– Such a missed opportunity. If circumstances had been different, if the Twins catcher had chosen an alternative and more risky procedure, players who injured their knees for the next several decades could have opted to undergo Jason Castro surgery.

But Tommy John is safe for now. And Castro is healthy, which is all that matters.

“It turned out really well, fortunately,” said the 31-year-old Californian, who missed most of the 2018 after having surgery on his right knee last May. “It’s been a process to get used to squatting on it again, bending at full range, but it feels really good now.”

Of course, “now” was not really the only consideration when Castro felt that familiar nagging pain in his knee last April. He has had that same knee operated on four times during his career, a pattern that’s worrisome but manageable. The diagnosis was the same as the three previous times: a tear in the meniscus, which is the cartilage wedged between the bones of the knee that serves as a cushion.

“This is not uncharted territory for me, but you kind of have to hold your breath and hope that there is enough of the meniscus left that it can be repaired. After four operations on the same meniscus, you don’t know for sure,” said Castro, who took no chances: He had the procedure done at the nationally known Steadman Clinic in Vail., Colo. “If it can’t be repaired, then you just remove it. But that’s not exactly a great solution for an athlete.”

That’s because removing the meniscus means the knee is largely bone-on-bone, which humans can tolerate for a while. But a catcher? It was a daunting possibility.

“In the short term, removal would actually be better, because you don’t have to wait for the tear to heal. I could have been back within a couple of months last year,” Castro said. “But I probably would have guaranteed myself arthritis by the time I was 40. So the tradeoff is pretty massive.”

There was a third possibility, but one that his doctors didn’t recommend. Like Tommy John surgery to stretch a new ligament into an elbow, doctors have begun transplanting new meniscus into knee joints. The procedure is unproven and “the success rate is about 50-50 for athletes,” mostly moguls skiers, Castro found. “Some of the transplants have failed just from walking around,” he said. The notion of being a pioneer, of being the first baseball catcher to repair his knee with a transplant, of turning the procedure into Jason Castro surgery didn’t appeal to him?

“Nah, I’ll leave that to someone else,” he said. “I might need to consider it down the road, though, just because of my history and continuing to catch on it. It’ll probably be in my future at some point, maybe when it’s more proven.”

Besides, the repair he underwent was complicated enough. Once he was under, doctors used a large-gauge needle to draw bone marrow from his hip, in order to inject it into the knee. Then they drew blood, spun it in a centrifuge until it formed a fibrin clot, and sewed the clot into the meniscus, with the blood serving to promote healing.

All that was followed by seven months of daily rehabilitation exercises — all so he could go back and resume the occupation that keeps causing the meniscus to tear.

“I mean, I have an appreciation for it,” said Twins manager Rocco Baldelli, whose own career was ruined by a nagging condition in his legs. “On top of all the physical work that [Jason] put in to get back on the field, he’s not as young as he used to be. … There’s a mental and psychological component to rehabbing, a fear when you miss a year and don’t face high-level competition. I have respect for guys who are able to regroup.”