Twenty-time Grand Slam singles champion Federer pulled out of the Tokyo Olympics last month due to the issue.
Federer, 39, underwent two right knee surgeries in 2020 and has been limited to five tournament appearances this season since his return in March.
When he announced his withdrawal from the Olympics, Federer tweeted: “During the grass-court season, I unfortunately experienced a setback with my knee.”
The Canadian Open, being held this year in Toronto, begins on August 6, while the Cincinnati-based Western & Southern Open starts on August 14 – two weeks prior to the US Open in New York getting under way.
Federer, ranked world No 9, is a two-time winner of the Canadian Open while he is a seven-time champion in Cincinnati.