I've Had Been Having Knee Dislocation Problems For Years. I'm

I've had been having knee dislocation problems for years. I'm post MPFL surgery (4 years) and have been doing all my required exercises. My leg feels strong in the gym but I've had two subluxations while iv stretched in bed in the morning time. My Doctor is saying he wont operate until my mpfl ruptures completely but I don't know what else I should do. All the PT in the world does not seem to be working and I'm scared to go skiing this year.