If we needed to recall someone, they'd put someone on LTIR, such as Greene. They can put him on retroactively so that he could come off for the homestand.
LTIR a player must miss at least 24 days and 10 games. So no it's not quite that easy. If your wondering that is on page 290 of the CBA.
(d)
Bona-Fide Long-Term Injury/Illness Exception to the Upper Limit
.
In the
event that a Player on a Club becomes unfit to play (i.e., is injured, ill or disabled and unable to
perform his duties as a hockey Player) such that the Club's physician believes, in his or her
opinion, that the Player, owing to either an injury or an illness, will be unfit to play for at least (i)
twenty-four (24) calendar days and (ii) ten (10) NHL Regular Season games, and such Club
desires to replace such Player, the Club may add an additional Player or Players to its Active
Roster, and the replacement Player Salary and Bonuses of such additional Player(s) may increase
the Club's Averaged Club Salary to an amount up to and exceeding the Upper Limit, solely as,
and to the extent and for the duration, set forth below. If, however, the League wishes to
challenge the determination of a Club physician that a Player is unfit to play for purposes of the
Bona-Fide Long-Term Injury/Illness Exception, the League and the NHLPA shall promptly
confer and jointly select a neutral physician, who shall review the Club physician's determination
regarding the Player's fitness to play.