Purpose: To determine the measurement properties of a German version of the Lower Extremity Functional Scale (LEFS) in patients with hip or knee osteoarthritis undergoing total joint replacement (TJR).
Methods: This prospective cohort study included 486 consecutive patients. The LEFS and other self-reported outcome measures were administered at different time points and several classical measurement properties were determined.
Results: The German LEFS was highly reliable (ICC 0.98) and internally consistent (CA 0.95). Construct validity was proven by large to very large correlations (r = 0.52-0.91) with all other instruments in the expected directions. Factor analysis using a polychoric correlation matrix revealed two factors at baseline and 6 months explaining about 70% of the total variance. There were no floor or ceiling effects for the total score, but significant floor effects for the single items 16-19 at baseline. The LEFS was highly responsive at 6 months.
Conclusions: The German LEFS proved to be a reliable, valid and responsive tool for the self-assessment of patients undergoing total hip or knee replacement. Nevertheless, the questionnaire seems to summarize more than one construct as highlighted by the factor analysis. Further research seems therefore warranted.