Kyphosis, yes, that is what he really had. I do know, I was actually “in the trade” so to speak. And he wasn’t a traditional hunchback but he probably had a lot of spasm. I would think they would be more likely to call him “crooked” or whatever the parlance at the time was.
I saw the spine, it looked like a really good scoliosis that looked uncomfortable to live with. It was pretty severe. Maybe in some people it might not be too obvious but my guess is it had to be at least somewhat so. Who knows how it manifested in his actual walk and balance? He was a warrior, had to be able to move, the body can compensate pretty well for such things - but that does not mean they are not easily spotted - usually a high shoulder, uneven hips - first things chiropractors look for.
The interesting thought is, when did it come on? If it was childhood, his mother would probably have been blamed. That is the way things worked - mothers at the time were blamed for the way the kids physically turned out. A lustful thought might produce a monstrous child. That’s why they would enter periods of “confinement” while pregnant. It’s why poor Anne Boleyn ended up dead when she had stillbirths - she MUST have done something wrong to kill the King’s sons. Childhood scoliosis often has other genetic abnormalities, like missing organs.
If he was older, it may not have been noticed until he was later teens. Then what evil sin did he commit to bring it on? Hmmmm? We don’t think that way, but people at the time sure did. They had tons of spies in chambers. They talked about royalty - a lot. Royalty was the celebrities of the day. Something like a “crooked” king was must have been great fodder for the masses.
There is absolutely nothing to conclude that Richard was thought “evil” in his time because he may or may not have had a raised shoulder - this is a cliché about a time that was really much more sophisticated than commonly thought. In fact, the brilliance of the nobility and royalty is quite remarkable. The more I read about them the more I’m impressed with their genius.
There are no contemporary accounts of Richard being deformed. In fact, the reconstruction of his face shows a quite comely individual. His physique is considered gracile. He was small and fine boned. He was a fierce warrior who preferred a battle ax to any other weapon. He was also a fine horseman.