Validity, Agreement and Accuracy of A Hand-Held Dynamometer for Shoulder Muscles Strength Assessment in Healthy Individuals

Abstract

Background: The shoulder complex has a high prevalence of injuries. It is fundamental to quantify the muscle strength and identify muscular imbalances that predispose to lesions. The aim was to test concurrent validation of the muscle strength assessment with a hand held dynamometer (HHD) for shoulder joint muscles, and measure the accuracy and diagnostic agreement between instruments for assessing the strength of this joint with the hand held dynamometer and isokinetic dynamometer (ID) in a population of healthy individuals Methods: healthy individuals aged between 18 and 40 years were included. The HHD was used to test the isometric contraction of the main shoulder movements. Isometric contraction was performed for 3 seconds. Assessments with HHD and DI were performed on the same day, with a minimum interval of 90 minutes between tests. The study was approved by the Ethics Committee by report No.1537948. Concurrent validation was calculated with Pearson’s correlation, the accuracy obtained by the ROC curve and agreement by Kappa test. Results: The HHD showed concurrent validation between 0.51 – 0.83, with sensitivity between 0.90 and 0.98 and specificity between 0.64 and 0.89 for shoulder movements. The HHD demonstrated moderately-strong to excellent concurrent validity. Conclusion: These results are encouraging for the routine use of this portable and lower cost instrument in quantification of the pique torque of the shoulder muscles. Moreover, this instrument showed good accuracy and moderate to high agreement in comparison with diagnosis of the gold standard instrument.