Knee replacement surgery is a common and generally successful procedure designed to alleviate pain and restore function in damaged knee joints. More than 90% of replacement knees continue to function well after 15 years, and approximately 82% are still performing after 25 years. While highly effective for most individuals, issues can sometimes arise, leading to a “failed” knee replacement. Understanding the signs of potential failure is important, as early identification can lead to more effective interventions and improved outcomes.
Key Symptoms to Watch For
Persistent or worsening pain is a primary indicator that a knee replacement might be failing, differing from expected post-operative discomfort. This pain may occur around the implant, feel diffuse throughout the knee, or manifest at rest, during activity, or at night. While some discomfort can linger after surgery, new or increasing pain that does not improve with rest or medication warrants medical attention.
Chronic or increasing swelling, potentially accompanied by warmth around the knee, can also signal a problem. Although some swelling is normal after surgery, persistent or new onset swelling that does not subside over time may indicate inflammation or other underlying issues. Such swelling can limit movement and cause discomfort.
A feeling of instability or the knee giving way suggests the joint is not providing adequate support. Patients might describe their knee buckling, feeling loose, or experiencing difficulty bearing weight. This sensation impacts mobility and confidence, increasing fall risk.
Stiffness or a reduced range of motion is another symptom that should not be ignored. This presents as difficulty bending or straightening the knee fully, or a noticeable decrease in mobility over time. While some post-surgical stiffness is anticipated, progressive limitation of movement can indicate scar tissue formation or mechanical problems with the implant.
Audible sounds such as clicking, popping, or grinding within the knee can sometimes be normal after a replacement. However, new, persistent, or painful sounds are concerning. These noises indicate wear of components, loosening, or other mechanical issues.
Signs of infection like fever, redness, or drainage from the surgical site are urgent symptoms requiring immediate medical evaluation. These can appear at any time, even years after the initial surgery. Such symptoms indicate a serious joint infection.
Common Reasons for Failure
Infection is a significant reason for knee replacement failure, occurring when bacteria enter the joint. It can occur shortly after surgery or years later, potentially from bacteria traveling through the bloodstream. Infection causes inflammation and can compromise the bond between the implant and the bone.
Aseptic loosening occurs when the implant detaches from the bone without infection. This is the most common indication for revision surgery, particularly after the first two years post-operation. It often results from gradual wear of implant materials or the body’s immune response to wear particles, leading to bone loss.
Instability arises when soft tissues, like knee ligaments, do not sufficiently support the artificial joint. This can be due to stretching or damage to these ligaments, or incorrect positioning of implant components during the initial surgery. The knee may feel wobbly or give way, impacting balance and movement.
A periprosthetic fracture involves a break in the bone around the knee implant. These fractures can occur due to falls or trauma, or sometimes spontaneously if the bone has weakened around the prosthesis. The implant’s presence can complicate treatment compared to typical bone breaks.
Polyethylene wear is the wearing down of plastic components within the knee replacement over time. This wear produces tiny particles, triggering an inflammatory response and bone loss (osteolysis). The thinning of the polyethylene spacer can also lead to increased instability and pain.
Malalignment, or incorrect component positioning during surgery, can also contribute to failure. Incorrect alignment places abnormal stresses on the implant and tissues, accelerating wear, pain, instability, and early loosening. Precision in implant placement is crucial for long-term success.
What to Do If You Suspect Failure
If you suspect knee replacement failure, do not self-diagnose or delay seeking professional medical evaluation. Your orthopedic surgeon or another healthcare provider is best equipped to assess your symptoms. Prompt action can prevent complications and improve outcomes.
Contacting the orthopedic surgeon who performed your original procedure is a sensible first step, if possible. They possess detailed knowledge of your surgical history and implant type. Prepare for your appointment by noting symptoms, including onset, feel, and what makes them better or worse.
During your evaluation, your doctor will likely use various diagnostic tools to determine the cause of your symptoms. These may include X-rays, blood tests for inflammation or infection, and fluid aspiration from the knee joint for analysis. Advanced imaging like CT or MRI scans may provide more detailed views.
If failure is confirmed, your healthcare provider will discuss appropriate treatment options. While revision surgery (replacing components) is a common solution, non-surgical options may also be considered based on the cause and individual circumstances. The specific course of action will depend on the diagnosis and the patient’s overall health.