Brown, who averaged a career-high 24.7 points on 48.4% shooting this season for Boston, was diagnosed with the injury over the weekend and is expected to have surgery this week.
The Celtics did not provide a timetable for Brown's return, saying that they would provide additional updates when appropriate. Boston is familiar with the procedure, however, as guard Romeo Langford had it Sept. 22. Langford was ready to make his debut in mid-March before he contracted COVID-19 -- about 5½ months after the surgery. A similar timeline for Brown would have him ready to return to the court in late October -- around the expected start of next season, as NBA commissioner Adam Silver has said he hopes the league will be back on its customary calendar.
Brown had missed the past three games with a sprained ankle after a frightening collision with Boston's other young star wing player, Jayson Tatum, in the final minute of a loss to the Portland Trail Blazers on May 2. ESPN front-office insider Bobby Marks reported that Brown, by playing in that game, hit the games-played threshold (58) he needed to qualify for a $446,429 bonus in his contract.
Brown's injury adds to what has been a frustrating season for the Celtics, who sit in seventh place in the Eastern Conference heading into Tuesday's home game against the Miami Heat. If Miami, which won in Boston on Sunday, wins again Tuesday, it would all but guarantee that the Celtics will be part of the NBA's inaugural play-in tournament next week.
Boston has dealt with a variety of injury and COVID-19 issues throughout the season.
Brown will end up missing 14 games with various injuries; he was repeatedly listed on the injury report with nagging issues over the second half of the season. Tatum contracted COVID-19 in January and has openly discussed the challenges he has faced since returning, including the need to use an inhaler. The team's major acquisition at the trade deadline, Evan Fournier, also contracted COVID-19 and has dealt with lingering effects of the virus that he described as being similar to having a concussion. Marcus Smart missed 18 games with a calf injury, costing him all of February. And Kemba Walker's start to the season was delayed by an offseason knee strengthening program -- one that's also seen him sit out the second half of every back-to-back as part of a plan to keep him as healthy as possible.
The result is a team that, after making it to the East finals in three of the past four years, now finds itself in danger of missing the playoffs entirely.