Bryant Jacobs' computerized knee joint, worth more than the Nissan Titan truck he recently financed, is among the most advanced pieces of medical technology in the world.

His carbon-fiber foot is the result of decades of research and development.

But the socket that connects all that technology to the stump of his amputated leg works about the same way as ones developed during the Civil War.

Back then, sockets were made of leather or wood; today, they're plastic or carbon fiber. Modern materials can be better fitted to the contours of a patient's residual limb, but the function remains the same for an above-the-knee amputee. The socket is intended to hold snugly around the limb, distributing the load of the user's weight across as much area as possible.

When the fit isn't quite right, or Jacobs wears it too long, he gets sores, abrasions and blisters.

Skin problems that develop under a socket frequently force amputees to take a break from using prosthetics. When that happens to Jacobs, he has to return to his wheelchair.

These challenges are why, just months after learning to walk in his prosthetic leg, the 34-year-old Army veteran is eyeing his next bionic step.

It's a crisp winter morning in Salt Lake City, but Jacobs opts for a loose pair of athletic shorts for an appointment with Erik Kubiak and Jay Agarwal, the surgeons who teamed up for his amputation back in March.

Kubiak and Agarwal are looking for 10 veterans to test an osteointegrated implant they recently developed. If Jacobs is selected for the trial, the implant will connect his prosthetic directly to a stud rooted in the end of his femur.

The Department of Defense, Department of Veterans Affairs, National Institutes of Health and other agencies are eager to know if the Salt Lake City team's implant will work. They're investing millions — and there is far more than that at stake — in the device, described in a patent obtained by Kubiak, Agarwal and six colleagues in February.

"You'd have a rod sticking out of your skin," Agarwal tells Jacobs at the VA hospital in Salt Lake City. "You've got to remember it's not normal for humans to have that. There are animal models for that — antlers, you know — but those are natural parts of their body."

Jacobs listens intently and enthusiastically nods — even when Agarwal describes the potential consequences. If this doesn't work or if an infection takes root, he says, doctors might have to cut off more of Jacobs' leg.

"So tell me why you want to be part of this," Agarwal says.

"It would be nice to get rid of the socket," Jacobs replies.

"You've only been in it for, what, four months?"

"It's already clear that it would be great to be able to get rid of it," Jacobs says. "I want to better myself. To potentially wear my leg 24 hours a day if I wanted to. The socket's good — everything is better than it was before — but I'm ready to be better than that."

Agarwal jots some notes and shakes Jacobs' hand. Until a decision is made, he says, Jacobs should work toward the goals he would pursue if there were no study.

"That's definitely my plan," Jacobs says.

Jacobs hoped to mark the 10-year anniversary of the day he survived the explosion in Iraq by getting back on a snowboard.

That would fulfill a promise he'd made to himself early in his recovery at Walter Reed Army Medical Center.

"For me," he says, "what that would represent is really an achievement of independence that I haven't had before. I feel like, when I can do that again, that will feel to me like success."

As Dec. 3 approaches, two storms have dropped enough snow that most runs are open at the resorts outside Salt Lake City. And Jacobs' strength, stamina and flexibility have improved.

Ironically, his improving fitness has created one of the obstacles he faces as his "alive day" nears. As he's gotten into better shape, his right thigh has shrunk so much that his socket is no longer holding fast.

A 3 p.m. appointment with his prosthetist on the day before the anniversary stretches well past closing time. Lane Ferrin fills Jacobs' socket with plaster, carves it away to make a narrower casting, then shrinks the plastic socket onto the new mold.

That improves the fit, but a new Velcro strap, intended to help keep the socket from twisting under torque, is irritating Jacobs' skin. At 5:30 p.m. — hoping to find a solution that will let Jacobs do whatever he wants the next day — they're still battling to make it work.

Buoyant and talkative when he arrives, Jacobs is growing cold and quiet.

"This just isn't working," he tells Ferrin. "I'm not a fan."

Ferrin removes the strap and makes a few final adjustments to the coupling that attaches the socket to Jacobs' prosthetic knee.

"It's going to feel tighter, obviously, because it is tighter," Ferrin tells him. "Every time we do this it's going to be a little bit like learning to walk again."

By the time Jacobs leaves, it's clear he won't be spending his alive day on the mountain.

If this feels like yet another setback, though, Jacobs is keeping it to himself.

"I'm just not ready," he says. "And that's the way things go. One of the things I've learned is that you really have to control the urge to get your hopes up. I want to be ready and I am willing to work for my goals, but things are going to happen when they happen. If I try to push against that, there's a chance I'll get hurt."

Neither his wife nor his stepdaughters are awake when Jacobs rises, crutches to the bathroom for a shower, disconnects his prosthetic leg from its charger and quietly leaves out the nearby garage door.

He's made the 40-minute trip from his home to the hospital so many times that he doesn't have to think about how to get there. Today, the time is flooded with memories.

Because this is his day.

He remembers the two years he spent in the hospital. He remembers the years of pain and immobility after his return to Utah. He remembers his decision to remove his leg. He thinks about the challenges he's overcome and those that are still to come.

And he remembers the man who died when he survived. Today is David Mahlenbrock's day, too.

