A reliable, valid and responsive questionnaire to score the impact of knee complaints on work following total knee arthroplasty: the WORQ.

The Work, Osteoarthritis or joint-Replacement Questionnaire (WORQ) was developed to assess physical difficulty experienced in work before or following total knee arthroplasty (TKA). Thirteen questions were designed. The WORQ was tested for internal consistency by factor analysis, internal reliability (Crohnbach's α), and construct validity. A test-retest reproducibility was performed for analyzing standard error of measurement (SEM agreement), reliability (ICC) and smallest detectable change (SDC) in individuals and groups. Lastly responsiveness (standardized response means [SRM]), floor and ceiling effects and interpretability (minimal important change [MIC]) were analyzed. It is shown that the WORQ is a reliable, valid and responsive questionnaire that can be used to evaluate the impact of knee complaints following TKA on patients' ability to work.