Anthony J. Causi

By:Marc Berman

As Tim Hardaway Jr. undergoes tests to determine the extent of a stress injury to his left shin, a leading orthopedist at Northwestern University told The Post the Knicks shooting guard could be out as little as two weeks or as long as two months.

Dr. Wellington Hsu, professor of orthopedic surgery at Northwestern who wrote a paper on basketball leg fractures, said there are two types of stress injuries — a stress reaction and a stress fracture.

A stress fracture is such “a small break’’ that only an MRI exam or bone scan can determine this type of hairline fracture, Hsu said. If Hardaway has a stress fracture in his shin (the tibia or fibula), he would miss about two months.

A player can still run with a stress fracture but “if you keep playing on it, it will lead to a complete fracture and end your year,’’ Dr. Hsu said.

The hope for Hardaway is either of the shin’s two bones, tibia or fibula, only has a stress reaction.

“It’s no break, just swelling in the bone,’’ Dr. Hsu said.

A stress reaction can lead to a stress fracture if it isn’t rested. However, there are severities of stress reactions.

“There’s piddly ones and really bad stress reactions,’’ Dr. Hsu said. “It could just be a small area of swelling and that’s a different type of animal as someone who has swelling in the entire bone.’’

A major stress reaction would require Hardaway Jr. to rest for 4-to-6 weeks, Dr. Hsu estimated. However, Dr. Hsu said it’s more common for the stress reaction to be minor at which just 1-to-2 weeks of rest is required.

Hardaway Jr., 25, complained of pain in his shin following practice Saturday. He has played through various leg injuries this season — fighting through a left foot ailment that resembles plantar fasciitis coupled with pain in his ankle and calf.

Hardaway Jr. hadn’t missed any of the first 21 games until sitting out Sunday’s loss to Orlando as a last-minute pull following a pregame exam. He didn’t make the trip to Indiana for Monday’s game.

According to Dr. Hsu, Hardaway’s ability to play through the prior ailments could have led to a stress reaction — which is not a break. Surgery is not available for either a stress fracture or reaction.

On Sunday, coach Jeff Hornacek didn’t rule out that Hardaway’s issue could be long-term.