Is the instrumented-pointer method of calibrating anatomical landmarks in 3D motion analysis reliable?. (28th February 2017)

• Record Type: Journal Article
• Authors: Tawy, Gwenllian Fflur; Rowe, Philip
• Is Part Of: Journal of biomechanics. Volume 53(2017)
• Page Start: 205
• Page End: 209
• Publication Date: 2017-02-28
• Subjects: Motion analysis -- Anatomical landmark calibration -- Subject calibration -- Protocol reliability -- instrumented-pointer; Animal mechanics -- Periodicals; Biomechanics -- Periodicals; Biomechanics -- Periodicals; Mécanique animale -- Périodiques; Biomécanique -- Périodiques; Electronic journals; 571.4305
• DOI: 10.1016/j.jbiomech.2017.01.019
• Languages: English
• ISSNs: 0021-9290

Abstract

Abstract: Instrumented-pointers are often used to calibrate anatomical landmarks in biomechanical analyses. However, little is known about the effect of altering the orientation of the pointer during calibration on the co-ordinates recorded. Incorrect positioning of a landmark influences the axes created, and thus the kinematic data recorded. This study aimed to investigate the reliability of the pointer method for anatomical calibration. Two points were drawn onto a fixed box to resemble knee joint epicondyles, then a custom-made pointer was used to define the positions of these landmarks in three-dimensions. Twenty different pointer-orientations were chosen, and the position of the pointer in each of these orientations was recorded 8 times. Euclidean distances between single points were calculated for both landmarks and compared statistically ( α = 0.05). Average Euclidean distances between all reconstructed points were 3.2±1.4 mm (range: 0.3–7.1 mm) for one landmark and 3.3±1.5 mm (range: 0.3–7.9mm) for the other. The x - and y -co-ordinates recorded differed statistically when the pointer was moved about the X and Y axes (anterior/posterior and superior/inferior to landmark) ( p < 0.05). No statistical differences were found between co-ordinates recorded when the pointer was moved around the Z axes ( p > 0.05). ICC values for all co-ordinates were excellent, highlighting the reliability of the method (ICC > 0.90). These results support this method of anatomical calibration; however, we recommend that pointers be consistently held in a neutral oriented position (where the handle is not anterior, posterior, superior or inferior to the landmark) during calibration, to reduce the likelihood of calibration errors.