The Athletics announced Friday that Sterner underwent right knee surgery and will miss the remainder of the 2026 season.
Sterner underwent a "chondroplasty of the medial femoral condyle" and also received a PRP injection. The 29-year-old appeared in 46 games out of the Athletics' bullpen this season, logging a 6.12 ERA, 1.38 WHIP and 40:13 K:BB across 42.2 innings. He hasn't pitched since July 17.