膝を曲げて
(膝を屈めるだけの意味なら)to bend one's knees―(礼拝、服従するの意味なら)―bow the knee (to or before god or man)―(屈服するの意味なら)―come to one's knees
to sit knee to knee with one―sit opposite each other
膝にくる
ひざを曲げる
to cross one's legs (tailor-fashion)
to sit knee to knee with one―sit opposite each other
ひざを折る
膝を組むこと
to have a familiar talk with one
ひざをすりむく.