Had a heart bypass and valve replacement last year in the Mater Private. VHI paid 38k to the hospital, 5k to the surgeon and 2k to the anaesthetist. (Fully covered.)
Imagine knee op fees similar or lower.
But, yeah, check with the consultant's secretary. I've heard anecdotally that prices are negotiable for people with the 80% coverage but I have no direct knowledge of this. Sounds plausible though. 80% of something is better than 100% of nothing. Consultant gets a good few bob for pre-op and post-op consultations too, at €300 a pop. Business finds a way!