Jeff Seidel of MLB.com reported that the 30-year-old righty underwent an MRI that showed no new damage, but he still needs time to recover.
"I was pumped to hear [this news]," he said after Thursday's game. "I thought something else was going on just by the way it felt and even from the pain I felt [Wednesday] -- and the improvement into today was significant. It's making strides."
Hammel left Tuesday's game against the Tampa Bay Rays in the fourth inning after feeling pain in that knee.
It has been a matter of concern for him. An arthroscopy was performed on it in July, and now it hits a so-called "hot spot", which means the pitcher will now work on strengthening it for a few days.
Hammel is 8-6 with a 3.43 ERA for Baltimore.