Abstract
In 1983 we underscored the importance of understanding the cause or mechanism of failure following total knee arthroplasty. In this article we reported that revision total knee replacement was generally unsuccessful unless the surgeon new the mechanism of failure. In the ensuing years we have collectively made improvements in instrumentation, component design and material properties such that the mechanisms of failure are now different and less common than in the earlier years.
Early failure following total knee arthroplasty is generally related to technical issues. There are a myriad of such issues but many of them relate to component positioning and soft tissue balance. Post-operative wound complications are concerning as they cause an increased incidence of deep infection. Hematoma from over anticoagulation is a particular problem that leads to stiffness and increased risk for infection. Most knee systems now have multiple sizing options and instrument systems that can improve reproducibility of component implantation. Midterm failure is often due to flexion instability which has been reported in cruciate substitution and cruciate retention knees. The instability can be global, mid flexion, flexion or a combination of all 3. Issues with extension and mid flexion instability but no flexion instability are generally those with tight extensor mechanisms. Pain and stiffness are frequently due to component malalignment. One common problem is abnormal internal rotation of the tibial component.
Late failure in our institution is generally seen due to wear and loosening from earlier designs with inferior polyethylene. Late hematogenous infection occurs in people with immunocompromise, severe diabetes and diagnoses that alter the patient's ability to mount an immune response. The newest epidemic in total knee failure has been that of periprosthetic fracture. As these patients are becoming older and with worse proprioception, they are at greater risk. Generalised osteopenia and increased activity also increase the risk of fracture. Total knee arthroplasty represents a remarkable improvement in the care of the patient with knee arthritis. It is only by focusing upon and decreasing the causes of failure that we will advance use of this procedure in patient care.
