This work lies within the multidisciplinary Southampton Musculoskeletal Research Unit (Southampton University Hospitals Trust/University of Southampton) and the Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis. The authors wish to thank their funding sources; Arthritis Research UK for funding of laboratory equipment (Grant No: 18512) and Vicon Motion System, Oxford UK for providing funding for a PhD studentship (M.Warner). The authors also wish to thank the participants, and Kate Scott and Lindsay Pringle for their help with participant recruitment.

NOTE: The use of human participants was approved by the Faculty of Health Sciences Ethics Committee at the University of Southampton. All participants signed consent forms before data collection commenced. For the data presented in this study kinematics were recorded using a passive marker motion capture system consisting of 12 cameras; six 4-megapixel cameras and six 16-megapixel cameras operating at sampling frequency of 120 Hz.
1. Participant Preparation
<ol>
	<li>Ask subjects to remove t...

<ol>
	<li>Kibler, W. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+implications+of+scapular+dyskinesis+in+shoulder+injury:+the+2013+consensus+statement+from+the+'scapular+summit'.">Clinical implications of scapular dyskinesis in shoulder injury: the 2013 consensus statement from the 'scapular summit'.</a> British Journal of Sports Medicine. 47, 877-885 (2013).</li><li>Luckasiewicz, A. C., McClure, P. W., Michener, L. 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W., Bialker, J., Neff, N., Williams, G., Karduna, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shoulder+function+and+3-dimensional+kinematics+in+people+with+shoulder+impingement+syndrome+before+and+after+a+6-week+exercise+program.">Shoulder function and 3-dimensional kinematics in people with shoulder impingement syndrome before and after a 6-week exercise program.</a> Physical Therapy. 84, 832-848 (2004).</li><li>Lin, J. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+activity+characteristics+of+individuals+with+shoulder+dysfunctions.">Functional activity characteristics of individuals with shoulder dysfunctions.</a> Journal of Electromyography and Kinesiology. 15, 576-586 (2005).</li><li>Tate, A. R., McClure, P. W., Kareha, S., Irwin, D., Barbe, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+clinical+method+for+identifying+scapular+dykinesis,+Part+2:+Validity.">A clinical method for identifying scapular dykinesis, Part 2: Validity.</a> Journal of Athletic Training. 44, 165-173 (2009).</li><li>Timmons, M. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scapular+kinematics+and+subacromial-impingement+syndrome:+a+meta-analysis.">Scapular kinematics and subacromial-impingement syndrome: a meta-analysis.</a> Journal of Sports Rehabilitation. 21, 354-370 (2012).</li><li>Endo, K. Y. 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A roentgenographic study.</a> Journal of Bone and Joint Surgery (Am). 48, 1503-1510 (1966).</li><li>Poppen, N. K., Walker, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Normal+and+abnormal+motion+of+the+shoulder.">Normal and abnormal motion of the shoulder.</a> Journal of Bone and Joint Surgery (Am). 58, 195-201 (1976).</li><li>Graichen, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+resonance-based+motion+analysis+of+the+shoulder+during+elevation).">Magnetic resonance-based motion analysis of the shoulder during elevation).</a> Clinical Orthopedic Related Research. 370, 154-163 (2000).</li><li>Youdas, J. W., Carey, J. R., Garrett, T. R., Suman, V. 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P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+scapular+local+coordinate+systems.">Comparison of scapular local coordinate systems.</a> Clinical Biomechanics. 25, 415-421 (2010).</li><li>Ludewig, P. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Motion+of+the+shoulder+complex+during+multiplanar+humeral+elevation.">Motion of the shoulder complex during multiplanar humeral elevation.</a> The Journal of Bone and Joint Surgery. 91, 378-389 (2009).</li><li>Johnson, G. R., Stuart, P. 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None of the authors had any affiliation with any organization that could influence the outcome of this work.

The choice of methodology for determining scapular kinematics is crucial, and consideration of the validity, reliability and its appropriateness for the research study should be given. Various methods have been adopted throughout the literature but each method has its limitations. The acromion marker cluster overcomes a number of these limitations, such as projection errors from 2D imaging or requiring repeated interpretation of the location of the scapula by providing non-invasive dynamic kinematic measurement of the sc...

Objective, quantitative measurement of scapular kinematics can provide an assessment of abnormal movement patterns associated with shoulder dysfunction1, such as reduced upward rotation and posterior tilt during arm elevation observed in shoulder impingement2-8. Measurement of scapular kinematics, however, is difficult due to the bone&#8217;s deep position and gliding nature beneath the skin surface1. Typical kinematic measurement techniques of attaching reflective markers over anatomical landmarks do not adequately track the scapula as it glides beneath the skin surface9. Various methods have been adopted throughout the literature to overcome these difficulties, including; imaging (X-ray or magnetic resonance)10-14, goniometers15,16, bone pins17-22, manual palpation23,24, and the acromion method3,5,19,25. Each method, however, has its limitations which include: exposure to radiation, projection errors in the case of two-dimensional image based analysis, require repeated subjective interpretation of the location of the scapula, are static in nature or are highly invasive (e.g. bone pins).
A solution to overcome some of these difficulties is to employ the acromion method where an electromagnetic sensor is attached to the flat portion of the acromion25, a flat portion of bone which extends anteriorly at the most lateral part of the scapula leading from the spine of the scapula. The principle idea behind using the acromion method is to reduce skin movement artifact, as the acromion has been shown to have the least amount of skin movement artifact compared to other sites on the scapula26. The acromion method is non-invasive and provides dynamic three-dimensional measurement of scapular kinematics. Validation studies have shown the acromion method to be valid up to 120&#176; during the arm elevation phase when using electromagnetic sensors17,27. When using marker based motion capture devices a series of markers arranged in a cluster, the acromion marker cluster (AMC), is required and has been shown to be valid when using an active-marker motion capture system28 and whilst using a passive-marker motion capture system during arm elevation and arm lowering29.
The use of the AMC with a passive marker motion capture device for measuring scapular kinematics has been used to assess changes in scapular kinematics following an intervention to address shoulder impingement30. The valid use of this method, however, depends on the ability to accurately apply the cluster of markers, the position of which has been shown to affect results31, calibrate anatomical landmarks32 and ensuring arm movements are within a valid range of motion (i.e. below 120&#176; arm elevation)29. It has also been suggested the reapplication of the marker cluster, when using an active marker based motion capture system, was found to be the source of increased error for scapular posterior tilt28. It is, therefore, important to establish the between-day reliability of the acromion method to ensure it provides a stable measure of scapular kinematics. Ensuring that measurements are reliable will enable changes in scapular kinematics, due to an intervention, for example, to be measured and examined. The methods used to measure scapular kinematics have been described elsewhere29,33; the aim of the present study was to provide a step-by-step guide and reference tool for applying these methods using a passive-marker motion capture system, with consideration to the potential sources of error, and to examine the reliability of the measurement method.

