I would say no.
Every post touches several tables.
I guess it is possible if you are very adept in database tables have days on end to spare and edit the backup file.
But like I said it is several tables
For few at the top of my head
CATEGORIES
FILES
FORUMS
FORUM_LAST_VISIT
FORUM_PERMISSIONS
GROUPS
PERMISSION_LIST
POSTS
TOPICS
USER_DATA
It would be far less work to restore the full backup and do it correctly again.
