Lower Extremity Functional Scale (LEFS) Calculator

How does this lower extremity functional scale (LEFS) calculator work?

This health tool evaluates the ability of the subject to perform daily activities. It comprises of a list of 20 everyday tasks and is used by clinicians as a measure of functional status and in setting goals and monitoring progress in different conditions.

LEFS addresses to patients with pain disabilities and disorders affecting one or both lower extremities and is often performed to determine the effectiveness of orthopedic interventions. A similar scale is used for upper extremity functional status.

Each of the 20 items in this lower extremity functional scale calculator has the same functional scale attached to it:

■ 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 main instruction in using the questionnaire is that the subject needs to rate any difficulties they might have on a normal day, i.e. today, in the exemplified activities, difficulties that are caused by the lower limb problem for which they are seeking attention.

The items considered are:

1. Any of usual work, housework or school activities;
2. Usual hobbies, recreational or sporting activities;
3. Getting into or out of the bath;
4. Walking between rooms;
5. Putting on your shoes or socks;
6. Squatting;
7. Lifting an object from the floor;
8. Performing light activities around home;
9. Performing heavy activities around home;
10. Getting into or out of a car;
11. Walking 2 blocks;
12. Walking a mile;
13. Going up or down 10 stairs;
14. Standing for 1 hour;
15. Sitting for 1 hour;
16. Running on even ground;
17. Running on uneven ground;
18. Making sharp turns while running fast;
19. Hopping;
20. Rolling over in bed.

As per the original study, the main objective of LEFS is to measure patient initial function, rate ongoing progress and quantify outcome. The range of lower limbs conditions the self report questionnaire addresses includes musculoskeletal disorders, hip, knee or ankle pain as well as foot injuries.

In terms of internal reliability the LEFS rates at 0.96 while test retest reliability rates are 0.86 for the general population and 0.94 for the chronic patients.

Validations studies have also been performed to compare it to the SF-36, the short form health survey from the RAND Medical Outcomes Study. The results have shown that the change detection in the lower-extremity function in LEFS has greater degrees of correlation with external prognosis compared to the physical function subscale of SF-36.

Since the lower back area and the lower extremities are anatomically and functionally related and a common symptom of patients with LBP is radiating low pain, LEFS has been used, with satisfactory psychometric results as supplementary measure of functional limitation.

The clinimetric properties of this lower extremity scale have been tested in a population of patients with ankle fracture. While for medium and long term follow up the scale was found to lack certain specificity, the responsiveness and internal consistency for short term follow up were rated high.

LEFS score interpretation

The maximum score obtainable is 80 points which signifies complete function and the lowest score is 0 which indicates very low function. All LEFS scores are then awarded as number of points out of the total of 80.

The lower the score, the higher the degree of impairment caused by the lower extremity problem. The minimal detectable change is 9 scale points meaning that for improvement or degradation to be valid, the difference between two subsequent scores needs to be equal to or higher than 9.

Some studies will then calculate the score as percentage of maximal function based on the following formula:

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

An error range of +/- 5 points is sometimes taken with the consideration that the tabulated score is within 5 points of a patient's "true" score.

References

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

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

3) Lin CW, Moseley AM, Refshauge KM, Bundy AC. (2009) The lower extremity functional scale has good clinimetric properties in people with ankle fracture. Phys Ther; 89(6):580-8.