The c. 1275 miraculous transplantation of a leg

I find it hard to imagine where stories like this come from, especially in this level of detail - apparently the leg being transplanted here was from a freshly dead Ethiopian.  The episode is described by Jacobus de Voragine in 1275, translated into English by William Caxton in 1483:

“Felix, the eighth pope after S. Gregory, did do make a noble church at Rome of the saints Cosmo and Damian, and there was a man which served devoutly the holy martyrs in that church, who a canker had consumed all his thigh.

“And as he slept, the holy martyrs Cosmo and Damian, appeared to him their devout servant, bringing with them an instrument and ointment of whom that one said to that other: Where shall we have flesh when we have cut away the rotten flesh to fill the void place?

“Then that other said to him: There is an Ethiopian that this day is buried in the churchyard of S. Peter ad Vincula, which is yet fresh, let us bear this thither, and take we out of that morian’s flesh and fill this place withal. And so they fetched the thigh of the sick man and so changed that one for that other.

“And when the sick man awoke and felt no pain, he put forth his hand and felt his leg without hurt, and then took a candle, and saw well that it was not his thigh, but that it was another. And when he was well come to himself, he sprang out of his bed for joy, and recounted to all the people how it was happed to him, and that which he had seen in his sleep, and how he was healed.

“And they sent hastily to the tomb of the dead man, and found the thigh of him cut off, and that other thigh in the tomb instead of his. Then let us pray unto these holy martyrs to be our succour and help in all our hurts, blechures and sores, and that by their merits after this life we may come to everlasting bliss in heaven. Amen.”

Previous posts in the vintage medicine category:

Anoint the gums with the brains of a hare: advice from c. 1450 on soothing a teething baby.

Advice from c. 530: How To Use Bacon, including for medicinal purposes such as "thick bacon, placed for a long time on all wounds, be they external or internal or caused by a blow, both cleanses any putrefaction and aids healing".

Mostly weird, and some not so weird, medical treatments from the old days, including this:

How to Stop Bleeding, 1664:

“To Stench a Bleeding Wound: Lay hogs Dung, hot from the Hog, to the Bleeding Wound.”
~Samuel Strangehopes, A Book of Knowledge in Three Parts (166[4])

Dubious medical device du jour - the prostate warmer.

Advice from 1380: How to Tell if Someone Is or Is Not Dead, with bonus Monty Python.

How to Slim Down in Fourteen Days: Advice from 1595.

Urine-drinking Hindu cult believes a warm cup before sunrise straight from virgin cow cures cancer, baldness.

Wellcome Library, via Retronaut.