I too had a grade 4 lesion on my medial femoral condyle that they did microfracture on on Feb 25, 2008. If I remember right, it was about 2cm x 1cm in size, so a pretty big one. I also had one done at the same time in the trochlear groove. I just underwent another scope of that knee on Aug 1 to see what's going on since I'm still in pain, cannot straighten my knee fully when walking, etc. I wasn't as fortunate as you though in that the large lesion I have isn't healing right. It looked pretty bad during the surgery - I was awake and watched the surgery. My surgeon said that the new fibrocartilage that was growing in the microfracture site wasn't even good cartilage. So, now it seems my next step will be an unloader brace and possibly a high tibial osteotomy in the future. I'm only 38 years old, so they won't even consider TKR yet. Glad to hear your microfracture sounds successful!!!