From the Dayton Daily News:

News from the medical front also wasn’t so good for the Dragons. First baseman/designated hitter Bobby Mosby (hitting .308) was told he has a probable tear in a left knee ligament that might require surgery.
It’s the type of surgery that can’t be done by arthroscopy, either, meaning he could miss much of the rest of the season. Mosby has an appointment with Dr. Tim Kremchek, Reds’ team physician, Wednesday.

Also Monday, Dr. Kremchek removed two, not just one, bone chips from outfielder B.J. Szymanski’s right knee. Szymanski was supposed to miss 2-4 weeks. It’s now 4-6 weeks.