New real-time force monitoring device with enhanced accuracy for evaluation of applied force during the joint mobilization technique

Abstract

BACKGROUND:

Force Monitoring Devices (FMDs) reported in the literature to monitor applied force during Joint Mobilization Technique (JMT) possess complex design/bulky which alters the execution of treatment, has poor accuracy and is unable to feel the resistance provided by soft tissues limits its usage in the clinical settings.

OBJECTIVES:

This study aims to develop a highly accurate, portable FMD and to demonstrate real-time monitoring of force applied by health professionals during JMT without altering its execution.

METHODS:

The FMD was constructed using the FlexiForce sensor, potential divider, ATmega 328 microcontroller, custom-written software, and liquid crystal display. The calibration, accuracy, and cyclic repeatability of the FMD were tested from 0 to 90 N applied load with a gold standard universal testing machine. For practical demonstration, the FMD was tested for monitoring applied force by a physiotherapist while performing Maitland’s grade I to IV over the 6 ${}^{\text{th}}$ cervical vertebra among 30 healthy subjects.

RESULTS:

The obtained Bland-Altman plot limits agreement for accuracy, and cyclic repeatability was $-$ 1.57 N to 1.22 N, and $-$ 1.26 N to 1.26 N, respectively with standard deviation and standard error of the mean values of 3.77% and 0.73% and 2.15% and 0.23%, respectively. The test-retest reliability of the FMD tested by the same researcher at an interval of one week showed an excellent intra-class correlation coefficient of $r=$ 1.00. The obtained force readings for grade I to IV among 30 subjects ranged from 10.33 N to 45.24 N.

CONCLUSIONS:

Appreciable performance of the developed FMD suggested that it may be useful to monitor force applied by clinicians during JMT among neck pain subjects and is a useful educational tool for academicians to teach mobilization skills.