Fontes de erro em medidas eletrogoniométricas de movimentos do joelho
Abstract
Flexible goniometers are useful for direct movement measurements. However issues
related to subject-sensor interface can introduce measurement errors. Crosstalk, i.e. the
phenomenon that flexion/extension angles affect the varus/valgus angles, and vice
versa, is considered as the main drawback of goniometers. It is not well known the
effect of the variation between identical sensors and the crosstalk due to endblocks
misalignment in frontal and transverse planes. Thus, the objective of this study was to
evaluate the effect of these sources of variation to goniometer recordings. A precision
jig, for simulating pure flexion/extension angles, was constructed. Goniometer sensors
were attached to this jig. In the initial study six biaxial goniometers were evaluated.
Each sensor showed a consistent and specific crosstalk pattern. A procedure for
correction for the inherent crosstalk, based on polynomial adjust, was proposed and
evaluated. This procedure provided a major reduction of the inherent crosstalk. A
second study was developed to evaluate the effect of endblocks misalignments. Results
showed that varus/valgus misalignments did not cause additional errors for the
recordings. Rotation between endblocks was the main source of error. Compensation
procedures developed in the first study were applied in this second one, also resulting in
crosstalk reduction. These compensations might be required in functional movement
recordings to elucidate the crosstalk effect in knee measurements and the impact of the
compensation procedures in measures, such as peaks, ranges of motion and movements
curves.