Mahlenbrock enlisted after the Sept. 11 attacks. He knew he would be going to war. That was OK with the high-school wrestler from Maple Shade, New Jersey. His brother Chris had joined after high school, "and he had nothing but good things to say about it," remembers their father, Russell Mahlenbrock.

Russell Mahlenbrock says his son left for Iraq with pride and determination — even after learning that his wife, Melissa, was pregnant with their first child.

David Mahlenbrock met his daughter just once, while on leave in November 2004.

Kadence was 10 weeks old when her father was killed.

"If you are reading this, then I've died for our country," the 20-year-old soldier wrote in a letter to the other members of his squad. "I just hope it wasn't for nothing."

That's a question his father does battle with every day.

"I don't mind the fact that what happened to him happened to him," Russell Mahlenbrock says. "That's understandable and acceptable. That is what happens at war and it's something we were both ready to face."

But the turmoil that has overtaken Iraq since the last U.S. combat troops left in December 2011 has left Russell Mahlenbrock in despair. "As I move forward from year to year," he says, "I become a little more bitter."

No matter what Jacobs does on this day, he has this day. There's no way, he says, to explain the depth of his gratefulness.

When he left Ferrin's office last night, he wasn't feeling comfortable in the newly shaped socket. When he slid it on this morning, it felt a lot better.

"Do you have any soreness right now?" physical therapist Bart Gillespie asks when Jacobs arrives at the VA hospital's physical-therapy center.

"No," Jacobs says.

"No soreness at all?" Gillespie pushes.

"No," Jacobs says. "Why do you keep asking me about soreness?"

"I don't know," Gillespie replies. "Every time I see you, you're complaining about soreness."

Embedded in Gillespie's teasing is a gentle reminder: Jacobs' leg is feeling fine.

"Sometimes patients have a hard time seeing how far they've come," Gillespie says. "When you're doing well, sometimes you don't think about how you got there."

Together they take a few laps around the room, work on stepping over objects of various heights, and then head to a nearby stairwell to climb and descend.

"You're doing all of this like it's no big deal," Gillespie says.

"Yeah, Bart," Jacobs says with a sarcastic tone. "Because it's not."

Gillespie smiles and tucks his thumbs into the back pockets of his light blue scrubs. "Yup," he says, "it's not."

The VA serves more than 900,000 veterans of Iraq and Afghanistan, about one-third of the military members who have served in those wars since 2001.

More than a quarter-million suffer from post-traumatic stress disorder. Another half-million fight joint and back disorders. About 450,000 are thought to suffer hearing loss.

Among the wounded, amputees are the minority. The military has counted 1,573 limb amputations between 2001 and 2014. The VA figures another 20 to 30 Iraq and Afghanistan war veterans receive amputations each year in its system.

But amputees are hard to ignore. Jacobs figures there's some responsibility in that fact.

"Most of the time, like when you're walking down the street, you can't know whether someone is a veteran or not," he says.

So rather than feeling offended when people stare at his prosthetic leg, Jacobs thinks his presence might reconnect people to the struggles of veterans.

"Seeing someone who is missing a leg — that's not people's usual experience," he says. "So if they're staring, trying to figure things out, that's fine. Maybe for a minute they remember that there are veterans all around them. And then maybe they'll think about the fact that our obligations as a country don't end when a war ends."

The bottle has been waiting since the day before his surgery.

It's a 20-year Pappy Van Winkle — one of the hardest-to-get bourbons in the world. But when Nick Hoggan presented it to his friend on the eve of the amputation, it was without any of the pomp that typically accompanies a bottle of Pappy these days.

"We can drink this when you're ready," Hoggan simply said.

Tonight Jacobs is ready.

A small crowd has gathered to celebrate Jacobs' alive day. His brothers, Zach and Andy, are there, along with a few friends and neighbors — and everyone's kids. Jacobs' wife, Michele, has bought a cake; it's decorated with an American flag and says "10 years" in blue cursive frosting.

Jacobs bounces from person to person, giving hugs, making jokes. He's been in his prosthetic since 6 a.m., but there's still a spring in his mechanical step.

When Jacobs decides it's time for a toast, he slips the bottle from its red velvet sack.

"I wouldn't be here without all of you guys," he says as eight glasses rise together. "So thank you."

He sips the bourbon. It tastes like a long time coming.

There was a time when just about any excuse for a party was good enough to warrant an all-night bender. These days, Jacobs is usually in bed by 9 p.m.

And on a school night, like this one, he's not disappointed when things start breaking up early. One by one, the guests leave with hugs and handshakes and hearty pats on his back. They thank his wife for the party. They thank him for his sacrifice.

His stepdaughters, Karsyn and Lillian, help clean the house and head for bed.

In his room, Jacobs lines up six pills on the comforter of his bed. He takes them all at once, chasing them with a swig of Gatorade.

"Babe," he calls out to Michele, "do you need me to do anything else before I take off my leg?"

"Go ahead," she says.

He slips off the socket. He rolls down the underliner. He connects his computerized knee to the charger on the wall. It buzzes three times as it begins to power up.

Tomorrow he'll rise and put it back on.

Tomorrow he'll take the next step.