The timeline for Mixon's return won't be clear under after the procedure is completed, Pelissero and Garafolo reported.
Mixon was in and out of Thursday's game, but managed to total 21 carries for 84 yards on 38 offensive snaps.
Giovani Bernard, who is in his sixth season, has proven himself as a capable backup, but the offense will miss Mixon's big-play capability while he recovers.
The Bengals were 7-2 when Mixon received 15-plus touches during his 2017 rookie campaign. Through two games this season, he had 22 offensive touches in each of the team's games and made the most of the additional work. Mixon averaged 19 carries per game for 89.5 yards and 4.7 yards per carry in the first two games when compared to 12.7 carries for 44.7 yards and 3.5 yards per carry last year.
UPDATE: Mixon underwent successful arthroscopic surgery Saturday and his timeframe for return is roughly between two and four weeks, a source told NFL Network Insider Ian Rapoport.