Kristaps Porzingis of the Knicks is helped off the court...

Kristaps Porzingis of the Knicks is helped off the court after an injury in the first half against the Bucks at Madison Square Garden on Tuesday, Feb. 6, 2018. Credit: Jim McIsaac

Kristaps Porzingis brought the Madison Square Garden crowd to its feet with an emphatic dunk over Giannis Antetokounmpo. But Porzingis landed awkwardly and couldn’t get to his feet, silencing those same fans.

Porzingis’ season came to an end on that slam. An MRI revealed that the Knicks’ franchise player tore his left ACL. He left the Garden before halftime of the Knicks’ 103-89 loss to the Bucks and went to an area hospital for further testing. The team announced the results about an hour after the game.

Porzingis will undergo surgery in the near future. A timetable will be provided after that, but the rehab for this major of an injury could keep Porzingis out for the start of next season.

Every case is different, but over the last five years players who suffered torn ACLs were out from nine to 20 months.

It looked serious the moment it happened with 8:50 left in the second quarter. Porzingis stepped on Antetokounmpo’s foot and turned his left ankle on his landing. As he lay on the floor, Porzingis clutched the back of his knee and repeatedly punched the floor.

“He’s my brother, man,” Enes Kanter said. “I don’t want to see anybody just going down like that, holding his knee. That’s a tough feeling.”

Porzingis needed help getting off the court and into the locker room, as he couldn’t put any pressure on it. After Porzingis was assisted off the floor, Knicks president Steve Mills and GM Scott Perry — wearing looks of grave concern — left their seats and made their way to the locker room.

A video surfaced of Porzingis leaving the Garden wearing a long brace to stabilize the knee. He was walking on his own strength. The Knicks were hoping for the best but got awful news.

Willy Hernangomez, Porzingis’ closest friend on the team, said he was “scared” and “worried” and “praying” for Porzingis. Hernangomez had texted and called Porzingis, but hadn’t heard back from the Knicks franchise player.

Porzingis made his first All-Star team this season. He was the Knicks’ leading scorer, averaging 22.9 points and his 2.38 blocks was leading the NBA. The third-year big man ended up playing just 48 games.

Earlier this season, Porzingis appeared to suffer a severe injury when he turned his right ankle in a game against the Heat. He also punched the floor and needed help to get to the locker room that night. Porzingis only missed two games.

But Porzingis has had issues with the left knee this season. He left a game in December against the Nets because of pain in the knee, and missed the next two contests. Two weeks ago, Porzingis sat out against the Warriors because of “left-knee irritation.”

“It’s deflating because he’s a big part of what we’re trying to build around,” Jeff Hornacek said. “A lot of stuff we’re trying to run through him. Other guys are going to have to step up.”

The Knicks (23-32) also lost Tim Hardaway Jr. with 6:23 left in the game after he got kicked in his left shin. It was the same area that kept him out of 20 games with a stress injury. X-rays were negative.

“I’ll be fine,” Hardaway said. “Stinger on the spot where the stress injury was. A direct kick. That hurts. That will bring anybody down.”

Kanter, who led the Knicks with 19 points and 16 rebounds, also was injured. The cut on his mouth opened up again. Kanter said he will undergo oral surgery Wednesday. He already has 18 stitches in his lip. Kanter doesn’t know how much time he will miss, if any.

“They’re just going to try to repair the inside of the mouth,” Kanter said. “They keep putting stitches and then I keep getting elbowed and it keeps opening up. Right now they want to do something so it won’t open up when I get hit.”

The Knicks were leading 31-30 when Porzingis exited. They were outscored 72-59 the rest of the way in the Knicks’ last home game before the trade deadline.

They lost for the fourth straight time and dropped a season-worst nine games below .500. That number could continue to climb with Porzingis out for the year.