Royals' pitcher Matt Strahm undergoes season-ending knee surgery

Royals pitcher Matt Strahm will miss the rest of the season after undergoing a surgical procedure Friday to repair a torn patellar tendon in his left knee.

Royals manager Ned Yost said Strahm, 25, is expected to miss close to four months of baseball activities. He should be healthy at the start of spring training in 2018.

“He’ll be ready for spring training,” Yost said. “He’ll be good to go.”

The surgery appeared a likely scenario after the Royals placed Strahm on the 60-day disabled list and set up an appointment with a specialist. The surgery was performed by Dr. Timothy Kremchek, a surgeon at Beacon Orthopaedics & Sports Medicine in Cincinnati. Strahm received a second opinion Thursday after sustaining the torn patellar tendon last weekend during a series against the Minnesota Twins.

Strahm’s surgery came as the Royals received distressing news on starting pitcher Nathan Karns, who has been on the disabled list since the middle of May after experiencing soreness in his forearm.

Yost revealed Friday that Karns has been battling symptoms of thoracic outlet syndrome, a neurogenic condition caused by the compression of nerves near the neck and shoulder. Karns could be headed for season-ending surgery to address the issue, Yost said.

The injury could threaten the depth of a starting rotation as the calendar presses on toward the middle of July.

One thing is clear: The injury to Strahm will leave a hole in the middle of the Royals’ bullpen. One year after a dynamic debut in the second half, Strahm has posted a 4.30 ERA and 26 strikeouts in 23 innings of relief work.

His numbers appear demonstrably better after some struggles during the first week of the season. He has allowed just four earned runs in relief appearances since returning from a brief demotion to Class AAA Omaha in early April. He posted a 2.08 ERA in May before joining the rotation on June 15.

“He was a nice arm to have back there,” Yost said.

For now, the Royals have an extra lefty in the bullpen as they begin a three-game series against the Los Angeles Dodgers. After a day off on Thursday, left-hander Travis Wood was skipped in the rotation.