The knee joint allows the lower leg to move while the upper leg stays in place supporting the weight of the body.
The knee, also known as the tibiofemoral joint, is a synovial hinge joint that connects the thigh bone (femur) to the shin bone (tibia). The other bones that make up the knee joint are the fibula (smaller bone that runs alongside the tibia) and the patella (aka the kneecap).
How it works:
There are tendons connecting the knee bones to the leg muscles that move the knee joints. The ligaments join the knee bones and provide stability to the knee. The medial collateral ligament (MCL) prevents the knee from sliding toward the middle. The lateral collateral ligament (LCL) prevents the knee from sliding to either side. The anterior cruciate ligament (ACL) plays an important role in preventing hyperextension of the knee by limiting forward movement of the tibia. The posterior cruciate ligament (PCL) sits behind the ACL and prevents the tibia from moving too far backward.
To protect the knee and provide cushioning and lubrication from friction and outside sources, there are small pockets of fluid (bursae) and fat pads (articular fat pads) that absorb shock and provide cushioning to other ligaments as the knee moves
Since the purpose of the knee joint is to permit tension and flexion of the lower leg, the range of motion is limited by the structure and anatomy of the bones and ligaments. The knee generally allows for a range of 120 degrees flexion.
The knee is a very complex joint and plays an important role in every day activities. It’s important to take proper care of your joints as well as avoid overuse and/or injury from exercise and other activities.