Your knee joint consists of three bones:
- the femur (thigh bone)
- the tibia (shin bone)
- the patella (kneecap)
The primary movement of your knee joint is:
- flexion (bent)
- extension (straight)
The joint also has a small amount of rotation when your knee is in flexion (bent). But if your knee is in extension (straight), rotation can only occur at your hip.
Optimal performance of the knee depends on the structures above and below it. If the pelvis and hips and foot and ankle are not moving well, the knee will suffer, guaranteed.
The knee needs good balance between inner thigh and outer hip strength. The quadriceps help the knee extend (straighten). The hamstrings help the knee flex (bend). But strong core, hip abductors, and glutes are also imperative for healthy knees.