An Arizona grandfather is preparing to undergo an above-knee amputation of his right leg after he tripped and fell while walking outside in Bullhead City during 120-degree heat earlier this month, according to his family.Grant Siler, 72, fell during a walk on Aug. 3 in Bullhead City, causing his body temperature to rise to more than 105 degrees.The familys GoFundMe said Siler was on the ground for an estimated at least an hour before a passerby found him. The fundraiser said he suffered second and third-degree burns in multiple areas of his body, heat stroke and multiple organ shock.HIKERS FACE URGENT GRAND CANYON HEAT WARNING AFTER TEENS DEATH ON POPULAR TRAILHe was then taken to a burn ICU in Las Vegas, where he has been cared for since the incident. When he arrived at the facility, doctors discovered he was suffering from heat stroke and organ shock."He is in constant pain, can barely move, and has undergone two debridements. Also, he will soon need to undergo surgery for amputation, the extent is not yet known," the GoFundMe reads.During surgery, a surgeon found that tissue in Silers right leg was so severely damaged it was unlikely to fully heal, according to an update posted to the fundraiser.Siler is scheduled to have his right leg amputated above the knee on Aug. 31, according to FOX 10 Phoenix.ESPN ANALYST MATT MILLER SAYS HE UNDERWENT LIFE-SAVING AMPUTATION OF LEFT ARM AFTER CAR ACCIDENT"The plan now is to have an above-knee amputation. The Dr's feel he will overall heal faster and have better pain control this way," the fundraiser reads."We can all imagine that after any amputation, the road to recovery is long and hard...physically, mentally and emotionally," it continued.His wife, Vicki, has been traveling one-and-a-half-hours each way to be with her husband as she continuing to work to support the familys financial obligations. The family said the couple will also soon have to face medical bills to help with Silers recovery.The family is accepting donations to help with home renovations, home medical supplies, prosthetics and other added costs.Siler's daughter, Heather Crook, recalled an incident in which he dropped an 80-pound cinderblock on his foot but did not even take a Tylenol."He's hurting really bad," Crook told FOX 10. "He's the 'get up and walk it off' type.""So for him to holler out in pain its really hard to hear. Thats not the kind of person that he is," she added.