Davide Monari

Altered trunk movements during gait in children with spastic diplegia: compensatory or underlying trunk control deficit?

Altered trunk movements during gait in children with CP are considered compensatory due to lower limb impairments, although scientific evidence for this assumption has not yet been provided. This study aimed to study the functional relation between trunk and lower limb movement deficits during gait in children with spastic diplegia. Therefore, the relationship between trunk control in sitting, and trunk and lower limb movements during gait was explored in 20 children with spastic diplegia (age 9.2 ± 3 yrs; GMFCS level I n=10, level II n=10). Trunk control in sitting was assessed with the Trunk Control Measurement Scale (TCMS), a clinical measure that reflects the presence of an underlying trunk control deficit. Trunk movements during gait were measured with a recently developed trunk model including the pelvis, thorax, head, shoulder line and spine. Lower limb movements were assessed with the Plug-in-Gait model (Vicon(®)). Range of motion (ROM) of the different trunk segments was calculated, as well as the Trunk Profile Score (TPS) and Trunk Variable Scores (TVSs). Similarly, the Gait Profile Score (GPS) and Gait Variable Scores (GVSs) were calculated to describe altered lower limb movements during gait. Correlation analyses were performed between the presence of impaired trunk control in sitting (TCMS) and altered trunk movements during gait (ROM, TPS/TVSs) and between these altered trunk movements and lower limb movements (GPS/GVSs) during gait. A poorer performance on the TCMS correlated with increased ROM and TPS/TVSs, particularly for the thorax, indicating the presence of an underlying trunk control deficit. No significant correlation was found between the TPS and GPS, suggesting that overall trunk and lower limb movement deficits were not strongly associated. Only few correlations between specific lower limb deficits (GVSs for hip ab/adduction, knee flexion/extension and ankle flexion/extension) and TVSs for thorax lateral bending and rotation were found. This study provided first evidence that the altered trunk movements observed during gait should not be solely considered compensatory due to lower limb impairments, but that these may also partially reflect an underlying trunk control deficit. A better understanding of underlying trunk control deficits in children with CP may facilitate targeted therapy planning and ultimately can optimize a childs functionality.

Three-dimensional head and trunk movement characteristics during gait in children with spastic diplegia

This study uses a recently developed trunk model to determine which head and trunk kinematic parameters differentiate children with spastic diplegia from typically developing (TD) children while walking. Differences in head and trunk parameters in relation to the severity of the motor involvement (GMFCS levels) were additionally examined. The trunk model consisted of five segments (pelvis, thorax, head, shoulder line, spine). Discrete kinematic parameters (ROM, mean position) and angular waveforms were compared between 20 children with spastic diplegia (age 9.8 years±2.9 years; GMFCS I: n=10, GMFCS II: n=10) and 20 individually age-matched TD children (9.7 years±3 years). A new measure for overall trunk pathology, the trunk profile score (TPS), was proposed and included in the comparative analysis. Compared to TD children, children with GMFCS II showed a significantly higher TPS and increased ROM for pelvis tilt, for thorax and head in nearly all planes, and the angle of kyphosis. In children with GMFCS I, only ROM of thorax lateral bending was significantly increased. Sagittal ROM differentiated best between GMFCS levels, with higher ROM found in children with GMFCS II. Current results provide new insights into head and trunk kinematics during gait in children with spastic diplegia.

The relation between spasticity and muscle behavior during the swing phase of gait in children with cerebral palsy

