Harris had an initial surgery on his ankle on Nov. 29 and was expected to be out only between four and eight weeks, but his ankle never healed to a point where he could get back on the floor and feel comfortable.
"Although Joe worked diligently over the past several months to rehab his ankle and exhausted every possible avenue in order to get back on the court with his teammates, it has been determined that he will require an additional arthroscopic surgery in the coming weeks," Nets general manager Sean Marks said in a statement. "While it is expected that Joe will make a full recovery following the procedure, it will unfortunately result in him missing the remainder of the regular season and the playoffs.
"We know how deeply disappointed Joe is to miss this stretch run, but he remains a huge part of who we are as an organization and while he won't be able to contribute on the court, his presence and positivity around the team will continue to be felt by all."
Harris tried to go through different rehab work over the past few weeks to get back on the floor, but Nets coach Steve Nash repeatedly said that he was never able to progress to a point where he was able to join the Nets in formal practices.
"He is just the quintessential teammate," Marks said in an interview with YES Network before the game. "He is what defines a Brooklyn Net ... we feel terrible for Joe and we all know just how much he means to this group."
The Harris news comes on the night star forward Kevin Durant made his return to the floor after missing a month and a half due to a sprained MCL in his left knee. Marks also said during the interview that new swingman Ben Simmons is still out because of a back issue. Simmons' return to the floor remains unclear. He hasn't played since last May after requesting a trade from the Philadelphia 76ers over the summer.
"Unfortunately, his back stiffness has delayed his ability to get on the court with his teammates," Marks said. "So he's been rehabbing this last sort of week to 10 days, and now he'll progress throughout this week with some individual work; hopefully by the end of next week, he's getting more into the team environment. And then we can really ramp up and start him getting into sort of game shape and so forth.
"Although there's no real timetable, we've got to take it day by day and see how he responds. And hopefully sooner the better; we need to get this group together and get minutes together on the court."