5 Reasons Why Knee Replacements Fail

Today, due to the development of new surgical techniques and treatments, the accuracy of this procedure is increased and the recovery time is decreased.

However, not all surgical procedures have the desired outcome even though knee prosthesis is built to last for decades. Sometimes, due to various reasons, the replacement fails.

Signs and Symptoms
In most of the cases, you will feel knee pain, which is the most common warning sign that something is wrong. You may also notice swelling of the knee, reduced range of motion, knee stiffness and sometimes even inability to walk.

Why do knee replacements fail?
They can fail for various reasons.

With infection at the operation site or stiffness of the knee can cause loss of ability to move the knee leading to a knee replacement failure. The surrounding soft tissue can be so weak that it can no longer provide the necessary support for the new knee, making the prosthesis fail.

An injury to the replaced knee or bone fractures can lead to failures. In rare cases, the implants can wear out or loosen over the time, even though they are built to last.

In all these cases, a second replacement surgery is necessary and a new prosthesis will be built, if possible.

Loosening Implants

It can occur in cases when the patient is obese or performs high-impact activities in excess. Sometimes, though rare, the device can fail due to the manufacturer’s faulty design. Loosening of the implant is the most common complications resulting from a faulty device.

This is more likely to occur when parts of the implant device start to separate from one another. Between the components, the soft tissue tends to grow, leading to knee pain, knee stiffness, etc.

Loosening of the knee implants is normal and it tends to occur with time. However, it does not occur for several years. In defect implants, loosening occurs within a year and sometimes within a couple of months.

Infections after Knee Replacement

One of the most serious complications following a knee replacement is infections. However, when performed by a professional and as needed, the chances of having an infection are very low.

Patients who undergo a surgical treatment for the second time, regardless of the reason, have a higher chance of getting an infection. Infections tend to develop quicker on the implanted knee as the implant does not have its own blood supply system. Thus, making it easier for microorganisms to attach to the device and infect the surrounding tissue.

In general, knee replacement infections are classified into three types:

  • Early infections – occur within the first 3 months after the surgical procedure.
  • Delayed infections – occur within 3 to 12 months after the surgical procedure.
  • Late infections – occur after 12 months, sometimes even years after the surgical procedure. These infections are mostly hematogenous, meaning that they spread from other locations in the human body. Patients who have knee prosthesis will need to take antibiotics before they undergo any surgical procedure, even dental work in order to prevent late infections of the knee implant.

OsteolysisOsteolysis is a knee replacement complication which can lead to knee replacement failure. It occurs when particles are generated by the plastic pieces of the implant. These plastic pieces then enter the patient’s immune system. The white blood cells will digest these foreign pieces, leading to a bone digestion. As a result, the bones are damaged and the implant will start to loosen, leading eventually to a knee replacement failure. Osteolysis is more common in cases where the implants are made of polyethylene.


Also known as joint stiffness is more likely to occur in obese patients or those suffering from diabetes and other chronic diseases. If after the surgery, a slow mobilization occurs, the risk for joint stiffness is higher.

Ligament Instability

This leads to knee instability and knee replacement failure. During surgery, ligaments are sometimes cut, damaged or even improperly balanced. This will make the knee skip away from one side to the other. As the ligaments heal, stability of the knee is gained. However, sometimes a knee brace might be required or even a second surgical treatment.