I'm a competitive runner that was recently diagnosed as having arthritis in the patellofemoral compartment.  The MRI report states that a portion of the lateral facet has complete cartilage loss.  I could run on it but pain almost certainly develops during a run.   Reading up on PF arthritis, it sounds like its origin can be a number of things, namely: alignment issues, OA, trauma, or obesity.  My orthopedist said one my legs is slightly longer than the other and my pelvis is slightly tilted.   Does anyone know if these things combined with running can cause PF arthritis?  I've been running 60-80 miles a week relatively pain free for the last 5 years.  Is there anything that can be done in physical therapy (like a running gait analysis) that might be able to assess the origin of my condition?  I'm thinking that I might have some alignment issues. I probably will give up running because of this but I'm concerned about whether this is arthritis is going to be isolated in the PF area or whether it my progress to other parts of the knee.