The knee joint is a complex hinge joint that connects the thigh bone (femur) to the shin bone (tibia). It allows for bending and straightening of the leg, enabling activities like walking, running, and jumping. The joint is supported by ligaments, tendons, and cartilage, which help stabilize and cushion the bones. The knee joint consists of three main parts: the femur, the tibia, and the patella (kneecap). It is surrounded by a joint capsule filled with synovial fluid, which lubricates the joint and reduces friction. Proper functioning of the knee joint is essential for mobility and overall physical activity.