Trap Bar is a fine alternative. The main problem I see with RDL's as a replacement is that they don't qualify one of the fundamental aspects of what a deadlift is: a lift that starts from the bottom. I see this as one of the best benefits of the DL, as it requires you to assume proper position and technique before even lifting the weight and this is how we'd lift most things in everyday life.
A deadlift off of blocks would be another viable option, as would be other deadlifts you may not have tried, i.e. Jefferson or Behind the back, depending on what your injury prevents you from doing. Even practicing deadlifting a light K-Bell while you heal up and take a break from the bar would be a solid practice to get you grooving again.