Zion Harvey is the first child to receive a double hand transplant, and he couldn't be more thankful. This story has been circulating for the past week, so no doubt you've seen the headlines.
What most impressed me about this story was the surgical process itself; each nerve and blood vessel from the donor limb had to be attached to Zion's own nerves and blood vessels. The process is difficult enough in an adult, but try performing it in a child. The technique that made all of this possible is called "microsurgery". As a microbiologist, I can appreciate the small things, but I'm totally out of my element when it comes to surgery.
Alexis Carrel developed the "triangulation method" to suture veins together and was awarded the Nobel Prize for it in 1912. Today, microsurgeons use operating room microscopes and micro-tools to perform these delicate surgeries. Needles used to suture veins are small enough to pass through a human hair!
Sources: Time, The Children's Hospital of Philadelphia, Plast Reconstr Surg. 2009 Dec; 124 (6 Suppl): e282-94. PMID: 19952697, Vibe (image)