Reliability and validity of measuring grip strength with a robotic-assisted device in patients after stroke

Abstract

Background/Aims Robotic assisted devices are increasingly used in neurological rehabilitation for improving upper extremity function. The new hand therapy device Manovo Power of the Armeo Power provides integrated assessment of grip strength measurement. Reliability and validity of the grip strength measurement are unknown. The aim of this study was to evaluate the reliability and validity of grip strength measurement with the hand module of the Manovo Power robot-assisted device compared with a Biometrics E-Link hand-grip dynamometer. Methods This was a cross-sectional study design with grip strength measurements taken once a day for a total of 3 days, with a 2-day interval in between each test. Participants of the study were patients <24 months after first stroke with reduced hand function (n=51). Relative reliability was evaluated using intraclass correlation coefficients (ICC) (2,1). Satisfactory reliability was defined as an ICC>0.8. Absolute reliability was evaluated using limits of agreement (LoA). Validity was supported if the correlation between measures with the two devices was >0.6. Results The robotic device had good intra-rater reliability (ICC=0.89, 95% confidence interval [CI] 0.81–0.94, LoA 1.23–1.16) and inter-rater reliability (ICC=0.91, 95% CI 0.85–0.95, LoA 1.01–1.23). Intra-rater reliability of the Biometrics E-Link grip strength dynamometer was higher compared with the robotic device (ICC=0.98, 95% CI 0.96–0.99, LoA 3.94–4.42). Validity was confirmed by a correlation between devices of 0.76 (95% CI 0.60–0.85). Conclusions Measurement of grip strength with the robotic device was reliable and valid in patients with stroke and impaired hand function. There was no absolute measurement error that might have indicated a learning effect. Reliability was higher for the Biometrics E-Link grip strength dynamometer compared with the robotic-assisted device. Using the robotic device for grip strength measurement in patients who exercise with that device saves time and increases efficiency.