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).
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.
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.
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.