genu vs hinge joint

genu and hinge joint both are nouns.

Word	Noun	Adjective	Verb	Adverb
genu	Yes	No	No	No
hinge joint	Yes	No	No	No

As nouns, hinge joint is a hypernym of genu; that is, hinge joint is a word with a broader meaning than genu:

genu: hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella
hinge joint: a freely moving joint in which the bones are so articulated as to allow extensive movement in one plane

Other hypernyms of genu include ginglymoid joint, ginglymus.

genu (noun)	hinge joint (noun)
hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella	a joint allowing movement in one plane only
	a freely moving joint in which the bones are so articulated as to allow extensive movement in one plane