The knee is often classified as a condylar joint, but it also exhibits characteristics of a hinge joint. This dual classification stems from the unique structure and movement capabilities of the knee.
A hinge joint allows movement primarily in one plane, such as bending and straightening. The knee does have this hinge-like movement, allowing for flexion and extension. However, the knee also consists of two rounded ends of the femur (the femoral condyles) that articulate with the tibia. This anatomical feature gives the knee joint some degree of rotational movement, especially when it is flexed, which is characteristic of condylar joints.
In summary, while the knee primarily functions like a hinge joint during most movements, its complex structure allows it to be categorized as a condylar joint due to the articulation of the femoral condyles with the tibia. This combination enables both flexion/extension as well as additional movement patterns like slight rotation.