'Knees' in the Bible

All hands shall be feeble, and all knees shall be weak as water.

And it shall be, when they say unto thee, Wherefore sighest thou? that thou shalt say, Because of the tidings, for it cometh; and every heart shall melt, and all hands shall be feeble, and every spirit shall faint, and all knees shall be weak as water: behold, it cometh, and it shall be done, saith the Lord Jehovah.

Again he measured a thousand, and caused me to pass through the waters, waters that were to the knees. Again he measured a thousand, and caused me to pass through the waters , waters that were to the loins.