Introducing a knee endoprosthesis model increases risk of early revision surgery.

Background: New equipment and techniques often are used in clinical practice, occasionally without evidence of effectiveness and safety.

Questions/purposes: We asked whether the stage of introduction of an endoprosthesis model for TKA affected the risk of early revision.

Methods: We studied mandatory registry data from all centers in Finland (n = 69) that performed TKAs for primary osteoarthritis between 1998 and 2004. Of the total of 23,707 patients (28,760 TKAs), 22,551 patients (27,105 TKAs) had a followup of 5 years; we excluded longer followup from the analysis as subsequent revisions might result from wear rather than early technical failures. We used proportional hazards modeling for calculating the hazard ratios for the first 15 operations and subsequent increments of numbers of operations while adjusting for potentially confounding variables.

Results: For the first 15 operations with a new endoprosthesis, the risk was elevated (hazard ratio, 1.48; 95% confidence interval, 1.14-1.91). Absolute risk increase of early revision for the first 15 patients was 1.7% (95% confidence interval, 0.7-2.7). The risk was not increased as the numbers of TKAs incrementally performed increased.

Conclusions: Our data show an increased risk of early revision surgery for the first patients obtaining a knee endoprosthesis model previously unused in the hospital. Patients should be informed if there is a plan to introduce a new model of endoprosthesis in the hospital and offered the possibility to choose a conventional endoprosthesis instead. Although introducing potentially better endoprostheses is important, there is a need for managed introduction of new technology.

Level Of Evidence: Level I, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.