Numerous patients in the United States have been reporting knee replacement failure from prosthetics using high viscosity bone cement, which has allegedly been causing serious complications like aseptic tibial loosening.

Knee replacement systems with bone cement are supposed to help the prosthetic attach to the bone, but certain types of bone cement have been reportedly causing serious problems for patients.

The three types of bone cement are low, medium and high viscosity. High viscosity cement is reportedly favored by surgeons because it takes less time to set and is supposed to bond sufficiently to the bone.

However, some researchers have suggested that high viscosity cement may be more likely to cause knee replacement failure because it does not bond as well to the bone compared to lower viscosity cement.

When the cement does not bond well to the knee bones, it leaves the patient vulnerable to potential complications like aseptic loosening. Aseptic loosening occurs when the implant does not bond to the bone without a related infection, with the risk reportedly being more prominent in older patients.

Aseptic loosening typically occurs when the bone cement fragments or the bond becomes broken, and more commonly occurs in the part of the implant that is attached to the tibia.

When aseptic loosening progresses to the point where patients experience pain, certain irrregularities can be seen on X-rays or other diagnostic images including:

• Progressive and extensive spacing between the bone cement, bone prosthetic, or cement prosthetic
• Fragmentation or bone cement fracture
• Migration of prosthetic components
• Bead shedding in the porous coating of the prosthetic

When spacing is noticed on radiographs, it is typically less than two millimeters wide around the tibia bone. These spaces typically develop around the bone cement interfaces in the cemented components.

Oftentimes, aseptic loosening requires patients to undergo revision surgery to resolve painful side effects including:

• Persistent and chronic pain
• Instability
• Swelling
• Decreased range of motion

Overview of High Viscosity Bone Cement and Aseptic Loosening

Several studies have been recently published indicating a correlation between aseptic loosening and high viscosity bone component. One of these studies was published in November 2018, which stated that aseptic loosening was the most common cause for failure with high viscosity bone cement knee replacement implants.

The reason for this study was to help surgeons evaluate the different bone viscosity levels. This study was performed using data reported to the American Joint Replacement Registry from 2012 to 2017, with researchers evaluated high, medium, low, and antibiotic impregnated cements in patients.

A total of 554,935 total knee replacement surgeries were reviewed, with approximately 46 percent to 61.3 percent of patients opting for high viscosity cement. Researchers ultimately found that aseptic loosening was an increased risk for patients with high viscosity bone cement.

According to another 2016 study published by the National Center for Biotechnology Information (BNBI), researchers analyzed 13 cases of knee replacement failure in which the cement of the implant had reportedly detached from the bone along the front side of the tibia.

Researchers linked these failures to high viscosity cement and found that low or medium viscosity cement reportedly did not carry the same risks.