The knee is a rather complex joint that allows the leg to be folded and extended during walking, as well as some rotational movements.
The bones of the knee
The knee joint is made up of the lower end of the femur (thighbone), the upper end of the tibia (shinbone) and the patella (kneecap) held by the quadriceps.
The bone extremities are covered with cartilage, which allow a harmonious sliding of the articular surfaces.
Meniscus
The knee has two meniscuses (medial and lateral) that interpose between the femur and the tibia and act as shock absorbers during walking, running or jumping.
Ligaments
Four ligaments hold the knee. Two collateral ligaments : medial (on the inside of the leg) and lateral (on the outside), and two cruciate ligaments : anterior (ACL) and posterior.