Porzingis crashed to the ground after his dunk with 8:46 left in the second quarter and was taken for an MRI exam that revealed his injury.
"More than a basketball player, he's my brother," Knicks center Enes Kanter said. "I don't want to see anyone going down like that hurting his knee. He's about to be an All-Star. I'm just going to pray for him tonight. He is the most important part of our family."
Eric Bledsoe also had 23 points and Khris Middleton added 20 for the Bucks, who are a season-high seven games over .500
Antetokounmpo didn't appear bothered by a right ankle injury sustained Sunday, particularly when he leaped to catch a lob pass on a fast break and jumped over the 6-foot-6 Hardaway to slam it down .
"I knew (Middleton) was going to throw me the lob," Antetokounmpo said. "It was a bad pass but I was able to get up and go get the ball. I didn't see Tim Hardaway under me. I just went up to get the ball."
Kanter led New York with 19 points and 16 rebounds.
Milwaukee led 50-46 at halftime and opened the second half with six straight points. The Bucks increased their lead to a game-high 21 points on Marshall Plumlee's free throw with 3:43 left in the third quarter.
The Knicks scored the next nine points and pulled within 12 points on a pair of occasions in the final quarter, but never got any closer.
"I thought it was a very good effort," said Joe Prunty, who is 7-1 since replacing the fired Jason Kidd as coach on Jan. 22. "We defended the three again well, rotation good in terms of getting to the spots and running people off the line. I really like the things I saw and we just have to keep doing them every night."
Sean Kilpatrick (16) and Jabari Parker (10) also scored in double figures for the Bucks.
Courtney Lee added 14 points for the Knicks, who have lost four straight, tying their longest skid of the season.
"I think went K.P. went down, it kind of deflated us some," Knicks coach Jeff Hornacek said. "He is a big part of the things we do. No one is going to feel sorry for you when your guys are out, so you have to step it up."
Bucks: Milwaukee guard Matthew Dellavedova sprained his right ankle in Sunday's win at Brooklyn. He underwent an MRI on Monday and subsequent examination by team physician Dr. William Raasch. The exam confirmed a sprained right ankle that is expected to sideline Dellavedova for up to four weeks.
Knicks: New York has dropped 10 of its last 13 against the Bucks. That streak has cost them the lead in the all-time series, as they now trail 106-101. The Knicks have not taken a season series from the Bucks since going 2-1 against them during the 2013-14 season.
Just one of Prunty's seven wins since replacing Kidd has come against a team that was above .500. That was a 107-95 victory over Philadelphia.
Kanter has recorded six consecutive double-doubles. It is the longest streak by any Knick since David Lee had seven straight from Feb. 9-26, 2010.
IN THE MIDDLE OF THINGS
Middleton is the only Milwaukee player to start all 53 games this season. Thon Maker has also played in all 53, but has only started nine times.
The Bucks have had their way with New York City's NBA teams this season. They are 2-0 against both the Knicks and Brooklyn Nets, with all four wins coming within the last 11 days.