Motion analysis is a quickly developing field, with many practical uses in research,
clinical applications and sports. The main goal of the present study was to determine
the accuracy of anatomical landmark placement in a new motion analysis method, that
uses rigid-body tracking. The position and orientation of rigid bodies were measured
by an OptiTrack (NaturalPoint, Corvallis, OR, USA) motion capture system. Eight subjects
(age: 40.8±28.8 years, mass: 69.4±18.1 kg, height: 168.1±14.8 cm) were measured by
two examiners. Intra-examiner errors were determined from the variation of the calibrated
position of anatomical landmarks, while inter-examiner errors were determined as the
difference of the mean calibrated position of anatomical landmarks between the examiners.
An intra-examiner error of just 2-3 mm was achieved in cases, the calibration method
is satisfyingly accurate. The results showed that, the error of examiner with medical
background was higher compared to the examiner with experience in the measurement
method. No connection was found between subject body mass index and calibration accuracy.
However, it was found that inter-examiner errors are very large, thus making measurements
incomparable between examiners. These findings should be considered during further
development of the measurement protocol.
