Aseptic loosening of prosthetic knee replacements caused by bone cement failure has been an ongoing problem, according to recent lawsuits.

“Aseptic” means there is no bacterial infection to which the prosthesis failure can be attributed. These failures appear to be linked to use of high viscosity cement (HVC), which saves the surgeon time in the operating room – but according to some research, HVC may have less holding power than low or medium viscosity bone cement.

Joint failure due to bacterial infection is relatively rare; most cases are caused by the bone cement failing to adhere to the bone surface. While the treatments for these failures are quite different, the symptoms are similar.

What follows is a discussion of symptoms that may indicate that a total knee arthroplasty (TKA) has become loose and is in danger or failing altogether.

The First Symptom: Chronic Pain

Pain in the joint is the first sign of loosening, whether due to bacterial infection or bone cement failure. This pain may be accompanied by swelling. It may be localized in one particular area, or be felt all over the knee. Usually, there is a significant decrease in mobility, resulting in stiffness and/or instability, affecting the patient’s ability to walk unaided. This may occur within days, weeks or several months after the initial surgery.

Bone Cement Failure vs. Infection

In addition to persistent or chronic pain of the knee, there are other, less outwardly-visible symptoms that can affect other parts of the body. However, symptoms associated with bone cement failure are different from those caused by bacterial infection.

In the case of infection-related, or septic loosening, there will be redness around the joint, indicating inflammation as the body’s defense mechanisms go into action. This can also be accompanied by a low-grade fever and all-around fatigue, as are common with bacterial infections. As noted earlier, septic loosening is rare; the infection usually responds to treatment with antibiotics and irrigation of the surgical site.

When the loosening is caused by failure of the bone cement, the patient may develop symptoms of toxicity, which includes hypoxia (oxygen deprivation) and hypotension (dangerously low blood pressure). This can occur as a result of applying the cement, which is done with a syringe. Occasionally, the cement may make its way into adjoining tissues and blood vessels as well as the nervous system.

More serious indications of bone cement implantation syndrome include sudden loss of consciousness, arrhythmia (irregular heartbeat) and the formation of blood clots (thrombus). These conditions can lead to heart attack, stroke, and even death.

Are There Alternatives to Bone Cement?

“Cementless” TKA is available, and generally last longer and are more reliable than those relying on bone cement. However, patients undergoing cementless TKA require a longer recovery period in order to allow for the growth of new, healthy bone tissue into the prosthesis. The cementless option is rarely used on patients who are younger than 80 years of age.