Comparison between tripod and skin-fixed recording of scapular motion

Carel G.M. Meskers*, Michiel A.J. van de Sande, Jurriaan H. de Groot

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Non-invasive dynamical measurements of 3D scapular motion can be performed easily by attachment of a 6 DOF electromagnetic receiver onto the skin above the acromion. To quantify the introduction of possible errors due to skin displacement, we assessed 3D scapular positions on n = 8 subjects by both tripod and skin-fixed method. Error analysis included the variables method (tripod, skin-fixed simultaneously with tripod, separate skin-fixed at 0 and 0.25 Hz of elevation speed), plane of elevation (0° and 90°) and observation (receiver replacement: n = 3). Inter-individual 'group' differences depended on elevation plane and showed an average underestimation of scapular rotation of 6.5° (worst case 13°) using the skin-fixed method. Only the group RMSE, not the individual RMSE, could be successfully lowered using linear regression (to about 2°). Inter-trial reliability (RMSE <3.24°, ICC>0.94) and RMSE between 0 and 0.25 Hz recordings (about 2.5°) were satisfactory. Intra-observer RMSE after replacement of the skin-fixed receiver was 5°. The skin-fixed method is suitable for dynamic recordings of scapular rotations; however, measurements are precise only when the acromion receiver is not replaced. Combined with a relatively low accuracy, we conclude that the skin-fixed method should be used only in combination with tripod 'calibration'.

Original languageEnglish
Pages (from-to)941-946
Number of pages6
JournalJournal of Biomechanics
Volume40
Issue number4
DOIs
Publication statusPublished - 23 Feb 2007

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