Brief report Reliability and accuracy of different sensors of a flexible electrogoniometer Angela Shiratsu, H.J.C.G. Coury * Department of Physical Therapy, Federal University of S~ ao Carlos, Rodovia Washington Luis, Km 235, CP, 676, 13565-905 S~ ao Carlos, SP, Brazil Received 21 February 2003; accepted 30 April 2003 Abstract Objective. To describe a gauging device for electrogoniometer sensors and to evaluate the reliability and accuracy of different sensors including two similar sensors. Design. Repeated measurement design for reliability. Background. Despite being considered reliable equipment, several aspects of electrogoniometer reliability and accuracy have not been reported so far. Method. Five repeated measurements of each electrogoniometer sensor were performed in 1° increments, during the whole uniplanar amplitudes of flexion, extension, lateral deviations and rotational movements, totaling 6380 measurements. Results. Values from the coefficient of variation and mean square error, respectively indicated that the reliability and accuracy of the sensors varied between sensors and movements, with goniometers being more reliable and accurate than torsiometers. A sig- nificant difference between identical sensors was identified. Conclusions. No similar pattern of variation was found between the sensors evaluated, indicating that every sensor should be tested for its reliability and accuracy when highly precise measurements are needed, and particularly when bilateral limbs are being compared. Relevance Research on movement recordings demands precise methodology for quantifying angular variations. Ó 2003 Elsevier Ltd. All rights reserved. Keywords: Electrogoniometer; Reliability; Accuracy 1. Introduction Flexible electrogoniometers are presented commer- cially in different sizes, as they are anthropometric de- pendent. Some types of electrogoniometer (EGM), such as the models for wrist movements, have been used for the study of diverse functional situations (Hansson et al., 1996; Gil Coury et al., 2000), and are recognized as re- liable and accurate in the evaluation of uniplanar movements (Rawes et al., 1996). However, little infor- mation is available on the reliability and accuracy of back electrogoniometers. Moreover, no comparative evaluation of identical sensors is available in the literature. Therefore, the ob- jectives of this study were: to describe a device for gauging the flexible electrogoniometer; to evaluate the reliability and accuracy of four different types of sensor using the gauging device as reference and; to compare measurements from two similar types of sensor. 2. Methods 2.1. Equipments A Biometrics electrogoniometer (Biometrics, Cwmf- elinfach, Gwent, UK) and the device for gauging the flexible electrogoniometer (Gauging Device), designed for this study, were used. Electrogoniometer. The Biometrics electrogoniometer used included an angle display unit (ADU 301), with different twin axis back goniometers: XM180B (12 cm spring length); XM150B––I and II (about 10 cm spring * Corresponding author. E-mail address: helenice@power.ufscar.br (H.J.C.G. Coury). 0268-0033/03/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0268-0033(03)00110-4 www.elsevier.com/locate/clinbiomech Clinical Biomechanics 18 (2003) 682–684