A marker placement laser device for improving repeatability in 3D-foot motion analysis

• Marker placement in 3D Motion analysis is often associated with errors.
• A device for correct marker placement was constructed.
• The reliability for the device was excellent.
• The device can be used for marker placement on tape.

BackgroundIn 3D gait analysis, the repeated positioning of markers is associated with a high error rate, particularly when using a complex foot model with many markers. Therefore, a marker placement laser device was developed that ensures a reliable repositioning of markers. We report the development and reliability of this device for the foot at different tape conditions.MethodsIn 38 subjects, markers were placed at the foot according to the Heidelberg foot measurement method. Subjects were tested barefoot and barefoot with three different tape conditions. For all conditions, a static standing trial was captured. We analyzed differences in distances between markers and the intra-class correlation coefficients (ICC).ResultsSmall differences between the conditions (0.03–3.28 mm) and excellent ICCs (0.91–0.97 mm) were found for all parameters.ConclusionThe laser marker placement device appeared to be a reliable method to place markers on a tape at previously palpated positions and ensures an exact position. The device could find a wide application in different clinical research fields.