Description
Videorasterstereography improves the detection of movement delays and dynamic asymmetries in the scapulothoracic kinematic of healthy subjects
BACKGROUND
In clinical practice, the assessment of scapulothoracic kinematics typically involves visually observing patients at rest and during movement. This method relies on indirect and intuitive observation of muscle activation patterns. These non-invasive methods exhibit limited inter- and intra-observer reliability. Dynamic videorasterstereography is a non-invasive, light-optical technology used to record, measure and visualise surface structures. It produces real-time images that use a curvature map to colour-code convex, concave and saddle-shaped structures on the body surface. The aim of this study was to evaluate the diagnostic efficacy of rasterstereography-assisted observation in identifying dyskinetic scapulothoracic patterns.
METHODS
This study was conducted on healthy participants with full range of motion in their shoulders. The participants performed shoulder abduction/adduction and flexion/extension cycles without any additional weight. The movements were recorded using both videorasterstereography and a conventional video camera. A metronome was used to ensure consistent timing. To model the surface of the trunk using rasterstereography, a grid of parallel light rays was projected onto the back surface and captured using indirect optical measurement techniques and corresponding optical sensors (DIERS 4Dmotion®Lab, DiCam v3.11). The mean surface curvature was then converted into a colour scale (Figures 1 and 2). Videos were evaluated for the visibility of anatomical landmarks on a Likert scale. The diagnostic performance of conventional and rasterstereography videos in detecting dyskinetic patterns, including static asymmetries, dynamic asymmetries, motion delays, and rapid compensatory movements, was compared. Two investigators independently evaluated the videos in a blinded and randomized sequence to assess intra- and inter-rater reproducibility.
RESULTS
The analysis of 118 videos (60 conventional and 58 rasterstereography) showed good-to-excellent intra-rater and inter-rater reproducibility for both techniques (ICCs 0.745 to 0.949). Similar ICCs were documented in all subgroup comparisons, with the exception of a lower inter-rater consistency was observed for the raster-augmented videos during flexion compared to that measured for videos in abduction. Videorasterstereography outperformed conventional videos in visualizing anatomical landmarks (p=0.0119) and detecting movement delays (p=0.0008) and dynamic asymmetries (p=0.0016). However, no differences were found in static asymmetry and rapid compensatory movement detection (Figure 3). Movement delays involved predominantly the scapular upward rotation and were observed most frequently at the end of the 1st third of the cycle. Rapid movements were detected with both investigation techniques throughout the scapular abduction and flexion cycles, nevertheless their frequency was four time higher in the down-going phase as in the up-going phase (Figure 4); the most frequently observed compensatory movements were rapid movements of the medial scapular border during the end of the down-going phase (Figure 5). Dyskinesis frequency (20% in the conventional and 22% in the videorasterstereography-assisted observations) matched, as expected, that of the asymptomatic population.
CONCLUSIONS
Videorasterstereography can generate a real-time dynamic model of the trunk surface, facilitating the evaluation of scapulothoracic kinematics in a straightforward manner. Its intuitive visualization upgrades optical videos of the patient’s back to "augmented reality" videos, offering additional insights into trunk surface curvature. Compared to conventional observation methods, videorasterstereography has demonstrated superior sensitivity in detecting movement delays and dynamic asymmetries during shoulder movement.. It is a reliable and promising digital technology for enhancing scapular kinematics and dyskinesis assessment in clinical and research settings, and for identifying candidates for preventive physiotherapeutic interventions.
