title: Diagnostic Accuracy of Handheld Dynamometry and 1-Repetition-Maximum Tests for Identifying Meaningful Quadriceps Strength Asymmetries.
abstract: Study Design Clinical measurement, cross-sectional. Background Quadriceps deficits are common in individuals with knee joint impairments and impact functional and quality-of-life outcomes. Quadriceps strength symmetry influences clinical decisions after knee injury. Isometric electromechanical dynamometry (ISO-ED) is the gold standard for measuring symmetry, but is not available in all clinical settings. Objectives To compare concurrent validity of handheld dynamometry and 1-repetition-maximum leg press, knee extension from 90° to 0°, and knee extension from 90° to 45° to that of ISO-ED in identifying meaningful quadriceps strength deficits. Methods Fifty-six participants with knee joint impairments completed ISO-ED and 4 alternative measures of quadriceps strength symmetry in a single session. Absolute agreement of alternative measures with ISO-ED was calculated with intraclass correlation coefficients (ICCs). Clinical agreement values at thresholds of 80% and 90% symmetry were compared between the alternatives and ISO-ED. Results Knee extension from 90° to 45° (ICC = 0.67) and handheld dynamometry (ICC = 0.70) had the greatest ICCs. Clinical agreement was also best for these measures for 80% symmetry (κ = 0.56 and 0.55, respectively) and 90% symmetry (κ = 0.19 and 0.33, respectively). Conclusion Handheld dynamometry and 1-repetition-maximum testing of knee extension from 90° to 45° are fair alternatives, although symmetry is typically overestimated. Receiver operating characteristic analysis identified alternative measure thresholds that correlated with the 80% and 90% symmetry thresholds on the ISO-ED. Clinicians should use more stringent symmetry values for these alternative tests to increase the probability that individuals have a minimum ISO-ED symmetry of 80% or 90%. J Orthop Sports Phys Ther 2017;47(2):97-107. doi:10.2519/jospt.2017.6651.
authors.forename: J Anthony
authors.initials: JA
authors.lastname: Sinacore
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Evans
authors.forename: Brittany N
authors.initials: BN
authors.lastname: Lynch
authors.forename: Richard E
authors.initials: RE
authors.lastname: Joreitz
authors.forename: James J
authors.initials: JJ
authors.lastname: Irrgang
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Lynch
mesh_terms: D000293:Adolescent; D000328:Adult; D000066491:Clinical Decision-Making; D003430:Cross-Sectional Studies; D005080:Exercise Test; D006801:Humans; D007537:Isometric Contraction; D007718:Knee Injuries / Q000175:diagnosis* / Q000503:physiopathology*; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D052097:Quadriceps Muscle / Q000503:physiopathology*; D015203:Reproducibility of Results; D055815:Young Adult
keywords: knee joint; leg extension; leg press; muscle strength dynamometer; quadriceps index