The club has not announced a timeline for Sogard's recovery, but the infielder said last week he expected to miss at least six weeks.
Sogard began the season on the disabled list because of a neck strain. It wasn't until he began a rehab assignment with Class A Advanced Stockton that he experienced lingering knee discomfort he said dates back to last year.
• Right-hander Henderson Alvarez completed three innings in his first Minor League rehab start on Wednesday, allowing one run on three hits with one strikeout for Class A Advanced Stockton. Alvarez, expected to join the A's rotation in May, threw an additional 15 pitches in the bullpen following his departure to reach 45.