-- Vidal Lopez, 19, lost both his legs above the knees from a car accident in the summer of 2016 in Mexico.
At the time, doctors told Lopez's family that he might not make it, let alone be ever able to walk again.
But over the course of the past few months, Lopez proved doctors wrong — and last week, he walked again with the help of new prosthetic legs with microprocessor knees that were donated, in part, by the foundation of Boston Marathon bombing survivor Heather Abbott.
Abbott, who lost a leg in the 2013 bombing, told ABC News today that she started the Heather Abbott Foundation in December 2014 to help provide customized prostheses to those who have suffered limb loss through traumatic circumstances.
"Prosthetics that really allow you to live life as you had before losing a limb are typically not covered by health insurances and are extremely expensive," Abbott said. "That really inspired me to start the foundation."
Though Lopez got mechanical prosthetic legs and knees in November, they only allowed him to stay upright and walk at one speed, according to his prosthetist David Rotter, who works in Chicago.
Rotter told ABC News the mechanical prostheses limited Lopez's mobility, keeping him dependent on ambulatory aids and a wheelchair.
So Lopez applied for a grant to get better prostheses called microprocessor knees through the Heather Abbott Foundation, Rotter said.
The microprocessor knees provide a more sophisticated way to control prosthetic knees and legs, Rotter said. Sensors in the knee detect changes in the environment, such as differences in terrain, that will allow Lopez to walk with a more stable gait and at any speed he desires.
Lopez received the microprocessor knees on Feb. 6. Within four days, he trained himself to walk with them without any help, according to Rotter.
"To go from a wheelchair to that level of use is pretty extraordinary," Rotter said. "It usually takes weeks or months to get used to them."
Lopez told ABC News that he credits Abbott's foundation with giving him the hope and determination to get back on his feet so quickly.
"In a couple of weeks and months, I hope I'm going to walk even better," he said. "Then, I want to return to college next summer and become an engineer."