Thuney, a first-time All Pro this season, injured a pectoral muscle at the end of the Chiefs' divisional round win over the Buffalo Bills in mid-January. He missed Kansas City's AFC championship game against the Baltimore Ravens the ensuing week.
Thuney finished the regular season with a 99 pass-block win rate, which was the best in the NFL this season. The Chiefs are going up against a 49ers defense with two edge rushers in the top 20 of pass-rush win rate (Chase Young and Nick Bosa) and two defensive tackles in the top 10 (Javon Hargrave and Arik Armstead).
Nick Allegretti, who has started 17 games over five seasons for Kansas City, will replace Thuney at left guard. He has started in 13 regular-season games and four more in the postseason, including the AFC championship and when the Chiefs lost to the Tampa Bay Buccaneers in Super Bowl LV.
And while McKinnon was activated from injured reserve, ESPN reported that he's a game-time decision to play against the 49ers. A groin injury has kept McKinnon out of the lineup since Week 15 against the New England Patriots.
He was primarily used as a third-down, pass-catching back for Kansas City this season. He hauled in 25 receptions for 192 yards and four touchdowns, and added another score and 60 yards on the ground in 12 games.