Why Does Your Knee Snap and Pop?

Why Does Your Knee Snap and Pop?


Snapping and popping knees bring many patients in the door. Some patients have painful snapping of their knee and some simply have snapping with no pain. Some patients note a history of trauma, some do not recall any injury. While not all cases of knee popping require treatment, some do. Let’s explore what are some of the more common reasons that our knees will snap and pop.
What Makes Our Knees Snap and Pop?
Our knee joint is composed of three bones — the end of the femur or thigh bone; the top of the tibia or shin bone, and the patella, or kneecap. The knee is supported or held together by a number of ligaments. The knee moves because of a number of large strong muscles and tendons. The force across the knee is borne by the medial and lateral menisci, which are two cartilage discs that protect the cartilage surfaces of our knees.
All of these structures can be damaged by activity, trauma, injury or simple degeneration. Many injuries to the knee structures mentioned above can causes snapping and popping of your knee.
Most common reasons your knees pop or snap:
• Chondromalacia- Is a condition where the cartilage under your kneecap is starting to degenerate. As the cartilage degenerates the surface can become rough. That rough surface will rub against the femur and cause snapping, clicking or popping.
• Meniscus tears: The two menisci are stuck between the end of the femur and top of the tibia. They are C-shaped discs that help support the knee and protect the cartilage surfaces. Because a meniscus is between the two bones, a torn meniscus with a loose flap can easily cause the knee to snap, pop or crack with turning, twisting and squatting.
• Cartilage Defects:

Note the large hole in the cartilage
The bones of our knee are covered by a thick smooth layer of “articular cartilage”. Injuries and certain diseases like Osteochondritis Dessicans (OCD) can cause defects or holes to occur in the cartilage layer. If you have a cartilage defect then the surfaces of your knee are no longer smooth, and your knee is likely to pop, snap or grind.
• Patella Instability: The patella sits in a groove on the front of your femur. It should sit perfectly centered within that groove. Sometimes the patella tilts to one side, or sometimes it slides out of the groove completely. This is a very complex issue that requires an evaluation by an Orthopedist who specializes in disorders of the patella and and mal-tracking or instability disorders.
• Osteoarthritis: By definition, osteoarthritis implies a degeneration or “thinning” of the cartilage you have on the ends of your bones. Normal cartilage is incredibly smooth. As the arthritis progresses the cartilage will undergo changes that cause significant roughness to the surfaces of the knee. Sometimes the cartilage can even peel off the bone leaving a defect or crater in the cartilage. As the ends of your bones move on one another, any irregularity in the surface can cause snapping and popping within the knee.
There are many more less common causes of knee snapping and popping. The issues mentioned above usually cause painful snapping and popping within the knee. If you have painful popping, snapping and swelling you should see your doctor.
Many of you will have painless knee popping and snapping. Sometimes our knee pops or snaps for no known reason. In many situations it is simply “normal” and no treatment is necessary more