to worry or not to worry, that is the question. 2 words "Scar Tissue"or Impingement Syndrom. The cartilage in you knee acts as a cushion to keep the two ends of your bones from rubbing. The creaking is either inflamation or the dreaded "scar tissue" from the cartilage being rubbed and squished to much. Only a doctor can tell you which. If its just inflamed - ice motrin and rest. Scar tissue - well you can either lower your activity and see if it gets better or the Doc can hook up the old Hoover and suck out the bad stuff. I have it in both shoulders and both knees. Go see a doctor and please rest your knee so it doesn't get worse!!!