Derek Holland's knee injury resulted in him undergoing microfracture surgery earlier this week, the Ranger said today, according to Gerry Fraley.
Though it has been known that Holland underwent surgery and there was no ligament damage, it wasn't known until now that Holland had microfracture surgery.
The Rangers reportedly expect him to be out until the All Star Break. Fraley mentions in his blog post that Scott Feldman underwent microfracture surgery in November, 2010, and didn't return to the majors until July 22, 2011. That, however, was the first time Feldman pitched in the majors after the surgery...he was activated before then, after rejecting the Rangers' efforts to outright him to the minors, and he was capable of pitching in the majors well before then, with the Rangers leaving him on a rehab assignment because there was no opening on the major league pitching staff.