Off-topic post to share a site I thought might be useful:
It’s supposed to be a free site on which you can record yourself doing speech practice and send it to a coach who will evaluate it and give you comments. I’ve never tried it, but it seem interesting. And you only need to pay if you want ‘unlimited’ coaching, because it’s a non-profit, so they just need money to keep the site running. Japanese is one of the languages.
Guess I’ll do J
だったら なんで 手術 なんか した んだ……？
be-TARA why surgery something-like do-past [emphasis/attention]
In that case, why did (they) do something like surgery…?
だったら: if + to be (so something similar to ‘if that’s’). Can be combined with other words to form a full conditional block e.g. (This came to mind because of the manga’s contents) 医者だったら、なんで助けてあげなかった? = If (you)'re a doctor, why didn’t you help (that person)? Heads-up: ったら (with the little っ) can also be used to reinforce a statement (especially an order), or to emphasise one’s focus on a person/thing e.g. あなたったら、いつもこんな風ね！= You, I say, you’re always like this, huh? 早くこいったら！= Come quickly, I said!
なんで: Written with kanji, it would be 何で=what + [means]. Thus, it means ‘by what means/based on what etc’ = ‘why’
なんか: it means ‘something like’, but it can also have a slightly condescending connotation. Here, it might help to express Saitou’s disapproval and anger towards the pointless surgery.