popping or clicking joints I the abscence of pain are not necessarily anything to worry about, many people have these. if the popping is painful then it should be further investigated.
the symptoms you are experiencing in patellofemoral joint sound very much like arthritis
. this would be common many years after patella
realignment surgery. an X-ray should be able to confirm the diagnosis. treatment would begin with antiinflammatory medication and physiotherapy
and could progress to surgery if your symptoms are severe enough.