Have you ever experienced “creaking”, “popping”, or “grinding” at your knees with bending, squatting, or going up/down stairs? It’s a common question asked in clinic, and it can be quite a discerning thing if you’re unsure of what it means.
This “creaking” type sound that is most commonly heard at the knees is clinically referred to as crepitus. Research on the topic of crepitus is quite slim, but a recent editorial, that I’ll try and sum up, provides a nice compilation of it all. On the whole, researchers and practitioners are still on the fence as to what exactly causes crepitus. One theory is that it may be caused by the jerky movement of the patella (knee cap) over the femur as it slides within its groove while being compressed by the quadriceps. This choppy movement creates vibration which results in that creaky sound. Another theory is that the articular surface on the back of the patella can fissure and become less smooth with normal aging. This in turn results in irregularities along the surface, producing vibrations (creaking) with compression and sliding. Lastly, it could be the result of gas bubbles within the synovial fluid (joint juice) that are compressed creating the “popping” sound. Most likely, it’s a combination of the above with other components that haven’t yet been documented.
Looking past the cause, the biggest thing to know about crepitus is that unless it is paired with pain, swelling, or a loss of function, it’s really nothing to worry about. In cases where it is paired with those associated symptoms, a variety of knee pathologies could be at work (meniscal injuries, osteoarthritis, osteochondral defect…) and should be checked out. However, crepitus on its own is more than likely not due to any harmful changes at the knee, and is in fact quite normal. So if you have a bit of “creaking” or “crunching” in your knees without any of the other symptoms stated above, keep on keeping on and don’t let it limit your activity. If you have any questions for our practitioners, or would like to book in an appointment, don’t hesitate to contact us at firstname.lastname@example.org