As people get older, the possibility of knee replacement surgery may grow. The pressure put on bones and joints can begin to cause mobility issues.

When a doctor identifies that these issues are affecting the patient’s quality of life, knee replacement surgery might be recommended.

Although the devices used in knee replacements are promoted as safe and very effective, the cement used in some replacement procedures might cause problems for patients post-implant, including aseptic loosening.

Bone Cement

Several types of bone cement are used in knee replacement surgery. These cements are often categorized based on their viscosity.

Low viscosity cement has a shorter working phase than other cements, meaning that it must be applied and positioned quickly. In contrast, high viscosity cement has shorter mixing phase and a longer working phase. This allows high viscosity cement to be applied slower and more precisely.

The type of cement used will mostly depend on surgeon preference, but some types of cement may have benefits while others are associated with risks. According to some claims, certain types of bone cement are more prone to cause a type of implant failure known as aseptic loosening.

What Is Aseptic Loosening?

Aseptic loosening is the failure of the bond between the bone and an implant in the absence of an infection. It’s a problematic complication experienced by some patients who undergo total knee replacement surgery.

Loosening is frequently associated with the tibial component rather than the femoral component of a total knee replacement.

Those patients who have total knee replacement surgery in their sixth decade of life have a relatively low risk of aseptic loosening. However, the risk can be greater in younger patients due to increased activity.

How Is Loosening Identified?

If a patient notices pain and disability from the implant, they should report their symptoms to their physician  – loosening may become bad enough to lead to revision surgery.

Abnormalities can include fragmentation of the cement, extensive widening of interfaces, migration of prosthetic components, and bead shedding in porous coated prostheses. This is usually visible via x-ray.

Why Do Implants Fail?

Appropriately functioning implants rely on their adherence to the bone. Fixation is often achieved by cementing the implant directly on to the bone. These implants might be tightly placed at the time of the knee replacement surgery, but may loosen over time. Friction could be generated when the joint rubs against one another in a way that creates wear and tear.

Infection can have devastating impact on a patient who has received total knee replacement surgery. Fractures and instability can also lead to problematic side effects.

Failure of the knee implant could cause the patient to have to undergo a comprehensive revision surgery.

Does High Viscosity Cement Cause Early Failure?

The Knee Journal published a bone cement report in October 2015 stating that high viscosity cement contains properties that makes it more susceptible for early failure of a knee implant. While the failure rate is generally low, the consequences can be catastrophic for the patient.

The Orthopedic Research Society (ORS) released a report in 2011 that supports this hypothesis. Scientists in the report tested stability of different types of bone cement by simulating pressure on a bone implant. The scientists monitored displacement, micromotion, and stiffness of the cements. The ORS found that the low viscosity cement exhibited the least micromotion. In contrast, high viscosity demonstrated higher stiffness and rigidity.

“Flexural and axial rigidities combined with load sharing of cement mantle may play a role in long term stability of the cemented implants,” the researchers noted. “The outcomes of the study have direct clinical relevance for the patients treated for total knee replacement surgery by reduction in revision surgeries due to aseptic loosening.”

Who Is Most Likely to Suffer from Loosening?

Certain patients are more likely to experience aseptic loosening and failure of the knee implant than others. More active and younger knee replacement patients are likely to experience bond failure due to heavy wear and tear. Activities such as jogging, aerobics and other exercises that put extreme stress on the joint could help to reduce the risk of aseptic failure. However, high viscosity cement has been reported as a common issue leading to loosening of the knee implant.

What Are Some Other Bone Cement Complications?

Bone cement is also associated with a life threatening condition called bone cement implantation syndrome. This condition, thought to be caused by toxins in the bone cement products, involves oxygen deficiency, low blood pressure, unexpected loss of consciousness, blood clots, cardiac arrest, and can even lead to death.