Development and Underlying Structure of a Second-Generation Appropriateness Classification System for Total Knee Arthroplasty

Objective. Evidence supports the validity of total knee arthroplasty (TKA) appropriateness classification based on the RAND Corporation and University of California Los Angeles system. The system, however, is similar to 2 decades old, and the science and clinical application of TKA has changed dramatically. We undertook this study to describe the methods used to develop a second-generation system and to examine the structure of the system to determine the extent to which each of the indication criteria informed appropriateness. Methods. Multivariable multinomial regression analyses determined the extent to which each of the 8 individually analyzed indication criteria informed appropriateness judgments. Classification tree analysis illustrates how the indication criteria, in combination, led to judgments of appropriate, inappropriate, or uncertain. Results. An expert panel selected 8 indication criteria (i.e., age, knee pain, function, radiographic osteoarthritis severity, osteoarthritis location, psychological factors, pain catastrophizing, and comorbidities). A total of 1,008 clinical scenarios were written, based on the criteria. Regression analyses indicated that age, knee pain, function, and radiographic severity dominated prediction of appropriateness, while the other criteria played a smaller role. Classification tree analysis confirmed the regression findings. Conclusion. Our second-generation classification system, which incorporates contemporary indicators of TKA prognosis and risk, demonstrated preliminary evidence for utility in clinical practice.