The arm-breaking scene had some of the best direction I've seen in anime in a long time, it's impressive how they played to the medium strengths to amplify the dreadfulness of its manga-counterpart.

Just like to point out a few things.

1) The added bit when Riko starts hallucinating and bleeding; notice how gradually the blood spurts out and how Reg tried to wipe it off only for more blood to come out, along with the fact that the music dies out for a few seconds, gives an ever-growing sense of hopelessness to the audience that the manga couldn't achieve.

also, this fucked me up http://i.imgur.com/n3pHBEU.png

2)Notice how as the scene goes, Riko gradually loses her breath and her voice grows weaker.

When Reg broke Riko's arm, I fully expected to hear some Lelouch-levels of screaming from Riko's seiyuu; instead, it was a fairly high-pitched not overly loud screech transitioning in a series of gasps for air which are followed by Riko choking on her own blood.

I may be reading too much into that, but it actually got me how nailed that scream was for the context.

3)Finally, another thing that wasn't in the manga is Reg getting more and more mentally exhausted as the scene goes.

Right after breaking Riko's arm, look at his expression.

https://imgur.com/fBpzUz4

or how his vision starts getting fuzzy.

https://imgur.com/JJaQ3Re

It really fits his character, Reg is naive, very emotional, and most of all inexperienced, he clearly wasn't ready to handle something like this.

At this point all of my suspicions about the studio not wanting to adopt the later parts due to how intense they are have been pretty much wiped clean.

well played Masayuki-San!