Reliability and Measurement Error of Instrument-Based Methods to Assess Ankle Evertor Strength: A Systematic Review

Vollständiger Abstract

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Context : Accurate assessment of ankle evertor strength is essential for guiding rehabilitation and return-to-sport decisions after lateral ankle sprain, yet the reliability and measurement error of commonly used assessment instruments remain unclear. Objective : To synthesize the literature evaluating the reliability and measurement error of instruments used to assess ankle evertor strength. Evidence Acquisition : A systematic search was conducted in MEDLINE, Embase, Scopus, and DiTA without date restrictions. Studies assessing voluntary instrument-measured ankle evertor strength were included and evaluated using the COSMIN risk of bias tool. Two reviewers independently screened articles and extracted data on reliability (intraclass correlation coefficient or Pearson r ) and measurement error (minimal detectable change, limit of agreement, or coefficient of variation). Sufficient reliability was defined as intraclass correlation coefficient or r ≥ .70, and sufficient measurement error was define as minimal detectable change, limit of agreement, or coefficient of variation ≤20%. Key protocol characteristics, including contraction velocity, knee position, stabilization methods, visual feedback, and verbal encouragement, were extracted. Evidence synthesis : From 4047 records, 23 studies were included. Instruments used were isokinetic dynamometers, hand-held dynamometers, vertical pulley, and custom instruments. Most participants were healthy (90%), while 10% had lateral ankle sprain. Methodological quality was rated adequate (35%), doubtful (39%), or inadequate (26%). Reliability was sufficient in 83% of extracted values, whereas measurement error was sufficient in 34%. Protocol parameters did not significantly influence test–retest reliability; however, contraction velocity, knee position, and verbal encouragement influenced test–retest measurement error, and knee position and stabilization influenced interrater reliability. Conclusion : Isokinetic dynamometry, especially in isometric testing, demonstrated the most consistent reliability and the lowest measurement error. When unavailable, hand-held dynamometers offers a reliable field alternative for isometric testing. One-repetition maximum methods may be used for dynamic strength evaluation, despite higher measurement error. Protocol parameters influencing measurement error and interrater reliability should be standardized to improve measurement reproducibility.