Yes, genu is a Scrabble word!
...and is worth 5 points in Scrabble, and 8 points in Words with Friends
genu
Noun
1. Hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella
What Scrabble words can I make with the letters in genu?
3 Letter Words
2 Letter Words