Maintenance of a vertically aligned posture of the head and trunk in sitting is a fundamental skill that demonstrates the presence of neuromotor control. Clinical assessments of posture are generally subjective. Studies have quantified posture using different technologies, but the application of such technologies in a clinical environment remains difficult. Video recordings, however, are easily used clinically and have potential for quantitative analysis of movement. This study used a video-based method to generate a numerical measure of postural alignment of the head and trunk in sitting. Static and dynamic trials of 12 healthy seated adults were simultaneously recorded with a sagittal video camera and a 3D motion capture system. Segmental angles were calculated for the Head, Neck and six Trunk segments. An agreed definition of aligned static sitting posture agreed was used by five clinically experienced experts to identify video frames where the participants' posture was aligned. The five subsets of frames that defined the aligned posture were combined to give aligned segments (mean±SD) for each participant. Agreement between experts in the definition (mean) of aligned segmental angles was excellent (ICC=0.99) and intra-assessor reliability (SD) lay within 2.1°-11.6°. Agreement between the video-based method and the 3D system was below 3.8° and 8.4° for static and dynamic trials respectively. This video-based method allowed the quantification of sitting posture and provided greater detail of the trunk/spinal profile than previous methods. It has potential as a complementary tool, alongside subjective assessments, for patients with a wide variety of pathologies.

Highlights  This study developed an objective measure of head/trunk control in children with CP  Simplified objective rules of an existing clinical test (SATCo) were generated  These objective rules successfully mirrored the subjective assessment  The SATCo is supported and validated by objective correlates  The results give support to future full automation of trunk control measurement

Full trunk control in sitting is demonstrated only when the head-trunk are aligned and upper limbs remain free of contact from mechanical support. These components represent a Controlled Kinetic Chain and can be evaluated in people with neuromotor disability using the Segmental Assessment of Trunk Control (SATCo) when a therapist provides manual trunk support at different segmental levels. However, the SATCo, as with other clinical assessments of control, is subjective. The SATCo was translated to objective rules relating the position of the hands and elbows to the head-trunk and then tested to determine the extent to which this automated objective method replicated the clinical judgement. Clinical evaluation used video to determine whether the upper limb was free of mechanical support while the objective evaluation used 3D motion capture of the trunk and upper limbs with a classification rule. The agreement between clinical and objective classification was calculated for three conditions of a distance-from-support-surface threshold parameter in five healthy adults and five children with cerebral palsy. The unfitted (zero-threshold values) method replicated the clinical judgement in part (68.26%±15.7, adults, 48.3%±33.9 children). The fitted (level-of-support determined) agreement showed that the process could be refined using trial specific parameters (88.32%±5.3 adults, 89.84%±10.2 children). The fixed-values agreement showed high values when using general group parameters (80.80%±3.1 adults, 74.31%±21.5 children). This objective classification of the upper limb component of trunk control largely captures the clinical evaluation. It provides the first stages in development of a clinically-friendly fully automated method.

2018)Quantification of head motion in children with cerebral palsy when testing segmental trunk control.Abstract-The development of objective assessment tools to complement subjective evaluations could have a major impact in the evaluation of the consequences of neuromotor disabilities, specifically in the assessment of trunk control in children with cerebral palsy (CP). Current assessments are subjective and typically assess the general control status of a child under unbalancing situations. Only the Segmental Assessment of Trunk Control (SATCo) evaluates static, active and reactive control at six discrete trunk segmental levels and free sitting to identify the topmost trunk segment where the child does not demonstrate control. The characteristics of the SATCo make it an ideal start point to generate an objective measurement tool of control. Motion of the head is one of the main characteristics observed during a SATCo to determine the child's segmental level of control. This pilot study measured head motion during a SATCo to determine if the measurement reflected the clinical observations. Three children with different degrees of neuromotor disability were tested using the SATCo while a video camera recorded sagittal plane movements. A Head segment was defined by markers on the ear tragus and temporal fossa in vertical line with the ear when the head was aligned. Head segmental angles were calculated in relation to a real vertical, and the cumulative displacement was normalised by time (deg·s-1). One segment where external support was provided high on the trunk (Upper-Thoracic, UT) and one where external support was at the pelvis i.e. low on the trunk (Lower-Lumbar, LL) were selected for the analysis. Overall, head motion values were larger for the lower trunk tests (LL) than for the tests at the higher segment (UT) with greater external support provided. The poorer lumbar control of Child 2 and Child 3 was demonstrated in both active (39.9°·s-1, 23.3°·s-1) and reactive tests (37.3°·s-1, 13.8°·s-1). The results also showed how increasing task complexity (static to reactive) and reducing the level of support (UT to LL), increased head motion in the presence of a neuromotor disability. The results presented here corroborated the clinical evaluation of the SATCo. Head motion will have small values when children with CP are tested at a trunk segmental level where control has already been learnt or where external support is provided; children with poorer lumbar control will have an increased head motion when testing is below their trunk segmental level of assured control. This video-based approach represents a step towards the development of an objective tool for the assessment of head/trunk control in children with CP.