“To be missing the penis and parts of the scrotum is devastating,” Dr. Redett said. “That part of the body is so strongly associated with your sense of self and identity as a male. These guys have given everything they have.”

Jeffrey Kahn, a bioethicist at Johns Hopkins, said that at a conference convened last year by the Bob Woodruff Foundation, which aids injured veterans, wives said that genitourinary injuries had eroded their husbands’ sense of manhood and identity. Most telling, Dr. Kahn said, was that the men themselves attended the conference but did not speak about their wounds.

Although surgeons can create a penis from tissue taken from other parts of a patient’s own body — an operation being done more and more on transgender men — erections are not possible without an implant, and the implants too often shift position, cause infection or come out, Dr. Redett said. For that reason, he said, the Johns Hopkins team thinks transplants are the best solution when the penis cannot be repaired or reconstructed. If the transplant fails, he said, it will be removed, leaving the recipient no worse off than before the surgery.

But can men — and their partners — get used to the idea that their most intimate part came from another man’s body?

The best analogy is hand transplants, Dr. Brandacher said, because hands are personal and distinctive — a transplant that the recipient can see, unlike a kidney or liver.

“I can tell you from all the patients — and I’ve been involved since 1998 — every single one, after surgery, look at the graft, try to move it and they immediately call it ‘my hand,’ ” Dr. Brandacher said. “They immediately incorporate it as part of their body. I would assume, extrapolating, that this is going to be the same for this kind of transplant.”

Dr. Kahn said it was essential that the families of organ donors be asked specifically for permission to use the penis, just as special permission was required for face and hand transplants. It is not assumed that people willing to donate kidneys or livers will also consent to having their loved one’s genitals removed. The surgeons want a relatively young donor to increase the odds that the transplanted organ will function sexually.