The use of high viscosity bone cement material in knee replacement surgery could be the cause of tibial loosening, say researchers.

The National Center for Biotechnology Information (NCBI) looked at 13 cases of Biomet Vanguard total knee arthroplasties after patients complained of persistent pain. Each patient underwent X-rays and blood tests to determine if any infection was present, but none tested positive for infection.

Eleven of the 13 patients showed no evidence of implant loosening in x-rays, but every case was found to have a problem indicating the tibial component did not bond properly.

Each of the implants that failed to bond had been secured with high viscosity cement (HVC). No similar issues were seen in patients who had their implants secured with low or medium viscosity cement.

The researchers concluded, “In the setting of a negative infectious work-up and no radiographic evidence to suggest loosening, the surgeon should consider debonding of the tibial component as a potential cause for persistent pain if HVC cement was used with this prosthetic design.”

In another retrospective analysis, the NCBI determined that between May 2005 and December 2010, a total of 3,048 total knee replacement surgeries were performed by six surgeons. Two different knee replacement systems were used during that period of time, and nine early failures occurred in eight patients. Researchers found that high viscosity bone cement was used in each failed case.

The researchers noted that high viscosity bone cement material has been linked to micro-fractures, the generation of cement debris and early implant failure in patients who have received hip replacement surgeries.

As a result, “The mechanical properties of HVC may similarly contribute to early failure at the cement-implant interface in a small percentage of TKRs (total knee replacements),” said the researchers.

Bone Cement Material Matters

Bone cement is available in low, medium and high levels of viscosity. The higher the level, the thicker the cement.

Many surgeons have preferred to use high viscosity bone cement because they can control the substance more easily and it takes longer to harden than lower viscosity versions. The longer the surgeon can maneuver the cement, the longer the surgeon can work on that particular area.

Unfortunately, the high viscosity cement does not appear to bond as well as low or medium viscosity epoxies. High viscosity cement, or HVC, has been implicated in a number of cases of aseptic loosening, a condition in which a component of the implant comes loose for reasons not related to any infection.

One woman filed a lawsuit because she dealt with constant pain after undergoing knee replacement surgery in 2009. Her surgeon saw the tibial component had become loose, and she underwent revision surgery in 2012, she claims.

Her complaint says the high viscosity bone cement used in her first surgery had been FDA-approved through the agency’s fast-track program. She alleges the cement’s formula changed to include larger particles that caused the lack of adherence. She alleges the new formula should have been tested before it was used on patients such as herself.