Lower Extremity Functional Scale (LEFS), introduced in 1999 by Binkley et al, is a well-established evaluation tool for measuring the activity limitations and functional outcomes of patients with a wide spectrum of lower extremity disorders of musculoskeletal origin. The LEFS is a functional status questionnaire that aims to investigate the degree of difficulty a patient experiences in performing everyday tasks, due to disorders of his/her lower extremity. The LEFS consists of 20 items, each of which is scored on a 5-point scale (0 to 4). The equivalence between the individuals’ response options and the scale points is: 0 = extreme difficulty or unable to perform activity; 1 = quite a bit of difficulty; 2 = moderate difficulty; 3 = a little bit of difficulty; 4 = no difficulty. A sub-score, termed “column total”, is derived by adding the scale points vertically. The four column totals are added horizontally to give the total LEFS score, with minimum value 0 and maximum 80.
Reliability analysis
Item analysis demonstrated that all items of the scale had good variability. LEFS-Greek internal consistency was excellent with an overall Cronbach a at 0.974. Pearson r and intraclass correlation coefficient revealed excellent correlations [0.986 and 0.986 respectively, (p<0.001)] between initial assessment and re-assessment (day-8). The paired samples t-test between the scale total score at initial assessment and re-assessment indicated no statistically significant differences (NS, p=0.658). LEFS-Greek convergent validity analysis indicated that the items were strongly related to the same construct. The Greek version of LEFS is a reliable assessment tool that can be used to measure functional ability in individuals with lower-extremity musculoskeletal disorders.
Validity measures
Factor analysis demonstrated that the scale has a single-factor structure. LEFS-Greek was strongly correlated with SF36-PF, SF36-RP and TUG test (0.93, 0.62, and -0.72, respectively; p<0.001). The questionnaire was able to distinguish between the subgroups (LEFS-Greek subgroup scores 19.70±14.43 vs. 51.03±20.39, respectively; p<0.001). In ROC analysis the area under the curve for LEFS-Greek was 0.978(95%CI 0.94-1.02, p<0.001), with cut-off points at 53, and sensitivity and specificity of 92% and 96% respectively. LEFS-Greek is a valid assessment tool that can be used to measure functional ability in individuals with lower extremity musculoskeletal disorders. This is the first study in which specific cut-off points were determined.

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