d'Arnaud suffered the injury on June 25 while attempting to break up a double play at second base. He was originally expected to be out at least six to eight weeks and with the season in Triple-A Las Vegas coming to an end on Sept. 3, there doesn't appear to be enough time for a return.
"At the outset of the injury, it was expected that this was a six to eight, possibly 10-week, recovery," Blue Jays manager John Farrell said. "To look forward on how he responds when he gets into that later part of the rehab process will determine whether he gets back on the field."
d'Arnaud initially was projected as a possible callup in September when rosters can be expanded to 40 players. He is now expected to head to the Arizona Fall League at the end of the year as a way to make up for the lost at-bats.
The California native is ranked the Blue Jays' No. 1 prospect according to MLB.com. He was hitting .333 with 16 home runs and 52 RBIs in 67 games with Las Vegas prior to the setback.
Knee injuries can often be devastating for catchers to overcome, but the Blue Jays remain optimistic this one isn't severe. Both the anterior cruciate ligament (ACL) and medial collateral ligament (MCL) avoided any damage, while the PCL can be healed without surgery.
"Every indication was because the MCL and the ACL were sound, there was no meniscus damage, it's a little less of a concern," Farrell said. "But any time you're talking about the position, sure, a knee injury is of some concern.
"It's an injury that will heal on its own."