When do total knee replacements fail?

Background: A recent study has provided evidence-based guidelines for the follow-up of cemented total hip arthroplasty. As yet, there are no such guidelines on the surveillance of total knee arthroplasty. We reviewed the outcomes of patients who underwent this procedure in 1998 and 1999 at our institution.

Methods: All patients were identified from operating theater log books. The follow-up data was then retrieved from the electronic patient record system used at our institution. We recorded the age, sex, side of procedure, evidence of radiological loosening, and date of revision surgery. The data with regards to radiological evidence of loosening and revision surgery were then analyzed using a R statistical software package. From this we were able to plot Kaplan-Meier survival and hazard plots.

Results: We identified 296 primary total knee arthroplasties. Using radiological evidence of loosening as the end point, we found that there was a gradual increase in failure with a peak at 8 years (Fig. 1). There was a 10-year survival rate of 85.8%. Using revision surgery, for any cause, as the end point, we found that again there was a constant rate increase up to a peak at 8 years (Figs. 2 and 3). There was a 10-year survival rate of 91.5%.

Conclusions: Once the patient has made it through the first postoperative year, they do not need to be followed up again until 8 years, assuming they remain asymptomatic.

Level Of Evidence: Therapeutic Level IV.