Patella

The patella is the kneecap bone, right at the bottom of your femur.

(from: wikipedia - patella)

It is the small bone right at the point of your knee.

Femur

The hip bone or pelvis connects to the thigh bone of your leg,
which is called the femur.

The femur is the longest, heaviest and strongest bone in the human body.

(from: wikipedia - femur)