Discriminant Construct Validity of Hand-Held Dynamometry and Manual Muscle Testing in a Home Care Setting

Abstract

This study was conducted to investigate the discriminant construct validity of two measures of knee extension strength: hand-held dynamometry and manual muscle testing. The study employed a retrospective analysis of medical records and comparison of patient data with published reference values. The knee extension strength of 38 consecutive patients with a variety of problems requiring home based rehabilitation were measured bilaterally by hand-held dynamometry and manual muscle testing. Data were examined using analysis of variance, a Wilcoxon test, and contingency table analyses. Hand-held dynamometry was able to distinguish between the knee extension strength of patients and healthy subjects and between the stronger and weaker sides of both groups. Manual muscle testing was also able to differentiate between the strength of the stronger and weaker sides of patients. The sensitivity of manual muscle testing to differences between sides, however, was poor. The agreement between hand-held dynamometry and manual muscle testing as to the presence of a difference between sides was only fair (k=.240). If the identification of knee extension weakness relative to an external standard or a stronger side is important, hand-held dynamometry may be a better measurement procedure than manual muscle testing.