Knee Replacement Problems and Risks

Knee Stiffness

One of the most common problems people experience after knee replacement is a stiff knee joint. This can cause difficulty with activities that require a lot of bending, including going down stairs, sitting in a chair, or getting out of a car.

Management of a stiff knee joint after replacement may include appropriate physical therapy and pain management, as well as minor surgical interventions, and, more rarely, revision surgery, or a second knee replacement.

Risk factors for having a stiff knee joint after knee replacement include:

• Having a stiff knee joint before surgery
• Having a previous knee surgery
• Having another condition, such as diabetes, a lung disease, or depression
• Not having appropriate pain management and/or physical therapy after surgery

Clicking or Clunking

Because artificial joints are made of metal and plastic, it is not uncommon to hear clicking, clunking, or popping when the knee bends back and forth. In general, noise without pain is not usually a problem.

Some potential causes of clicking, clunking, or popping include:

• Inflammation in the connective tissue that lines the inside of the joint
• Implant design
• Implant breakage
• Soft tissue moving over the implant

In situations where knee pain or swelling is accompanied by these noises, it is a good idea to contact your surgeon. 

Wearing Out of Implants

Over 90% of knee replacements last longer than 15 years. However, in some cases they can wear out and a revision knee replacement may be necessary.

Knee replacements are more likely to wear out if:

• A younger, highly active individual has the surgery done
• An individual participates in high impact activities, such as running, football, and tennis
• An individual carries extra weight, which can place more stress on the implant

Infection

Infections are a serious complication of knee replacement. However, they only occur in less than 2% of individuals who have had this procedure.

Knee replacement infections are generally separated into early and late infections:

• Early infections occur within six weeks of the original surgery. They're typically the result of skin bacteria entering the joint at the time of surgery. Treatment may involve surgical cleansing of the knee joint with appropriate antibiotics administered for several weeks or months.
• Late infections occur at least six weeks post-surgery. These are usually caused by bacteria in the bloodstream finding their way to the knee joint. These infections can be difficult to cure and typically require the entire knee replacement to be removed.

Blood Clot

Blood clots commonly occur in the large veins of the leg after knee replacement and can cause pain and swelling. In some circumstances, the blood clot can make its way to the lungs. This condition, known as a pulmonary embolism, can lead to serious and potentially life-threatening problems.

To decrease the risk of a blood clot, individuals may be:

• Placed on blood-thinning medications
• Shown how to stimulate blood flow in the leg muscles with specific foot and ankle movement
• Given support hose or compression boots to wear to help with blood circulation