Elsevier

Gait & Posture

Volume 66, October 2018, Pages 267-272
Gait & Posture

Full length article
Reliability of scapular kinematics estimated with three-dimensional motion analysis during shoulder elevation and flexion

https://doi.org/10.1016/j.gaitpost.2018.09.008Get rights and content

Highlights

  • Reliability of scapulothoracic angles during shoulder elevation & shoulder flexion.

  • Very high intra-subject reliability during shoulder elevation and shoulder flexion.

  • Shoulder elevation: inter- and intrarater reliability above 0.6 between 20–120°.

  • Shoulder flexion: inter- and intrarater reliability above 0.6 between 10–130°.

  • Humeral elevation above 120° can be critical due to soft tissue artefacts.

Abstract

Background

Knowing the reliability of three-dimensional motion analysis to evaluate scapular kinematics during upper limb movements is essential to plan further research dedicated to understanding scapulothoracic joint movements relative to the global shoulder motion.

Research question

The aim of this study was to assess the intra-subject as well as intra- and interrater reliability of scapulothoracic joint angles during shoulder elevation in scapular plane and shoulder flexion.

Methods

Twenty healthy participants (26.6 ± 3.5 years) were asked to perform maximum shoulder elevation in scapular plane as well as shoulder flexion. Reliability was assessed using the intraclass correlation coefficient (ICC) and its 95% confidence interval of scapular kinematics (rotation, tilting, pro-retraction) at each degree of global motion (shoulder elevation or shoulder flexion) between 0° to 150°.

Results

ICCs above 0.60 were accepted as good indicators for reliability. Intra-subject reliability was found to be very high (>0.9 for most part) for all scapulothoracic joint angles during both movements. Intra- and interrater reliability also showed good reliability being above 0.60 for the most part (except scapula tilting during shoulder elevation). Scapular kinematics showed low reliability during the respective first 10° and 20° of shoulder elevation and shoulder flexion. Furthermore, decreasing reliability was found above 120° of shoulder elevation or flexion.

Significance

This study generally showed good to high levels of reliability in the range of interest (20–120°) in evaluating scapula kinematics in healthy adults during shoulder elevation and flexion; these results are important for future research providing a better understanding of scapular kinematics.

Introduction

In clinical settings, upper limb range of motion is usually measured using a goniometer that does not enable the examiner to describe the motion continuously in the three planes exactly at any point in time during various movements. Furthermore, scapular kinematics during movements cannot be easily quantified clinically. The three-dimensional (3D) analysis of the shoulder movement is important since two-dimensional methods fail to account for “out-of-plane” motions, which can produce significant errors and may also fail to capture the complexity of the shoulder movement [1]. In previous studies, 3D movements of the shoulder including the glenohumeral and scapulothoracic motion have been measured using invasive methods with bone pins [[2], [3], [4]] and non-invasive methods including 3D radiographic [5], 3D marker based motion analysis [6,7] and electromagnetic-based systems [8]. Chu et al. [6], comparing scapular kinematics measured with 3D marker based motion analysis and dynamic stereo X-ray, stated that 3D marker based motion analysis is a valid method to quantify scapular kinematics while acknowledging the limitations. Several studies have reported reduced accuracy of scapular kinematics above 90° of humeral elevation with the acromion marker cluster (AMC) method [[9], [10], [11], [12]] and above 120° with skin-fixed scapular receivers [2]. Marker based 3D motion capture data can provide more detailed information on upper limb movement in children and adults. Furthermore, quantifying upper limb function allows the detection of shoulder pathologies and could possibly objectify pre- and post-treatment monitoring. Motion analysis of the upper limb has become increasingly interesting and is a rapidly growing field in movement research [[13], [14], [15], [16]].

