Hefner (elbow) will undergo Tommy John surgery Thursday, ESPNNewYork.com reports.

As feared, Hefner will need reconstructive surgery on the elbow, his second such procedure in less than 14 months. The 28-year-old right-hander made 36 starts for the Mets from 2012-13, but he won't pitch at all next season and his future in professional baseball is uncertain.

Hefner (elbow) will likely undergo a second Tommy John surgery, ESPN New York's Adam Rubin reports.

His comeback from the first Tommy John surgery hit a snag during an Aug. 6 rehab game, and after visiting Dr. James Andrews on Sunday, Hefner posted to his Facebook account that a new CT scan and X-rays showed no signs of healing in his elbow. He will rest for a few more weeks to see if his condition improves, but in the likely scenario that it does not, Hefner will tragically have to undergo a second surgery on his elbow, and would likely miss most, if not all, of the 2015 season.

Hefner (elbow) will rest a few more weeks and hope for improvement before deciding whether or not he will undergo his second Tommy John surgery, ESPN New York reports.

Hefner underwent his first Tommy John surgery Aug. 28 of last year and attempted rehab starts in July and August. Unfortunately, a recent MRI revealed a fracture and UCL tear in the same elbow, which will likely require Tommy John surgery. For now, he has elected to rest and hope for some improvement.

Hefner, trying to work his way back from Tommy John surgery, received potentially devastating news Monday, as an MRI showed a fracture and another UCL tear in the elbow, ESPN New York's Adam Rubin reports

Hefner had been working his way back steadily and looked ready to take the next step in his rehab, when he felt pain in his pitching arm last week. If he is able to come back from a second TJS, it won't be until late next season.

Jeremy Hefner (elbow) allowed one run over two innings Thursday in his second rehab appearance with the Gulf Coast League Mets.

Hefner allowed two hits and no walks while striking out one batter. Now 11 months removed from Tommy John surgery, he hopes to rejoin the Mets before the end of the season.

Jeremy Hefner (elbow) will throw off a mound for the fourth time on Sunday.

Hefner resumed throwing earlier this month, but Sunday will be the first time he throws a breaking ball and tries to use his fastball at near full intensity. The 28-year-old had Tommy John surgery last August and hopes to pitch for the Mets before the season is over.

Jeremy Hefner (elbow) is scheduled to throw off a mound on Tuesday.

It will be his first time doing so since last August's Tommy John surgery. Hefner hasn't encountered any setbacks in his recovery from Tommy John surgery and remains hopeful of rejoining the Mets late this season.

Jeremy Hefner (elbow) is hoping to begin throwing from the slope of the mound in 2-3 weeks.

Hefner will expand his flat-ground throwing to 120 feet later this week. He's hoping to make his return from Tommy John surgery late this season."That's my goal," Hefner said. "That's my hope. Hopefully I can come and contribute if there's a need. I think I'd be wasting my time if I wasn't trying to get back to the big leagues."

Jeremy Hefner (elbow) has advanced his flat-ground throwing to 75 feet.

He'll be allowed to throw off a mound once he reaches 150 feet. Making his way back from Tommy John surgery, Hefner could possibly be an option for the Mets late in the season.

Jeremy Hefner (elbow) made 20 throws from 60 feet on Monday in Mets camp and reported feeling fine.

It was Hefner's first game of catch since undergoing Tommy John reconstructive elbow surgery last August. The right-hander might not pitch at all in 2014.

Jeremy Hefner (elbow) announced Sunday that he's been cleared to begin his throwing program.

Hefner is working his way back from Tommy John surgery and will be brought along slowly. The Mets don't expect him to return to game action during the 2014 season.

Mets signed RHP Jeremy Hefner to a one-year contract.

Hefner was non-tendered last week, but the Mets will bring him back aboard for 2014 and help him along in his recovery from Tommy John reconstructive elbow surgery. The right-hander might not pitch all next year.

Mets non-tendered RHP Jeremy Hefner.

Another surprise, as Hefner wasn't even arbitration-eligible this winter, but the Mets apparently aren't willing to pay him $500,000 in 2014 as he recovers from Tommy John surgery. Tough break for the 26-year-old right-hander.

Mets activated RHP Jeremy Hefner from the 60-day disabled list.

It's a procedural move. Hefner had Tommy John elbow surgery in August 2013 and could miss all of 2014.

Mets transferred RHP Jeremy Hefner from the 15-day disabled list to the 60-day disabled list.

It's a procedural move in order to clear room on the 40-man roster. Hefner will be out until at least late next season following Tommy John surgery.

Jeremy Hefner (elbow) wrote on his Twitter account that he will undergo Tommy John surgery on Wednesday morning.

This confirms reports from Monday. Hefner will have a partially torn medial collateral ligament repaired and is unlikely to be a factor for the Mets until late in the 2014 season at the earliest.

Jeremy Hefner will soon undergo Tommy John surgery on his right elbow.

The decision was made after Hefner received a second opinion from Dr. James Andrews. The right-hander will have a partially torn medial collateral ligament repaired during the procedure and can't be counted on for any real production until 2015.

Jeremy Hefner (elbow) will see Dr. James Andrews next Monday for a second opinion.

Tommy John surgery was recommended after Hefner met with doctors in New York this week, but he'll meet with Andrews before making a decision. If he goes ahead with the surgery, he will miss most if not all of the 2014 season.

Jeremy Hefner has been recommended Tommy John surgery.

It's a tough blow for the Mets and for the 27-year-old right-hander, who will likely miss all of the 2014 season if he indeed goes under the knife. Hefner was placed on the disabled list August 14 with a torn UCL.

Jeremy Hefner (elbow) is scheduled to see a doctor Tuesday.

Hefner is dealing with a partially torn medial collateral ligament and the Mets haven't ruled out the possibility of Tommy John surgery. He's going for a second opinion before making a decision.