RESEARCH REPORT PLATFORM PRESENTATION

CONTROLLING MANUALLY APPLIED FORCES IN MANUAL THERAPY TECHNIQUES. Waddington G¹, Adams R²; ¹University of Canberra. ²University of Sydney

PURPOSE: To control force applied in manual therapy an experimental version of a mobilizing device incorporating a dynamometer. RELEVANCE: In both simulation and manual therapy studies, substantial variability has been shown when therapists attempt to replicate an applied force. Knowledge about the forces employed during treatment could reduce this variability and improve both reliability and clinical safety. PARTICIPANTS: Thirty physiotherapists were recruited from two major teaching hospitals in the Canberra Australia region. METHODS: Therapists used the device to apply applied a randomised sequence of the standard grade I, II, III or IV mobilisation forces to a plinth surface. The dial was obscured and the therapists were using their concept of the force appropriate for each grade to guide force production with no feedback. Comfort ratings of grade III force applied by hand and a 100N force applied with the device dial visible were also obtained. After each condition the therapist was asked to rate their comfort during the performance of the PA pressure on a 100mm visual analogue scale. ANALYSIS: Reliability: The ICC(2,1) reliability index was calculated for manual force production without feed back and whenusing the dial readout of the dynamometer to control force application. To compare variance in concept-guided and device-guided forces, F-ratios were formed using the variance between the mean forces generated over three attempts by thirty physiotherapists in the numerator, and the variance over 10 repetitions of visually guided force application on a set of digital scales in the denominator. Scores for hand comfort during a PA force application using the mobilisation dynamometer or the therapist’s hands alone were compared with a repeated measures ANOVA. RESULTS: The ICC(2,1) was found to be 0.63 (95% CI = 0.36-0.93) for manual force production without feed back on occasions. When three forces (50, 100 and 200 N) were applied ten times to digital scales, using the dial readout of the dynamometer to control force application, the ICC (2,1) was 0.999 (95% CI 0.996-0.9999). Relative variance in force production values was significant with all p values <0.001. The mean (sd) scores for hand comfort during a PA force application using the mobilisation dynamometer or the therapist’s hands alone were 8.3 (0.8) and 5 (2.0) respectively. Comfort ratings were higher when using the device than when using the pisiform grip [F(1,29) = 86.1, p < 0.01]. CONCLUSIONS: Forces produced by different physiotherapists trying to push at the same grade varied, and to a significantly greater extent than force productions made with the same device but guided by the use of the dynamometer dial readout. The device was found to be significantly more comfortable to use than the hands in the pisiform grip. IMPLICATIONS: Physiotherapy mobilization techniques require the application of specified forces, quantification of these forces, to determine the amount of force corresponding to pain onset (for reference in future treatment sessions), and to allow inter-therapist treatment comparisons, has previously only been possible with instrumented plinths. Development of a device that improves therapist feedback regarding force and improves therapist comfort in a clinical environment may lead to improved patient outcomes. KEYWORDS: Manual therapy, dynamometer, force variability. FUNDING ACKNOWLEDGEMENTS: Nil. CONTACT: gordon.waddington@canberra.edu.au

ETHICS COMMITTEE: University of Sydney Ethics Committee