Kris Medlen and the Braves hoped the ulnar collateral ligament in his pitching elbow was undamaged, but an MRI showed otherwise.

The MRI showed “some involvement in the ligament,” Braves general manager Frank Wren said Tuesday, and the pitcher will have further tests and a second opinion before deciding whether to have surgery.

Medlen had ligament-transplant surgery — aka Tommy John surgery — on the elbow in 2010 and missed most of the 2011 season for a 13-month rehab. He left Sunday’s game against the Mets after grabbing his elbow and hopping off the mound in pain following a fourth-inning pitch.

The injury initially was diagnosed as forearm strain, but the MRI indicated something much worse.

The injury toll is mounting: Braves starter Brandon Beachy lasted two innings of a planned four-inning appearance Monday because of biceps tightness. He’s coming back from two elbow surgeries in a 15-month span. Braves starter Mike Minor also is questionable for the first two weeks of the season after having shoulder soreness in the first week of camp.

The Braves are looking at potential additions to their rotation, including still-unsigned free agent Ervin Santana.

“In this job, there’s a reason why — I know you guys get tired of hearing it, the fans get tired of hearing it — that we say we like our team if we can stay healthy,” Wren said. “It’s sometimes a very fragile position that you sit in when you have a good team. A lot of times you can’t weather a lot of injuries, and when you see a guy like Kris Medlen, who’s been such a good performer for us … when you see him walk off the mound, you get a sick feeling in your stomach. Not unlike when you see Tim Hudson get stepped on at first base (in 2013), on a routine play.

“Things happen. You can’t control them. Nothing you can do about them, it’s just the nature of the business that we’re in. But that (Medlen injury) is a tough one to watch.”

Medlen met with Braves doctors Tuesday to discuss the situation, then left Champion Stadium without speaking to reporters because he needed to get to another medical appointment, a team representative said.

If Medlen has another Tommy John surgery, he would join Braves reliever Jonny Venters in trying to be among the few pitchers to come back from two such surgeries and perform at a high level again in the majors.

Medlen likely was to consult with Dr. James Andrews, who did the 2010 surgery. MRIs on patients who previously had Tommy John surgery can be difficult to read because of scarring in the area of the previous procedure, and the doctor who did the surgery usually is consulted.

“The MRI does show some involvement in the ligament. We don’t know the extent yet,” Wren said. “He’s going to have continued tests. He’s also going to probably have a second opinion. So for us to put a complete diagnosis on it at this time would be premature. We’re going to let this process kind of work its way through over the next few days.”

Wren didn’t specify who the Braves might try to add via trade or free-agent signing, but Monday they contacted Santana, who had a 3.24 ERA and 161 strikeouts in 211 innings the Royals in 2013.

“It’s worrisome, let’s put it that way,” Wren said of the pitching injuries. “We still feel like we have the makings of a very good pitching staff, but you need depth at this level because you just never know what’s going to happen. We’ve seen that over the last two days, how your depth can go to a shortage. We’re evaluating, exploring other opportunities. That’s all we can do at this point.”

With Minor and Floyd expected back in April and May, respectively, and Beachy’s issue not thought to be serious, the Braves might opt to go with a cheaper, temporary fill-in option rather than go over budget to spend $14 million or more for Santana, who reportedly has offers worth about that much from the Orioles and Blue Jays.

“There’s a domino effect of guys that will be ready, but are not going to be ready opening day; they’ll be ready shortly thereafter,” Wren said of Braves pitchers. “So as we go on that premise, that impacts who we go out and look at, how much of a need we think there is in acquiring someone else — we have to factor everything in.”

The potential loss of Medlen could be a blow the Braves have a hard time overcoming. He’s been their best starter since moving from the bullpen in late July 2012, going 24-12 with a 2.47 ERA. His 2.40 ERA since the 2012 All-Star break ranks second among pitchers with at least 250 innings, behind Dodgers ace Clayton Kershaw.

Andrews previously placed the success rate at about 20 percent for pitchers to return to pre-surgery form after a second Tommy John surgery, and the percentage has been higher for relievers than starters.