<table border="0" cellpadding="0" cellspacing="0" width="583">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Name of Material/ Equipment</td>
			<td style="width:81px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Passive marker capture system</td>
			<td style="width:81px;">Vicon Motion Systems</td>
			<td style="width:119px;">N/A</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Nexus</td>
			<td style="width:81px;">Vicon Motion Systems</td>
			<td style="width:119px;">N/A</td>
			<td>Data capture software</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Bodybuilder</td>
			<td style="width:81px;">Vicon Motion Systems</td>
			<td style="width:119px;">N/A</td>
			<td>Modeling software</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">14 mm retro reflective markers</td>
			<td style="width:81px;">Vicon Motion Systems</td>
			<td style="width:119px;">VACC-V162B</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">6.5mm retro reflective markers</td>
			<td style="width:81px;">Vicon Motion Systems</td>
			<td style="width:119px;">VACC-V166</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Calibration wand</td>
			<td style="width:81px;">Vicon Motion Systems</td>
			<td style="width:119px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Plastic base</td>
			<td style="width:81px;">N/A</td>
			<td style="width:119px;">N/A</td>
			<td>Constructed &#39;in-house&#39;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Matlab</td>
			<td style="width:81px;">Mathworks</td>
			<td style="width:119px;">N/A</td>
			<td>Numerical modelling software</td>
		</tr>
	</tbody>
</table>

measurement of dynamic scapular kinematics using an acromion marker cluster to minimize skin movement artifact

The measurement of dynamic scapular kinematics is complex due to the sliding nature of the scapula beneath the skin surface. The aim of the study was to clearly describe the acromion marker cluster (AMC) method of determining scapular kinematics when using a passive marker motion capture system, with consideration for the sources of error which could affect the validity and reliability of measurements. The AMC method involves placing a cluster of markers over the posterior acromion, and through calibration of anatomical landmarks with respect to the marker cluster it is possible to obtain valid measurements of scapular kinematics. The reliability of the method was examined between two days in a group of 15 healthy individuals (aged 19-38 years, eight males) as they performed arm elevation, to 120&#176;, and lowering in the frontal, scapular and sagittal planes. Results showed that between-day reliability was good for upward scapular rotation (Coefficient of Multiple Correlation; CMC = 0.92) and posterior tilt (CMC = 0.70) but fair for internal rotation (CMC = 0.53) during the arm elevation phase. The waveform error was lower for upward rotation (2.7&#176; to 4.4&#176;) and posterior tilt (1.3&#176; to 2.8&#176;), compared to internal rotation (5.4&#176; to 7.3&#176;). The reliability during the lowering phase was comparable to results observed during the elevation phase. If the protocol outlined in this study is adhered to, the AMC provides a reliable measurement of upward rotation and posterior tilt during the elevation and lowering phases of arm movement.

Fifteen participants who had no known history of shoulder, neck or arm injuries were recruited onto the study (Table 2). To assess intra-rater (between-day) reliability, participants attended two data collection sessions separated by at least 24 hours and a maximum of 7 days. During each data collection session, the same investigator performed the protocol for attaching reflective markers, the acromion marker cluster and anatomical landmark calibrations, as detailed above. The reliability of the kinemati...

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Measurement of Dynamic Scapular Kinematics Using an Acromion Marker Cluster to Minimize Skin Movement Artifact

This report presents details of how to adopt the acromion marker cluster method of obtaining scapular kinematics when using a passive marker motion capture device. As has been described in the literature, this method provides a robust, non-invasive, three-dimensional, dynamic and valid measurement of scapular kinematics, minimizing skin movement artifact.

The measurement of dynamic scapular kinematics is complex due to the sliding nature of the scapula beneath the skin surface. The aim of the study was to ...

measurement-dynamic-scapular-kinematics-using-an-acromion-marker

Research

JoVE Journal

Medicine

19.0K Görüntüleme.  University of Southampton.  Bu rapor bir pasif işaretleyici hareket yakalama cihazı kullanırken skapular kinematiği elde akromion işaretleyici küme yöntemi benimsemeye nasıl ayrıntılarını sunar. Literatürde açıklandığı gibi, bu yöntem, cilt hareket artefaktı en aza indirerek, skapula kinematik bir invazif olmayan, sağlam üç-boyutlu, dinamik ve geçerli bir ölçüm sağlar. 