Aseptic loosening of a cemented knee implant is the most common reason a total knee arthroplasty (TKA) fails, according to the Arthroplasty Journal. Other reports indicate this failure may be occur at a rate as high as 30 percent.

Although many factors go into determining causation for aseptic loosening of a cemented knee implant, the data from some studies have underscored the possibility of a link to the use of high-viscosity bone cement.

What Exactly is Aseptic Loosening?

Aseptic loosening of a cemented knee implant is when the prosthetic used in a total knee arthroplasty starts to debond from the bone without infection being present. Since there are a good number of non-cemented prosthetics which rely upon bone in-growth of the components for adherence, aseptic loosening is not limited to cemented products.

The risk of loosening is relatively low if TKA is undertaken no sooner than 60 years of age or older. For TKA patients younger than this, the chance of failure increases dramatically, according to Cedars-Sanai Hospital. This is likely do to greater pressure on the joint from high-impact, more weight-bearing activities undertaken when a patient is younger.

Aseptic loosening tends to occur at the juncture of the tibial rather than femoral component of the knee prosthetic.

When Is A Patient Likely to Experience Aseptic Loosening?

Rarely does aseptic loosening occur immediately after surgery, but is more an issue as a prosthetic ages. Nevertheless, a knee replacement should last up to two decades and offer consistent pain-free relief. When it does not, more than likely a process known as osteolysis is involved.

What Is Osteolysis?

When the bond between a prosthetic stem and the bone begin to fail, the body is probably attempting to digest bone particles in a dynamic process known as osteolysis. According to Med India.net, osteolysis is a dissolution of bone tissue that happens when the body ceases to keep up with new bone cell production at the same rate in which it absorbs old bone cells.

Osteolysis is a pathology sometimes initiated by the presence of cobalt and chromium particulates generated by the prosthetic and process of TKA itself. The body activates its own immune system against these particulates and instigates an inflammatory response which is ultimately painful and destructive.

What Is The Role of High-Viscosity Bone Cement?

Although aseptic loosening immediately following TKA surgery is considered very rare, a report in The Knee Journal in October 2015 indicated that high-viscosity bone cement has certain traits that make it more likely to be non-adherent to the tibial trays following TKA.

Even if it doesn’t produce the immediate problem, it has also been noted that this type of cement is capable of producing a grave amount of debris through micro-fracturing. This situation then can stimulate the foreign body response of the immune system as previously indicated.