Knee joint anatomy

The knee joint is a complex hinge joint connecting the thigh bone (femur) to the shin bone (tibia), with the smaller bone (fibula) alongside it. It contains cartilage that cushions the bones and allows smooth movement. Key ligaments—such as the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL)—stabilize the joint, while the menisci are two crescent-shaped cartilages that absorb shock and enhance stability. The knee is surrounded by a joint capsule that contains synovial fluid, which lubricates the joint, ensuring smooth motion during activities like walking, running, and jumping.