YOU SAID:
My kneecaps are hard and circular
INTO JAPANESE
私の膝蓋骨は硬くて円形です
BACK INTO ENGLISH
my patella is hard and round
INTO JAPANESE
私の膝蓋骨は硬くて丸いです
BACK INTO ENGLISH
my patella is hard and round
That didn't even make that much sense in English.