I had revision surgery on my hip 2 1/2 years ago due to metal poisoning. Since then I have had 4 dislocations. They tell me I need to have a new cup replace the plastic cup that was put in last time. My surgeon said that I need a plastic cup that will constrain the the ball of the femur so it won t slip out as easily, and it still might come out, in which case I ll need another surgery to put it back in. Is he right? or is there another option?