Research Summary

The lower extremity functional scale (LEFS): scale development, measurement properties, and clinical application

Binkley, J.M., Stratford, P.W., Lott, S.A., and Riddle, D.L. (1999). Phys. Ther. 79(4): 371–83.

Key Findings

Internally reliable

The LEFS met test-retest reliability and internal consistency measures.

Constructively Valid

LEFS scores correlated with scores from the SF-36, indicating its construct validity.

Sensitive to change over time

Prognoses by physical therapists correlated with changes to patients’ LEFS scores over time.

At the time of this study, the Lower Extremity Functional Scale (LEFS) was a newly-developed condition-specific measure distinguished by its ease of application and scoring and its potential to apply to a broad range of lower-extremity orthopaedic conditions. To determine its usefulness as a clinical and research tool, the LEFS was evaluated based on its reliability, construct validity, and sensitivity to change.

To determine its internal reliability, the LEFS was administered and readministered to patients at set intervals. Construct validity was determined by administering the SF-36, a generic measure that has served as a comparison for condition-specific measures in past studies, at certain intervals, and then checking for correlations between the two measures. To evaluate the measures’ sensitivity to change, physical therapists provided prognoses for each of the patients, which were then correlated with changes to the patients’ LEFS and SF-36 scores during a set interval.

Results indicated that the LEFS is a reliable and valid measure for a broad range of lower-extremity conditions, and is also sensitive to change to a degree that makes it an appropriate measure to implement at the individual patient level. In fact, results showed that the LEFS is better at detecting changes in lower-extremity function than the SF-36.

Relevance to Levitation

As a measure that has been deemed reliable, valid, and sensitive to change by Binkley et al. (1999), the LEFS has been used as one of the measures to evaluate the clinical efficacy of Levitation. In a retrospective pilot study, wearing Levitation for one month resulted in statistically significant improvements to physical function 1– Budarick, A.R. et al. (2020) J. Prosthet. Orthot. Under Peer Review.. These findings were based on changes in patients’ LEFS scores that passed the minimum clinically relevant threshold.

Multiple Forces Reduced

Each TCO brace model significantly reduced PF, TF, PC ligament, PT and QT forces during a deep knee bend test.

Reduced Joint Load

Each TCO brace model significantly reduced knee joint loads by at least 32% when compared to the non-braced condition.

Replicates & Extends Previous Research

Results corroborate the knee joint offloading capabilities of a TCO, as demonstrated in a previous study (Budarick et al. 2020).

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