I am 54 years old. In 2000 I had a patellectomy on my right knee after having 11 dislocations.I have trochlear dysplasia also.On Sat my right knee gave out,fell down stairs and was taken to ER by ambulance with the WORSE pain ever on the left side of the knee.I don't see an ortho until Feb 16th.Has anyone experienced this?Any thoughts??? Could this be a dislocation of the extensor mechanism? I have a lot of swelling on the left side and black/blue on left and underneath. Looking for any help and thoughts...thank you!