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Simplified Measurement of Maximum Strength After Knee Surgery: Application-Based Knee-Training Device Compared to Isokinetic Testing

Authors Horstmann H, Medico P, Lasch F, Krutsch W, Weber-Spickschen TS

Received 6 May 2019

Accepted for publication 31 October 2019

Published 22 January 2020 Volume 2020:11 Pages 43—49


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 2

Editor who approved publication: Prof. Dr. Andreas Imhoff

Hauke Horstmann, 1 Pascal Medico, 2 Florian Lasch, 3 Werner Krutsch, 4 Thomas Sanjay Weber-Spickschen 2

1Department of Orthopaedic Surgery, Hannover Medical School, Hannover 30625, Germany; 2Institute of Sports Medicine, Hannover Medical School, Hannover 30625, Germany; 3Institute for Biometry, Hannover Medical School, Hannover 30625, Germany; 4Trauma Department, University of Regensburg, Regensburg 93053, Germany

Correspondence: Hauke Horstmann
Diakovere – Annastift, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Street 1-7, Hannover 30625, Germany
Tel +49 5115354568

Context: Isokinetic testing is used as a standard tool in measuring strength in professional athletes. It is often used to evaluate improvement during rehabilitation. The disadvantages of isokinetic testing include its costs, the fact that it is not portable, and its risk of injury, which makes it not suitable for early postoperative rehabilitation.
Hypothesis: The aim of this study was to investigate the relationship between the results of the isokinetic testing and the measurements of an application-based knee-training device.
Study Design: Exploratory diagnostic study.
Methods: In this monocentric study, 100 subjects performed an isokinetic maximum strength examination and an assessment on the application-based knee-training device in a randomized order. The isokinetic testing was based on the Swiss Olympic protocol with 3 sets of 5 repetitions of maximum strength testing for flexion and extension. The subjects consisted of 50 healthy professional athletes and 50 healthy recreational athletes, half male and half female, between the ages of 18 to 30 years old.
Results: No medical or technical issues were reported. The analysis of the relationship between application-based knee-training device and extension showed a Pearson correlation coefficient of r=0.667 for the left knee and r=0.604 for the right knee. For flexion, the Pearson correlation coefficient was r=0.640 for the left side and r=0.673 for the right side. When strength measured by the application-based knee-training device was adjusted for height and weight of the subjects, the Pearson correlation was even stronger (extension left: r=0.727, right: r=0.689; flexion left: r=0.641, right: r=0.711).
Conclusion: The study shows a moderate to high correlation between isokinetic testing and the application-based knee-training device. These results suggest that the application-based knee-training device is effective for early strength rehabilitation without the risk of injury.

Keywords: knee, isokinetic, app-based rehabilitation, exergame

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