Lower Extremity Functional Scale (LEFS)

LEFS explained

This is a 20 item questionnaire referring to the patient’s ability to perform several daily activities, also known as functional status.

It is addressed to patients diagnosed with disorders and diseases that affect one or both lower extremities.

It serves clinicians in monitoring patients over time and in evaluating how effective certain orthopedic interventions are.

The main instruction in using the questionnaire is that the subject needs to rate any difficulties they might encounter on a normal day during the specified activities, difficulties that are linked to the lower limb problem.

The activities considered are:

Each of the 20 items in the scale are awarded a number of points varying from 0 to 4, depending on the degree of the impairment when performing the specific activity:

■ Extreme difficulty or unable to perform activity (0 points);

■ Quite a bit of difficulty (1 point);

■ Moderate difficulty (2 points);

■ A little bit of difficulty (3 points);

■ No difficulty (4 points).

The LEFS can be used to measure patient initial function, rate ongoing progress and quantify outcome in a variety of conditions, including:

■ Musculoskeletal disorders;

■ Hip pain;

■ Knee pain;

■ Ankle pain;

■ Foot injuries.

The scale was compared to the SF-36 (the short form health survey from the RAND Medical Outcomes Study) and showed greater degree of correlation with external prognosis compared to the physical function subscale of SF-36.

LEFS has also been used with satisfactory psychometric results in the functional assessment of patients with lower back pain.

A similar scale, has been devised for upper extremity functional status.

Score interpretation

The maximum score obtainable is 80 which means complete function and the lowest score is 0 which means very low and severely impaired function.

There is no specific cut-off point and the general guideline is that the higher the score, the higher the degree of impairment caused by the lower extremity problem.

The study found that the minimal detectable change is 9 scale points. This means that in order to mark a change as improvement or degradation (in subsequent evaluations), the difference between the two scores needs to be equal to or higher than 9.

An error range of +/- 5 points may be taken in consideration when the final score is within 5 points of a patient's "true" score.

In some studies, the score is used to determine a percentage of maximal function based on the following formula:

% of maximal function = (LEFS score) / 80 x 100

About the study

LEFS was created in 1999 following a study by Binkley et al. on a cohort of 107 patients diagnosed with lower-extremity musculoskeletal dysfunction.

The scale was first administered during the initial assessment, second after 24 to 48 hours from the initial assessment, and then at weekly intervals for another month.

The statistic models used were:

■ A type 2,1 intra-class correlation coefficient was used to estimate test-retest reliability;

■ Pearson correlations and one-way analyses of variance were used to examine construct validity;

■ Spearman rank-order correlation coefficients.

The LEFS reliability (α=0.96) and construct validity were supported by comparison with the SF-36.

Test-retest reliability estimates were 0.86 for the general population and 0.94 for the chronic patients.

Original source

Binkley JM, Stratford PW, Lott SA, Riddle DL. The Lower Extremity Functional Scale (LEFS): scale development, measurement properties, and clinical application. North American Orthopaedic Rehabilitation Research Network. Phys Ther. 1999; 79(4):371-83.

Other references

1. Yeung TS, Wessel J, Stratford P, Macdermid J. Reliability, validity, and responsiveness of the lower extremity functional scale for inpatients of an orthopaedic rehabilitation ward. J Orthop Sports Phys Ther. 2009; 39(6):468-77.

2. Wang YC, Hart DL, Stratford PW, Mioduski JE. Clinical interpretation of a lower-extremity functional scale-derived computerized adaptive test. Phys Ther. 2009; 89(9):957-68.

3. Dingemans SA, Kleipool SC, Mulders MA, Winkelhagen J, Schep NW, Goslings JC, Schepers T. Normative data for the lower extremity functional scale (LEFS). Acta Orthop. 2017; 28:1-5.

4. Liang HW, Hou WH, Chang KS. Application of the modified lower extremity functional scale in low back pain. Spine (Phila Pa 1976). 2013; 38(23):2043-8.