The word ᴱQ. okka “knee” appeared the Qenya Lexicon of the 1910s under the early root ᴱ√OQO “bend” (QL/70). The word appeared again in Early Qenya Word-lists of the 1920s (PE16/137).

Neo-Sindarin: I would retain ᴺQ. occa “knee” for purposes of Neo-Quenya as we have no better alternatives, though what its etymology would be in later conceptions of the language is unclear.