In the lobby of Brigham and Women’s Hospital, a young boy stares at Will Lautzenheiser in his wheelchair. He tugs on his mom’s arm, pointing at Lautzenheiser’s metal legs.

But the observant boy misses what is truly remarkable about Lautzenheiser. It’s the arms and hands he uses to move the joystick on his wheelchair, snap on his leg prosthetics, and hug his friends. These limbs used to belong to someone else. A series of tragedies, medical triumphs, and hard work has turned them into his own.

Lautzenheiser, one of about 80 people worldwide with transplanted arms, can’t fathom what another American recipient told People magazine last month: that he had considered getting his transplants removed. Jeff Kepner said his limbs, swollen and lifeless in pictures, had not lived up to his expectations.

“Never. Not for a moment’’ has Lautzenheiser considered getting his transplants removed, he told STAT. “As soon as I saw them, I thought, ‘These arms are beautiful, and I’m going to do all I can to make them work and keep them healthy and heal them.’ ’’

And work he has.

“Arm transplants aren’t for the lazy,’’ he said.

Patients go into their surgeries fully aware that the procedure is experimental and might not succeed, though 95 percent of the transplanted limbs have had good outcomes, said Dr. ­Vijay Gorantla, administrative medical director of the Reconstructive Transplant Program at the University of Pittsburgh Medical Center. Fewer than 10 of the transplants have had to be removed.

To reduce the risk that the body will reject new limbs, a transplant recipient must commit to taking medication every day for the rest of his or her life.

The surgery is followed by an intense 18 months of occupational therapy to sharpen a patient’s fine motor skills. For Lautzenheiser, who had his operation in October 2014, rehab has been a full-time job. He had his last scheduled occupational therapy session earlier this month, but he will continue with physical therapy to improve his gait.

A filmmaker and college professor, Lautzenheiser was teaching out West in 2011 when he caught an aggressive strep infection that progressed to sepsis and necrotizing fasciitis, costing him all four limbs.

He still needs help from aides and his partner, Angel Gonzalez, especially with buttoning clothes and preparing meals. But Lautzenheiser can now write his name — in handwriting that isn’t much worse than it was before — grasp tiny objects like pegs on a pegboard, and handle his own hygiene. Just a few weeks ago, after forgetting the splints he normally uses for support, Lautzenheiser managed to eat a bowl of ramen unassisted — his first truly independent meal in five years.

“This has restored so, so, so much,’’ Lautzenheiser, 42, says of his surgery. “Your hands are engines of communication and intimacy, and there’s a lot that can be expressed emotionally through your hands — and to have that restored, for me, has been amazing. . . . People going down the street look at me with a lot less pity than they used to.’’

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Finding the right transplant patient is key: someone who has the emotional makeup to do the work that’s required every day for the rest of his or her life. The psychological aspects of success are far harder than the technical aspects of the transplant itself.

“Transplanting a limb is mostly a feat of organization rather than a feat of surgery,’’ said Dr. Simon Talbot, director of upper extremity transplantation at the Brigham, who helped lead Lautzenheiser’s care.

There were 35 people involved in Lautzenheiser’s nine-hour surgery. And they had to be ready to operate within a few hours. Lautzenheiser was lucky. After a year of testing and consultations with plastic surgeons, orthopedic surgeons, transplant experts, immunologists, psychologists, and social workers counseling to ensure he would be a good candidate for a transplant, he waited five months for a donor who matched his blood type and physical characteristics.

Talbot, a reconstructive plastic surgeon who has been involved with three double arm transplants at the Brigham and one single arm transplant at Massachusetts General Hospital, said he’s choosy about donors. They have to match the patient’s gender, size, age, skin tone, and immune markers, and the arms have to be in the best condition possible.

“You get one chance at this,’’ Talbot said.

Talbot won’t take arms with tattoos for fear that a family member of the donor might recognize them. Lautzenheiser doesn’t reveal the exact date of his transplant to prevent people from guessing the identity of his donor.

A good match is also crucial psychologically, Talbot said. People look at their hands more than their own faces, and he wants his patients to feel that their limbs belong. Lautzenheiser’s new arms tan faster than the rest of him — otherwise, he said, they’re a solid match for his own.

It’s psychologically damaging to lose limbs, Talbot said, to be different from other people in such a fundamental way. Little children stare. Their parents turn away. “That sense of social isolation is incredibly disempowering,’’ he said.

Transplantation can make people feel whole again.

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Every transplant patient is different, and every procedure has its hitches.

Lautzenheiser had to get a second surgery a year ago to realign his right hand, which was stuck facing upward. There’s still something about his new wrist bone that won’t allow his hand to roll over normally, and he admits that “I fight with my thumb sometimes.’’ Both arms still bulge at the point of transplant, where surgeons overlapped his own muscles with those of his donor.

Lindsay Ess of Richmond, Va., received a double hand transplant at the University of Pennsylvania five years ago. The antirejection medication has been hard on her kidneys. She developed a blood clot in her leg in April, which cost her some strength and fitness. Medication gave her diabetes; steroids left her bloated. And the former model still doesn’t feel feminine enough to be comfortable wearing a dress.

Her doctor, L. Scott Levin, chairman of the department of orthopedic surgery at Penn Medicine, said every transplant is a balancing act, trying to keep the good from outweighing the bad.

There are three basic things that can go wrong with transplant surgery: the recipient’s body can reject the new limbs, their kidneys can be strained by the antirejection medications, and their nerves can fail to grow into the donor’s muscles, Levin said.

If the side effects become unmanageable, surgeons can remove the transplants.

Pittsburgh’s Gorantla had to do just that with one patient: a Marine who lost his hand to a bomb. The man was a phenomenal success in terms of function, Gorantla said. Three years after his transplant, he was using his hands to eat with chopsticks and winning at ­PlayStation.

But young enough to still feel invincible, the man didn’t keep up his daily medications and missed checkups. His body eventually rejected the new limb.

“There is an exit strategy for hand transplantations,’’ Levin said.

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No one knows the outside limit of arm transplants.

Nerves regrow at a pace of about 1 millimeter per day. The less arm that needs to be transplanted, the more likely the patient’s nerves will regrow and give good control over the new hand, says Dr. Curtis Cetrulo Jr., a plastic surgeon at Mass. General.

Doctors used to assume that any muscle control that didn’t come back after 18 months or so would never return. But what they’re seeing defies that assumption. Matthew Scott, the first American to receive an arm transplant, continues to see small improvements 18 years later, said Gorantla, who helped perform Scott’s surgery when he was at the University of Louisville.

“Functional recovery never stops,’’ Gorantla said. “The more you give in terms of physical therapy, the more the possibility of outcomes are.’’

Lautzenheiser still has goals to reach. His next milestone, he said, will be walking — rather than riding his motorized wheelchair — to the nearby movie theater.

He’s now making his first film since the infection that took away his career; he can’t hold the camera himself but will direct and edit. It will be a three- to four-minute tribute to the anonymous man whose arms he now carries and to the family members who decided to transform their own tragedy into such a precious gift.

Shooting started Wednesday.

Karen Weintraub can be reached at karen.weintraub@statnews. com. Follow Karen on Twitter @kweintraub.