Workers Compensation vs. Private Insurance?

I had slipped on ice while at work on 2-1-11. Reported this to my employer directly after fall. Went to Employee health had x rays that same day and then they scheduled a follow up in two weeks. At the follow I stated my knee still had been bothering me. Employee health set me up for therapy. During this time I continued to perform full duty as a home health nurse. Knee had hurt this entire time always in the same place, applied ice and took Ibuprofin to help with this pain so I could continue to work. Sent for an MRI then a follow-up with a surgeon. Surgeon stated this was a congenital problem that that the fall had inflamed, he said he wanted to try therapy first then follow up with him in 6 weeks. Also gave me a brace for the instability of my patella. 3 weeks later at a wedding before the reception my patella dislocated. Went to er. Followed up with surgeon. He stated I need surgery now, considering this is the second dislocation and this one is worse, it will happen again. Workers Comp now wants to close my case because this happened at the wedding and not at work. Meanwhile I have always been under their care, still in therapy, wearing brace, still complaining of pain, swelling and numbness. Workers Comp never contacted my surgeon they only talked to HR and employee health. My question with this is what should I be doing? Is this still a WC case? Any suggestions on this case? Thank you!