If having a one-of-a-kind bone in your arm means you can't wrestle your older brother, nobody told 4-year-old Mark Blinder.
"Sometimes we get in a fight and they say stop it, and he says it's fun keep it up," Mark's big brother Tony Blinder said.
While Mark's behavior may be perfectly normal, his right arm is anything but.
Last year, doctors discovered a rare type of tumor in the bone. The likely prognosis included amputation -- losing his arm beneath the shoulder.
But then doctors at Lucille Packard Children's Hospital came up with another idea -- it would mean adapting a prosthetic bone device that had never been implanted in someone so young.
"The requirements were a little bit different. It would have to be sturdy enough to last a lifetime, and would have to be small enough to fit inside a 3-year-old's arm," Dr. Lawrence Rinsky from Lucille Packard Children's Hospital said.
"Nobody knew what would happen after the surgery, so we decided to go with it, and give our son a chance to have his arm saved," Mark's mom Alla Ostrovskaya said.
In a delicate surgery, Rinsky and his team removed Mark's upper arm bone and implanted the artificial bone. The parts were scaled down so they could be attached to Mark's existing ligaments and muscle tissue.
"The epiphany moment was when I just tried to see if the skin edges would come together and they wouldn't, and I said, we can do it," Rinsky said.
But while the surgery was a success, Mark's age, just 3 years old at the time, presented another daunting challenge. What would happen to the implant as his arm continued to grow?
To solve the problem, doctors teamed with the manufacturer to include an adjustable piston that could be extended just far enough to match Mark's natural bone growth.
"Actually, there is a turn buckle screw device. You go in once a year with a screwdriver and give it three or four turns, of course making sure you turn it in the right direction, so it goes longer not shorter," Rinsky said.
That means Mark will have yearly surgeries to extend the length of his repaired arm. But his mother believes it's a small price to pay for the ability to live and play like a normal kid.
"I just hope he'll go on as a normal child, and the cancer will never come back," Ostrovskaya said.
Doctors say Mark's surgery presented other challenges as well. Since the cancer had advanced, they were forced to remove the bone, while carefully avoiding any contact with the tumor to make sure none of the cancer cells spread to other parts of the body.
Written and produced by Tim Didion.