Besides the lack of standardized descriptions of upper limb motion, results from different motion laboratories can often not be compared directly because of methodologic differences in experimental set-ups. The need for standardized protocols for upper limb motion analysis, for instance, involving the construction and use of a proper biomechanical model, has been previously emphasized [[16], [17], [18]]. Jaspers et al. [19,20] established the reliability of a measurement procedure incorporating recommendations published by the International Society of Biomechanics (ISB) defining joint coordinate systems and rotation sequences [18] for normally developing children and children with hemiplegic cerebral palsy. In normally developing children, within session intraclass correlation coefficients (ICCs) were generally high for all joint angles at the point of task achievement for different tasks, indicating good endpoint reliability; reliability between sessions was highest for scapula, shoulder and elbow kinematics. The careful selection of a set of relevant tasks was previously stated to be important for standardised upper limb protocols [17]. Most studies have analysed daily activities [15,[19], [20], [21]], which involve shoulder movements in all planes. In contrast, in clinical examinations main movements trying to restrict the shoulder kinematics to one plane (e.g. shoulder flexion in the sagittal plane) are frequently evaluated. Moreover, since disadvantages of using extracted scalers or specific points of waveforms have become apparent [22], this study aims to analyse scapular kinematics in relation to humeral elevation continuously during the movements. The reliability of using 3D motion analysis and a model based on the ISB recommendations to evaluate scapular kinematics during continuous shoulder elevation in scapular plane and shoulder flexion, however, has not yet been tested at each degree of humeral elevation. When analysing patients (e.g. with scapula dyskinesia), changes over time are often being analysed. In this context it is essential to know the reliability of scapular kinematics during continuous humeral elevation to interpret which differences might be due different assessors or measurement points and which differences or changes over time actually can be interpreted as such.

Therefore, the aim of this study was to assess the intra-subject as well as intra- and interrater reliability of scapulothoracic joint angles as measured by three-dimensional motion analysis continuously during shoulder elevation in the scapular plane and during shoulder flexion.

Section snippets

Methods

Twenty healthy subjects (13 men, 7 women) with a mean age of 26.6 years (±3.5 years) ranging from 21 to 33 years were recruited for this study. Participants were included if they were between 20 and 35 years old, and excluded if they had any shoulder problems, previous upper limb fractures, injuries, surgical procedures or muscle strains. The research ethics board of the Cantonal Hospital St. Gallen (Switzerland) approved the study, and all participants provided written informed consent prior

Results

Shoulder elevation in scapular plane as well as scapula rotation, tilting and pro-retraction angles at each degree of shoulder elevation from 0° to 150° are shown in Fig. 1. Intra-subject reliability was found to be very high (>0.90) for all scapulothoracic joint angles during shoulder elevation (Fig. 2) above 15°. Furthermore, scapula tilting and scapula pro-retraction angles show decreasing intra-subject reliability at shoulder elevations above 140°. Intra- and interrater reliability of

Discussion

The purpose of this study was to assess intra-subject as well as intra- and interrater reliability of scapular kinematics measured using 3D motion analysis in relation to humeral elevation in healthy adults. Reliability was tested during shoulder elevation in scapular plane and shoulder flexion in sagittal plane, which are tasks often used in clinical examination.

In agreement with scapulothoracic joint angles measured with bone pins [3], the current study (Figs. 1 & 3) also showed greatest

Acknowledgement

This research was supported by the Clinical Trials Unit of the Cantonal Hospital St. Gallen (CTU-Kommision Nr. 14/03).

References (33)

Cited by (6)

  • Does the examiner's experience matter in evaluation of the kinematics of the upper limb?

    2019, Journal of Biomechanics
    Citation Excerpt :

    This difficulty of the markers following real movements may reflect less precise results depending on the evaluator’s familiarity with the shoulder’s complex movements, especially those >90° (Brochard et al., 2011; Hayk et al., 2014; Janes et al., 2012). The manual placement of markers on the skin is related to palpation inaccuracies (Alexander et al., 2018) and can produce significant differences among trials, sessions, and examiners, thereby compromising the interpretation of the clinical responses observed on different days and/or by different examiners (Lucareli et al., 2016). The precision or degree of agreement between the measurements taken or observations made in different locations by different people could be clarified via the study of the reproducibility of the data and examiner experience.

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