A Validity and Reliability Study of the K-Muscle Controller Hand-Held Dynamometer in Measuring Shoulder's Internal...

Area of Science:

• Orthopedics
• Rehabilitation Medicine
• Biomedical Engineering

Background:

• Shoulder impingement syndrome (SIS) often requires accurate strength measurement for diagnosis and treatment.
• Existing dynamometers may have limitations in portability or ease of use.
• Validating new handheld devices is crucial for clinical practice.

Purpose of the Study:

• To assess the validity and reliability of the K-Muscle Controller, a new handheld dynamometer.
• To compare its measurements of shoulder external and internal rotation strength against the MicroFET2 device.
• To evaluate its utility in patients diagnosed with shoulder impingement syndrome (SIS).

Main Methods:

• Two groups of SIS patients (n=22 and n=25) participated.
• Isometric shoulder rotation strength was measured using the K-Muscle Controller and/or MicroFET2.
• Intra-Class Correlation (ICC), Coefficient of Variation (CoV), and Bland-Altman plots were used for analysis.

Main Results:

• High ICC values (0.944–0.986) indicated excellent reliability and validity for the K-Muscle Controller.
• CoV values ranged from 31.77% to 48.57%.
• Bland-Altman plots confirmed strong agreement between measurements without systematic bias.

Conclusions:

• The K-Muscle Controller is a reliable tool for measuring shoulder external and internal rotation strength.
• Its performance is comparable to established devices like the MicroFET2.
• This device shows promise for clinical use in assessing shoulder strength in both healthy and pathological conditions.