crookback vs kyphotic

crookback is a noun but kyphotic is not a noun.

Word	Noun	Adjective	Verb	Adverb
crookback	Yes	Yes	No	No
kyphotic	No	Yes	No	No

As adjectives, crookback and kyphotic are synonyms defined as:

crookback and kyphotic: characteristic of or suffering from kyphosis, an abnormality of the vertebral column

Other synonyms of crookback include crookbacked, gibbous, humpbacked, humped, hunchbacked.

crookback (noun)	kyphotic (noun)
a person whose back is hunched because of abnormal curvature of the upper spine

crookback (adjective)	kyphotic (adjective)
characteristic of or suffering from kyphosis, an abnormality of the vertebral column	characteristic of or suffering from kyphosis, an abnormality of the vertebral column