Meniscus (plural menisci). A knee joint has two menisci made of a resilient but flexible cartilage. Their curved shapes are often described as crescents, though they are slightly different—the meniscus at the inside of the knee (medial meniscus) is shaped like a C, while the meniscus at the outside of the knee (lateral meniscus) is shaped more like a U. The menisci provide cushion between bottom of the thigh’s femur and the top of the shin’s tibia bone. Each meniscus is thicker at its outer edge. These outer edges help keep the rounded bottom of the femur in place, stabilizing the knee joint.