femur

the thigh bone, which is the long BONE extending from the hip to the knee and is the strongest bone in the body. It is the weight-bearing bone of the body and fractures are common in old people who have lost bone mass. It articulates with the PELVIC GIRDLE at the upper end, forming the hip joint, and at the lower end with the PATELLA (knee cap) and TIBIA to form the knee joint.