The knee is a complicated joint. It moves like a door hinge, allowing a person to bend and straighten their legs so they can sit, squat, jump, and run.
The knee is made up of four components:
- Bones
- Cartilage
- Ligaments
- Tendons
Bones– Three bones meet to form your knee joint: your thighbone (femur), shinbone (tibia), and kneecap (patella).
Cartilage- The ends of the femur and tibia, and the back of the patella are covered with articular cartilage. This slippery substance helps your knee bones glide smoothly across each other as you bend or straighten your leg. Two wedge-shaped pieces of meniscal cartilage act as “shock absorbers” between your femur and tibia. Different from articular cartilage, the meniscus is tough and rubbery to help cushion and stabilize the joint.
Ligaments- There are four ligaments in the knee (two cruciate and two collateral) that act similarly to ropes, holding the bones together and stabilizing them.
- Collateral Ligaments. These are found on the sides of your knee. The medial collateral ligament is on the inside of your knee, and the lateral collateral ligament is on the outside. They control the sideways motion of your knee and brace it against unusual movement.
- Cruciate ligaments. These are found inside your knee joint. They cross each other to form an “X” with the anterior cruciate ligament in front and the posterior cruciate ligament in back. The cruciate ligaments control the back and forth motion of your knee and provide rotatory stability to the knee.
Tendons– Muscles are connected to bones by tendons. The quadriceps tendon connects the muscles in the front of your thigh to your patella. Stretching from your patella to your shinbone is the patellar tendon.
