膝蓋骨

Noun

 * 1) patella; kneecap
 * 2)  knee joint

Etymology
Compound of. First cited to a medical terminology list from 1872.

Noun

 * 1)  a kneecap, a patella

Usage notes
Both and  are also in use in modern Japanese, with  used more frequently of the two. The term is somewhat more technical, a bit like English  compared to.