Clicking Noises From a Knee Replacement

What They Mean and When to See a Doctor

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Many patients who undergo knee replacement surgery will describe noises that come from their replaced joint. People commonly mention a clicking or clunking coming from their knee replacement when they walk, and they often worry that something is wrong with their knee replacement. Is it a problem to hear clicking after knee replacement surgery?

What the Clicking Means

While any clicking following a knee replacement can be unsettling and even annoying, it is generally not a problem. It is not unusual for people to be able to hear or feel their knee replacement after they have surgery. Usually, a little reassurance that nothing harmful is taking place is all that is needed in these situations. Your surgeon can examine your knee, and possibly obtain tests such as an X-ray, to ensure nothing is wrong with the implant.

Noises can come from a number of possible sources, including the metal and plastic implants, tendons, and fluid around the knee. Determining the source of the noise is something your surgeon can help you with. However, take comfort in that fact that many patients describe clicks and other noises that come from their knee replacement.

With that being said, there are specific circumstances in which clicks and other noises should be investigation.

As a rule, you should see a doctor if the clicking noises are accompanied by pain, swelling, or joint deformity, or if a new noise develops out of the blue. Generally speaking, you would expect noises to diminish over time, not increase.

Prosthetic Knee Components

Most knee replacements are made of four separate parts. While there are some subtle variations, the most common knee replacement has two metal parts and two plastic parts. Among the four parts of a knee replacement are:

  1. The femoral component is the metal cap that is fitted to the end of the thigh bone, the femur. The femoral component is a U-shaped cap that covers the end of the bone, wrapping around the front and the back. There are different shapes to the femoral component that can be based on patient size, and how much stability is needed to reconstruct the normal knee function.
  2. The tibial component is also made of metal, and sits on top of the shin bone, the tibia. The tibial component has a part that extends into the hollow center of the bone to support the flat top tray of the tibial component.
  3. The patellar component is an artifcial extension of the kneecap. while not every patient ends up with this component, those that do will have a plastic (polyethylene) patellar component. This part replaces the inner half of the kneecap. The kneecap itself is not replaced.
  4. A polyethylene spacer is a plastic appliance inserted between the metal femoral and tibial components. This allows for smooth movement of the knee joint back and forth. There are variations in the shape and thickness of the polyethylene components to match each particular patient and situation.

    Each of these implanted parts is held within the bone either with cement or wedged tightly into place so that bone can grow into the implant. Different implants are designed to be held in place in different ways. Moreover, your surgeon may have a preference for a particular type or brand of implant to use.

    Most noises are the result of the metal and plastic components rubbing against each other. Because the components are not connected but rather held in place by the body's own muscles and connective tissues, the noises will often settle as the tissues grow around them.

    Unfortunately, there is no way to know how long this will take. Knee-strengthening exercises can sometimes help, particularly weighted leg extensions. If the problem is aggravating, consider seeing a physical therapist who can help you develop an action plan to build muscle and maintain flexibility in and around the joint.

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