ankle joint vs ankle

ankle joint and ankle both are nouns.

Word	Noun	Adjective	Verb	Adverb
ankle joint	Yes	No	No	No
ankle	Yes	No	No	No

As nouns, ankle joint and ankle are synonyms defined as:

ankle joint and ankle: a gliding joint between the distal ends of the tibia and fibula and the proximal end of the talus

Other synonyms of ankle joint include articulatio talocruralis, mortise joint.

ankle joint (noun)	ankle (noun)
a gliding joint between the distal ends of the tibia and fibula and the proximal end of the talus	a gliding joint between the distal ends of the tibia and fibula and the proximal end of the talus