Cardinals safety Tyrann Mathieu tore his ACL & LCL ligaments against the Rams on December 8th, surgery was performed on the following Friday December 13th. His recovery could be longer than the normally ACL tear by tearing other ligaments in his knee. Hearing Mathieu hasn't had any sets backs, and sounds like he's ahead of schedule. (9-12 month injury recovery)

NT Alameda Ta'amu tore his ACL in week seventeen last year vs. the Niners on December 29th. He could be activated to 53 man roster after the bye week.  (9-12 month injury recovery)

Most likely both Mathieu & Ta'amu will start training camp on PUP. 

Physically Unable to Perform (PUP) Rules

First, under the NFL Rules, there are two classifications of Physically Unable to Perform (PUP). There's the Active/PUP and the Reserve/PUP. Both PUP classifications are forfootball-related injuries.

The Active/PUP (Preseason PUP list) allows players who are unable to start training camp the ability to sit out until the medical staff provides clearance. Once they are medically cleared, they're allowed to practice immediately.

 via CBA Rules