Traditional prostheses make his legs even, but do not give him the freedom to play. That was a problem students at Purdue University intended to fix.
"I am not going to fall, I know that," said Lucas Resch.
The 5-year-old has Proximal Femoral Focal Deficiency, or PFFD. It is rare birth defect, where the hip bone is deformed and one of Lucas' legs is shorter than it is supposed to be.
Lucas gets around pretty well right now, but his parents knew it would get tougher for Lucas to do the things he loves.
Lucas: "I like to swim. "
Reporter: "Big splashes, or little splashes?"
Lucas: "Big splashes."
The Reschs live in Rhode Island. They spent three years searching, trying to find a solution for Lucas, without making a drastic change.
"Amputation, rotating the leg is another option," said Ned Resch, Lucas' father. "Both options are very invasive, and permanent. "
That was when Ned saw a link on YouTube, where a group of engineering students from Purdue were making a special kind of prosthetic.
"Thank you YouTube, thank you Purdue University and thank you Adapt-IF technologies," said Ned Resch.
Inside the box on Lucas' new leg are steel gears. Lucas' foot slips into the leg, and the gears work as a knee joint.
"In Lucas' case where he has a full-functioning foot and all of his ankle is intact, that is not a normal circumstance and that is why this is such a unique project," said Alex Guerra, Purdue engineering student.
After the work of trying on his new leg was over with, Lucas and his family got a little playtime, on-board the Boilermaker Special.
The Resch family will head back to Rhode Island, but the leg is staying on campus. Purdue engineering students will work to make Lucas' leg lighter, in the hopes of giving him his new leg around Christmas.