Too many miles, too quickly: how to come back.

Tl / dr: how do I re-enter training after too much running?

Context: I broke three ribs at the beginning of May, and stopped all ME / upper body workouts, but kept running. Over the past few years I’ve neglected flat miles for uphill training, and that poor strategy has hurt as I’ve started long runs in the mountains on very moderate terrain. Once a week for the past month, I’ve been running 16 to 20 miles with <7,000′. I was comfortably running for two to three and half hours at a time, but the jump to five hours was premature. On Saturday, in the midst of a 20 miles run, my knee gave out. I ignored dead / sluggish legs in the days leading up to that event. Stupid. I felt much better on Sunday / yesterday, but want advice on how best to restart the 16 or 24 month skimo plan? I have many years of running and skinning and a solid four years of training with your book / principles.