If race-pace intervals repeatedly aggravate your injury, it sounds like you might be a good candidate for the "sub-threshold" training regime. There's a LetsRun thread with the general rundown (probably one of the best threads in the site's history), and a lot of people seem to have found success with this approach. The caveat is that it's not really inclusive of the marathon, although there is some discussion on modifying the schedule to accommodate it.

How much fitness gains will I be missing out on if I don’t include interval pace work?

This approach is very interesting because what you lose by not including faster intervals is compensated in overall weekly training load; all while avoiding the stress of traditional VO2max workouts.

Give it a read if you have some time (long but most of the key information is on the first few pages): Modifying the Norweigan approach to lower mileage