Orioles' Manny Machado undergoes knee surgery
Monday's operation was performed in California by Dr. Neal ElAttrache, according to the team.
The 75-minute procedure included an arthroscopy and open reconstruction of the medial patellar femoral ligament. A hamstring tendon was used to graft a replacement for the ruptured ligament.
Recovery time is estimated to be around six months.
The 21-year-old Machado played in every game this season before the injury, which occurred on Sept. 23 when he stepped awkwardly on first base in a game at Tampa Bay.
A first-time All-Star this season, Machado hit .283 with 14 homers, 71 RBIs and 51 doubles.