Comparative assessment of knee extensor and flexor muscle strength measured using a hand-held vs. isokinetic dynamometer.
Guillaume Muff, Stéphane Dufour, Alain Meyer and 5 others
PMID 27799667WHAT IT FOUND
Hand-held dynamometer knee strength readings were repeatable and tracked closely with isokinetic readings in healthy adults.
Hand-held flexor/extensor ratios did not match isokinetic ratios well.
Key findings
01Hand-held dynamometer strength values correlated with isokinetic values from r=0.72 to r=0.87 (p<0.01).
02Three repeated hand-held measurements were consistent, with coefficients of variation from 3.2% to 4.2%.
03Hand-held flexor/extensor ratios correlated with isokinetic ratios for concentric 180°/sec and isometric 0°/sec on both sides, for concentric 60°/sec only on the non-dominant side, and not for eccentric testing.
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How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only healthy, relatively young volunteers without knee or neuromuscular disease, so it does not show that hand-held dynamometer readings agree with isokinetic readings in patients with knee pain, injury, or weakness. All measurements were done by one experienced examiner, and the paper notes that examiner strength may matter, so results may not transfer to less experienced or differently built clinicians. The two devices used different units (Nm and kgf), so the study could compare how values moved together but not establish direct agreement in absolute strength. No patients were tested and no clinical outcomes were measured, so this paper cannot show that using a hand-held dynamometer improves diagnosis, treatment decisions, or patient function.
Declared interests
No funding or conflict-of-interest statement is reported in the supplied article text.
The easy way to misread this
Do not conclude that a hand-held dynamometer can replace isokinetic testing for knee flexor/extensor ratios. The study found strength-value correlations, but the ratio correlations were not strong and no correlation was seen for eccentric ratios.