English Translation
It was because he was injured that he decided to return to America.
Unnatural and excessively wordy word-for-word translation… I would propose:
A) 彼は怪我をして、アメリカ帰国を決心した。（きこくをけっしんした。）
B) 怪我のせいで、彼はアメリカへの帰国を余儀なくされた。（きこくをよぎなくされた。）
Alternative sentence A implies that he had been already weighing the idea of returning to US before the injury. But the injury finally pushed him to do so.
Alternative sentence B, on the other hand, suggests that he didn’t want to return to US at all, but he had no choice due to the injury. 余儀なく means “there is no room for reconsidering”. So, the injury forced him to return to US.