He was in a cast that covered both of his legs. And after six weeks, he graduated to a wheelchair, where he sat for 14 long months.
Today, Aubuchon can not only walk, but he competed in the semifinals of Major League Baseball's Pitch, Hit and Run competition -- the official youth skills competition of MLB.
Kids ages 7-14 participated in local competitions, with winners moving on to sectional competitions. Then, the top performers from Kansas, Nebraska and Western Missouri (like Aubuchon) were invited to compete at Kauffman Stadium for a chance to go to the 2010 All-Star Game in Anaheim.
Aubuchon's road to the semifinals was unlike that of any other competitor. He was just eight years old when he developed a severe limp in his leg. Initially, his parents thought he had pulled a muscle, but as the problem persisted, they took him to the doctor.
"Alex had a really bad limp, so we kept taking him to the doctor to see what was wrong," his mother, Shelly, said. "At first, we just thought he had pulled a muscle or something. They took X-rays and didn't see anything. So finally, we took him to our pediatrician, and he said, 'OK, there is something else wrong here.'"
Though X-rays were negative, the Aubuchons took their son to a pediatric orthopedic surgeon. Shortly after, Alex was diagnosed with Perthes Disease, a rare ailment found only in children where the head of the femur loses its blood supply for an unknown reason and disintegrates.
The femur will regenerate itself in time, but to regain its proper form, the leg has to be completely stable. To ensure proper healing, Alex was put in a cast that completely immobilized him for six weeks. After the cast was removed, Alex was in a wheelchair for 14 months while his femur grew back.
"It wasn't fun," he said. "I was very big with sports, very active. It kind of binded me for awhile."
Alex missed out on two seasons of Little League while he waited for his leg to heal. For his mother, it was devastating to see her son miss out on his favorite thing.
"It just killed him," she said. "He'd be sitting there in the sun in his wheelchair watching everybody else play. It was just terrible."
His road to recover was long, but on Saturday morning, Alex was running all over Kauffman Stadium. He stepped up to the batter's box and took a few swings. He tested his accuracy as he pitched to a target. He even played catch in the Royals' outfield -- all without any pain or assistance.
"Incredible," Alex said of the experience. "It was just amazing that I made it here. I get to represent my town. After everything that happened and being here now, it's just incredible."
Alex's father, Ray, could not have been more proud of his son -- not only for overcoming Perthes, but for doing it with a smile on his face.
"Alex takes life as it's given to him," Ray said as he watched his son take pictures in the Royals' dugout. "If we all tried to live our lives a little more like Alex did, we'd all be a lot happier."
Playing in a Major League ballpark made Alex's dream of playing in the big leagues just a little more of a reality.
"I want to play Major League Baseball," Alex said. "When I had Perthes Disease, I felt like I couldn't do that, but now it's wide open. I can still do these things to try and become a Major League Baseball player."
Samuel Zuba is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.