The Human Knee Joint

The knee, elbow like a certain extent, is a pivotal but not simple. The lower part of the thigh bone grows into the condyles of the femur and tibia than develop in the condyles of the tibia, the junction of these two areas forming the extended knee joint. The small bones on the outside of the knee, known as the fibula, is not involved in the loading, or is actually part of the knee joint, serving only as a connection zone for the muscles that control ankle, foot and toes. The knee functions as a hinge dividing the leg, thereby exercising a high level of muscular force of propulsion, the folding leg flexion and shortening of the leg increased to allow effective approach . 

As approaches full extension of the knee or straightening the major thigh muscles (quadriceps) fully commit themselves to active extension of the knee and the guide in its locked position. Monkeys are unable to straighten their knee while standing, whereas humans can extend their knees completely rule which allows a very low energy use. As the knee approaches full extension of the thigh muscle turns to the inside of the knee to allow it to reach the locking point. Humans can stand on his right knee for long periods with little activity in the quadriceps and hip muscles, combining stability and low effort. 

The cartilage structures called menisci, in the shape of a track bank in a cross configuration and fill some extent between the rounded condyles of the femur and tibia of the surface. Their function has not exactly been proven, but they may help reduce knee lock, minimizing the inappropriate movement of the condyles and the condyles closer to the center of the joint in motion. The third component of the knee joint is the patella, or kneecap, that little bone is lined with cartilage and placed in front of the knee. 

The quadriceps tendon holds the patella or kneecap in it, the main function of muscle is the extension of the knee to lift the body of a chair or negotiate steps. The inner surface of the patella, divided into two facets, is lined with articular cartilage and articulates with the major groove between the condyles of the femur, sliding backwards. The power of the quadriceps extend the knee against the body weight was significantly increased by the presence of the patella. 

When a knee continues to bend and straighten the forward and rear alignment is good and problems are less likely to arise. When a lateral misalignment is added, however, the knee may develop painful conditions. Alignment on the side (knock knee or leg ailments arc type) sets the constraints on one side of the knee by compressing the side of the joint, exposing them to increased wear. Misalignment also changes the angles of the function of the patella and forwarded to the gap, increasing friction of the joint and cause pain. 

During the motion of the knee, the meniscus (knee cartilage) and the patella are subjected to high mechanical strength and cause a number of common knee problems. The range of motion of the knee is usually right (zero degrees) to turn 140 degrees, varying with body size and joint mobility. As the knee goes through the motions of extension and flexion, the condyles large round slip and slide on top of the tibia, with the surface of the tibia in motion too. 

In order to stop the femoral condyles slide back to the tibial plateau they perform internal drag in a direction backward and forward. A bone does not move of its own as the co-evolution of its position, but both move so complicated on the other to allow the desired functional movement is attained. A much wider range of motion is possible with this design. The rotation also occurs at the knee, but is less obvious, more and more apparent that the knee extends closer to the locked position and internal rotation of the femur occurs.