My knees have, on occasion, in the past few years become stiff and a little crackly, but nothing that has ever alarmed me. Now I have been noticing the grinding, rice crispies in milk sound when I come up from a squat or just from sitting on the couch regularly this week. It's not pretty, but there is no pain so I haven't been too worried about it. It's just annoying as anything at this point. So, I just did a bit of research and found the following that I thought I would share. I always stress to my clients to pay attention to their bodies and if they really feel they should not do something or they should rest then they should listen to their bodies and do so... Here is what I found: "In the clinical setting, it is common to feel and hear the crunching under the kneecap. This crunching, known as crepitus, is due to increased fluid under the kneecap and/or changes in the cartilage below the kneecap. The initial crunching isn't related to pain because the tissue is not innervated by the nerves. If no nerves are present, pain can not be felt. All of us age and when you engage in endurance events, it is most likely that this crunching will develop. The problem is when this crunching is progressive. As the cartilage breaks down, pain can develop because the deeper tissue is innervated by the nerves. As the tissue further breaks down, more damage can occur. Some reports suggest that the lateral retinaculum (tissue on the outside of the kneecap) becomes irritated and painful. Diagnoses, such as patellofemoral stress syndrome and chrondromalacia patella, have been used to label this crunching when it is painful.
In summary, you should not worry about the crunching but consider it your check engine light. Sometimes if I see the check engine light of my car turn on, I continue to drive without assessing the problem. As I continue to drive throughout the week and the month, I begin to notice that the car is not running well. Eventually, it stops running and I'm sitting in the mechanic's garage. My point is to assess whether there is a cause to the crunching before it can become a problem. Many things, such as hip weakness, VMO weakness, increased Q angle and foot dysfunctions, have been suggested to cause the problem." http://www.beginnertriathlete.com/discussion/forums/thread-view.asp?tid=151490 by 90revolutionspt