“It went very well,” Thomson said before referring all other questions about the surgery to Harper.
Thomson said there is no timetable for Harper’s return. Meanwhile, MLB.com is reporting an estimated recovery time of six to eight weeks.
Harper was injured when he was drilled by a fastball on Saturday from San Diego Padres left-hander Blake Snell.
Harper, a two-time National League MVP, is expected to meet with reporters later this week.
The 29-year-old is batting .318 with 15 homers, 48 RBIs and 21 doubles in 64 games this season.
Overall, the six-time All-Star is a career .281 hitter with 282 homers and 800 RBIs in 1,347 games with the Washington Nationals (2012–18) and Phillies.