Patient Self-Management Scale after Total Knee Arthroplasty (PSMS-TKA): Instrument Development and Cross-Sectional Validation Study

Background Effective self-management after total knee arthroplasty not only improves patients' knee pain and physical function, but also improves quality of life. However, there is no assessment tool that can be targeted to evaluate the self-management level of patients after total knee arthroplasty. This study aimed to develop and validate a scale to specifically assess the level of self-management in patients after total knee arthroplasty. Methods The study was conducted in two steps: (1) instrument development; and (2) psychological tests (n = 428). For the instrument development portion, scale items were generated through a literature review and semi-structured interviews, then reviewed and revised by a panel of experts, and assessed for content validity and pilot testing. For the psychometric tests component, items were analyzed using corrected item-total scale correlations, the critical ratio method, and Cronbach's α. Construct validity was evaluated using exploratory factor analysis and validation factor analysis. Criterion correlation validity was checked by calculating Pearson's correlation coefficient using the Arthritis Self-Efficacy Scale-8 and the scale developed in this study. Internal consistency reliability was evaluated using Cronbach's α and fold-half reliability, and retest reliability was assessed using intragroup correlation coefficients. Results The Patient Self-Management Scale after Total Knee Arthroplasty (PSMS-TKA) comprises 4 factors and 23 items that assess daily behavior management, disease information management, psychosocial management, and exercise rehabilitation management. Exploratory factor analysis and validation factor analysis yielded a stable 4-factor model for the 23 items. The PSMS-TKA demonstrated good criterion-related validity when using the Arthritis Self-Efficacy-8 as a criterion. The Cronbach's α of the PSMS-TKA was 0.903, the split-half reliability was 0.934, and the test-retest reliability correlation coefficient was 0.887 (P < 0.01); thus, the reliability of the scale is good. Conclusion The PSMS-TKA developed in this study has good validity and reliability and can be used to assess the level of self-management in patients after total knee arthroplasty. The scale helps healthcare professionals understand the level of self-management of patients undergoing total knee arthroplasty.