Precision and accuracy of an electrogoniometer.
BACKGROUND
Spinal range of motion has been studied by use of a variety of different methods. One electrogoniometer has been used as a noninvasive, reliable, and accurate method. The accuracy and precision of this device has not been sufficiently documented.


OBJECTIVE
To evaluate the precision and accuracy of an electrogoniometer in comparison with two manual protractors.


METHODS
This study investigated the precision and accuracy of an electrogoniometer (OSI CA 6000).


METHODS
The precision and accuracy of the electrogoniometer were determined by a series of tests against two manual protractors. Six different movement directions were tested and 4 or 5 different angles for a given movement direction were evaluated.


RESULTS
The precision of the electrogoniometer was found to be +/- 0.1 degree for 4 different angles (10 degrees, 20 degrees, 40 degrees, and 60 degrees) in 6 different movement directions (flexion, extension, left lateral flexion, right lateral flexion, left rotation, and right rotation). The accuracy was tested by comparing both manual protractors with the electrogoniometer. Substantial disagreement for 27 of 28 datasets was found. In only one dataset was there agreement between the two manual protractors and the electrogoniometer. The mean differences were in the interval 2.0% to 11.5% between the electrogoniometer and the protractors.


CONCLUSIONS
The electrogoniometer evaluated has a very high precision when range of motion measurements are made. However, the accuracy of the device is less than acceptable.
Nordic Institute of Chiropractic & Clinical Biomechanics, Odense C, Denmark.
H W
HW
Christensen
D004568:Electrodiagnosis / Q000295:instrumentation*; D004594:Electrophysiology / Q000295:instrumentation; D004867:Equipment Design; D006801:Humans; D009068:Movement; D009983:Orthopedic Equipment; D016059:Range of Motion, Articular / Q000502:physiology*; D012680:Sensitivity and Specificity; D013131:Spine / Q000502:physiology*