Can somebody give me advice my knee is catching and popping after knee surgery?

How long after? Depends how long ago surgery was, and nature of surgery. If in early post op period (1st 4-6 wks) would not be too concerned as may resolve over time. Also if not associated with pain and not activity limiting likewise would not be concerned. If painful and fair amount of time since surgery repeat MRI may be warranted to ensure no meniscal or cartilage tearing to explain continued symptoms.