Scans revealed that Brendan had a condition called osteochondritis dissecans, in which part of the bone in a joint doesn’t get enough blood and weakens — or worse. “Essentially half of Brendan’s elbow was dead from a lack of blood supply,” says Jon-Paul DiMauro, MD, a pediatric orthopedic surgeon at Cohen Children’s Medical Center.

Part of Brendan’s elbow — the capitellum, which is the knoblike protuberance on the outside of the elbow — had completely detached from the rest of the bone.

Osteochondritis dissecans is often caused by repeated stress or trauma, and it can lead to the bone and cartilage actually breaking loose. That’s what had happened to Brendan.

To complicate matters, Brendan had a stress fracture in his arm — and unfortunately it ran through the growth plate, the area in the middle and end of long bones where new bone is created. A growth plate fracture usually heals without a problem, but sometimes it can interfere with future growth.

Dr. DiMauro frequently sees osteochondritis dissecans in joints, most often in the knees or ankles of young gymnasts. But Brendan’s elbow was the worst case he’d ever encountered.

Kira McNulty, Brendan’s mom, remembers that Dr. DiMauro made the difficult news easier to absorb. The diagnosis was frightening, she says, but his experience and openness reassured her. And she appreciated his ability to connect with kids, simplify things and even inject a bit of humor.

“He has a way of giving them a sense of safety for what’s about to happen,” she says. “Kids who are hurt just want to feel normal, and the fact that he can do that for them is really a gift.”

Brendan’s surgery was scheduled for just before Thanksgiving. In the operating room, Dr. DiMauro encountered a roadblock almost immediately. As he entered the elbow through a centimeter-long slit in the muscle that attaches the humerus and ulna — the long bones of the upper and lower arm — Dr. DiMauro discovered that things were even worse than he’d thought. “It was like something I’d never seen, or even read about, in my life,” he says. “The capitellum was basically a huge, free-floating piece of cartilage and bone inside his elbow.”

Dr. DiMauro worked for 90 minutes to return the capitellum to its proper position and fasten it against the bone. If all went well, compression would help keep the pieces together, and the small wounds caused by the screws would encourage blood flow to the area and promote bone growth.

Brendan went home in a hard cast with strict instructions to keep his arm completely still for a few weeks. Then he started twice-weekly physical therapy.

It was a frustrating time for the eighth grader. He watched the basketball season, and then the lacrosse season, come and go. After three months, Dr. DiMauro repeated the scans on his elbow. Everything remained in place, but the capitellum hadn’t completely grafted itself back onto the bone. That worried Dr. DiMauro. “We didn’t know if it was going to heal or if we were going to have to start thinking about damage control,” he says.

When the possibility of another surgery to stimulate healing came up, Brendan was distraught over the prospect of another delay. It was one thing to lose a season of competitive sports, but did that mean he couldn’t even toss a ball around with his friends? “Will I not even be able to swing a golf club?” he asked his mother. “Is my elbow going to be messed up for the rest of my life?”

Then more bad luck for Brendan led to a positive outcome — Dr. DiMauro calls it “serendipity.” A few months after the follow-up imaging, Brendan got a little too active with some friends and broke his right hand. Fortunately, he didn’t damage the elbow repair, but he needed another full cast, for eight weeks. And that immobility turned out to be just what the doctor ordered. “He shut down all activities,” says Dr. DiMauro. “That gave his elbow enough rest to completely consolidate.”