thigh bone 
noun
The femur.Your knee joint is made up of the ends of the thigh bone and shin bone, which normally glide over each other smoothly because they are covered by smooth articular cartilage....
- With Sasha's ACL torn, her thigh bone and shin bone were slipping back and forth, literally wobbling as she walked.
- The ACL is a short band of ropy connective tissue that extends from the back of the thigh bone to the front of the shin bone (tibia).