks attachment to your joint capsule. It slides forwards and backwards, moving freely in the joint, absorbing up to 80% of the load applied to the outside of your knee. The lateral meniscus is less likely to be injured or torn by force, because it can move and change shape. The medial meniscus is about 3.5cm in length and more of a c-shape, resembling a wedge of an orange. It is tightly attached to the tibia and joint capsule on the back and inside of your knee. It has no direct muscular connection; rather it helps the ACL and MCL stabilize your knee, absorbing up to 50% of the load applied to the inside of the knee. The medial meniscus is quite inflexible and does not move freely in the joint; therefore it is torn more frequently than the lateral meniscus.
| Some Facts About Knees: Approximately 19.4 million visits to physicians' offices in the US per year are due to knee problems. The knee is a complex joint with many components, making it vulnerable to a variety of injuries. Oral medications can mask the pain but do not aid in the healing of knee injuries. Most knee injuries can be successfully treated without surgery. Sadly, regardless of treatment, ACL injuries in high-school youths are associated with a 10-fold increased risk for degenerative knee arthritis later in life. Every year, at least 1 in 3000 Americans between ages 14 and 55 tear an anterior cruciate ligament (ACL).         | |||||
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