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 (TKA) 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 TKA. This study aimed to develop and validate a scale to specifically assess the level of self-management in patients after TKA.

Methods: The study was conducted in 2 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 < .01); thus, the reliability of the scale is good.

Conclusions: 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 TKA. The scale helps healthcare professionals understand the level of self-management of patients undergoing TKA.