noun
Refers to the front part of the knee, especially the bony prominence. Often used when talking about hitting or injuring the knee.
転んで膝頭をすりむいた。
I fell and scraped my knee.
机の角に膝頭をぶつけた。
I bumped my knee against the corner of the desk.
Compound of 膝 (hiza, 'knee') + 頭 (kashira, 'head'), literally 'knee head', referring to the prominent bony part of the knee.