Many people complain of crepitus in the knee joint, but most often it is harmless. The “cracking” or “crunching” sound often occurs when standing up or performing some type of exercise. This noise is associated with negative emotions, misplaced fear, inaccurate health beliefs and has even lead to altered mental and physical behavior.
I classify knee crepitus into two categories-
- Crepitus after total knee replacement
- Crepitus in the native knee
Crepitus after total knee replacement
Crepitus following surgery is quite common after knee replacement surgery on the knee joint. This type of crepitus is felt to be self-limited and benign, and no intervention is usually required. The noise comes from two artificial surfaces touching each other. However, if the crepitus is associated with pain, it may be an indication for a minor debridement of the joint to remove any debris. The need for surgery to remove debris after knee replacement surgery is exceedingly rare.
Can anything be done to avoid crepitus after knee replacement surgery?
The incidence of crepitus depends on the design of the femoral component. Modern total knee designs with a smoother intercondylar box are associated with decreased crepitus. These designs also reduce anterior knee pain and are especially useful in patients where the undersurface of the knee cap cannot be replaced. There also is a reduction in knee flexion during stair ascent if there is crepitus after knee replacement surgery. Additionally, I worry about wear in the presence of crepitus but studies have yet to demonstrate wear and deterioration in long term outcomes.
Modern knee designs like Custom knee replacements can be a good option for many men and women, but they’re not for everyone. Patients with severe deformity, ligamentous laxity, prior reconstructive surgery etc are not candidates for custom knee replacement.
Additionally, a repertoire of intraoperative techniques can be used intraoperatively to decrease the risk of post operative crepitus.
Crepitus in the native knee
Crepitus in the knee joint can occur in people of all ages but it tends to be more common with advancing age. The sound may be loud or soft but this is not indicative of the degree of pathology.
Does crepitus signal something ominous in the native knee joint?
Crepitus is harmless if it does not cause pain. Knee crepitus is not associated with poor strength or inferior knee function. However, if crepitus is associated with an injury, or, if there is associated knee pain or swelling, then further investigations are required.
What are causes of crepitus?
There is a theory that popping sounds arise due to the air bubbles passing through the soft tissues and find their way around the knee joint. These air bubbles then mix with synovial fluid and when the knee is bent, the bubbles burst and a cracking sound is heard. While the popping sound may be loud, it is usually harmless.
However, crepitus is also known to occur when cartilage rubs on the joint surface when the knee joint is mobile. This usually occurs when the cartilage is thin and worn out. In this case, medical attention may be necessary.
If crepitus is associated with pain or the knee joint catches, this may be due to a meniscus tear, scar tissue or a tendon passing over a protuberant bony fragment. Swelling and pain of the knee joint with crepitus may be indicative of osteoarthritis, patellofemoral pain syndrome or torn cartilage. In these scenarios, the crepitus may occur while climbing a staircase, or sitting for a prolonged time with the knees crossed.
In patients with pre existing arthritis on radiology, crepitus predicted symptomatic arthritis in future. I therefore feel that crepitus offers an opportunity to identify at-risk individuals. Predictive modeling using crepitus, with radiological findings and longitudinally tracking individuals who have knee replacement later in life is an avenue for future research.
Do I need knee replacement surgery for crepitus?
If you have no pain there is probably nothing else wrong with your knees besides Crepitus. In the absence of pain, you are probably not a candidate to have knee replacement surgery.
How do you protect the knees?
Orthopedic surgeons say that the best way to protect the knee is to warm up prior to exercise. By strengthening the quadriceps, one can decrease the load on the patellofemoral joint and also reduce the risk of eroding the cartilage. Other means of protecting the knee include stretching and wearing suitable shoes. It is also important to maintain a healthy weight to decrease stress on the knee joint.
If crepitus occurs during exercise, one should:
– Not stop but modify the exercise
– Avoid running on hills or inclines
– When cycling, maintain tension on the pedals
– If you are using quadriceps to lift weights, use lightweights and increase the frequency
Can Knee Replacement Help?If there’s nothing else wrong with your knees besides Crepitus then you should probably not have knee replacement surgery.
Custom knee replacements can be a good option for many men and women, but they’re not for everyone.
Generally speaking, custom implants are not ideal for patients who have had prior knee surgery or who have injured ligaments.
Patients who are not eligible for CT scan are also not good candidates for custom knee replacements.