There is much debate about how spasticity contributes to the movement abnormalities seen in children with spastic cerebral palsy (CP). This study explored the relation between stretch reflex characteristics in passive muscles and markers of spasticity during gait. Twenty-four children with CP underwent 3D gait analysis at three walking velocity conditions (self-selected, faster and fastest). The gastrocnemius (GAS) and medial hamstrings (MEHs) were assessed at rest using an instrumented spasticity assessment that determined the stretch-reflex threshold, expressed in terms of muscle lengthening velocity. Muscle activation was quantified with root mean square electromyography (RMS-EMG) during passive muscle stretch and during the muscle lengthening periods in the swing phase of gait. Parameters from passive stretch were compared to those from gait analysis. In about half the children, GAS peak muscle lengthening velocity during the swing phase of gait did not exceed its stretch reflex threshold. In contrast, in the MEHs the threshold was always exceeded. In the GAS, stretch reflex thresholds were positively correlated to peak muscle lengthening velocity during the swing phase of gait at the faster (r = 0.46) and fastest (r = 0.54) walking conditions. In the MEHs, a similar relation was found, but only at the faster walking condition (r = 0.43). RMS-EMG during passive stretch showed moderate correlations to RMS-EMG during the swing phase of gait in the GAS (r = 0.46-0.56) and good correlations in the MEHs (r = 0.69-0.77) at all walking conditions. RMS-EMG during passive stretch showed no correlations to peak muscle lengthening velocity during gait. We conclude that a reduced stretch reflex threshold in the GAS and MEHs constrains peak muscle lengthening velocity during gait in children with CP. With increasing walking velocity, this constraint is more marked in the GAS, but not in the MEHs. Hyper-activation of stretch reflexes during passive stretch is related to muscle activation during the swing phase of gait, but has a limited contribution to reduced muscle lengthening velocity during swing. Larger studies are required to confirm these results, and to investigate the contribution of other impairments such as passive stiffness and weakness to reduced muscle lengthening velocity during the swing phase of gait.

Biomechanical gait features associated with hip osteoarthritis: Towards a better definition of clinical hallmarks.

Critical appraisal of the literature highlights that the discriminative power of gait‐related features in patients with hip osteoarthritis (OA) has not been fully explored. We aimed to reduce the number of gait‐related features and define the most discriminative ones comparing the three‐dimensional gait analysis of 20 patients with hip osteoarthritis (OA) with those of 17 healthy peers. First, principal component analysis was used to reduce the high‐dimensional gait data into a reduced set of interpretable variables for further analysis, including tests for group differences. These differences were indicative for the selection of the top 10 variables to be included into linear discriminant analysis models (LDA). Our findings demonstrated the successful data reduction of hip osteoarthritic‐related gait features with a high discriminatory power. The combination of the top variables into LDA models clearly separated groups, with a maximum misclassification error rate of 19%, estimated by cross‐validation. Decreased hip/knee extension, hip flexion and internal rotation moment were gait features with the highest discriminatory power. This study listed the most clinically relevant gait features characteristics of hip OA. Moreover, it will help clinicians and physiotherapists understand the movement pathomechanics related to hip OA useful in the management and design of rehabilitation intervention.

Reliability of head and trunk kinematics during gait in children with spastic diplegia

This study describes the reliability of a clinically oriented model for three-dimensional movement analysis of head and trunk movements in children with spastic diplegia. The model consists of five rigid segments (head, thorax, pelvis, shoulder line, spine) and includes a detailed analysis of spinal segmental movements. Within and between session reliability during gait was tested in 10 children with spastic diplegia (6-14yrs). Reliability of discrete parameters was assessed with the intraclass correlation coefficient (ICC) and similarity of thorax and pelvis waveforms with the coefficient of multiple correlation (CMC). Measurement errors were calculated for all parameters (SEM, σ). Results indicated acceptable within and between session reliability of discrete parameters for thorax, pelvis, shoulder line, angle of kyphosis and the majority of the spinal segmental angles, reflected by low SEMs (<4°) and most ICCs>0.60. Within and between session waveform errors were below 4°. CMCs ranged from poor to very good, with highest values for movements in the frontal and transversal planes. The angle of lordosis showed lower between session reliability for several discrete parameters, although waveform errors were still below 5°. Head parameters showed lower overall reliability. The results of this study support the reliability of the proposed model. Head kinematic parameters should be interpreted with caution, due to difficulties in standardization. Accurate palpation of the spinal markers, especially the lumbar spine, is critical and demands thorough training of the assessor.

The reliability and validity of a clinical 3D freehand ultrasound system

BACKGROUND AND OBJECTIVE Acquiring large anatomical volumes in a feasible manner is useful for clinical decision-making. A relatively new technique called 3D freehand ultrasonography is capable of this by combining a conventional 2D ultrasonography system. Currently, a thorough analysis of this technique is lacking, as the analyses are dependent on the software implementation details and the choice of measurement systems. Therefore this study starts by making this implementation available under the form of an open-source software library to perform 3D freehand ultrasonography. Following that, reliability and validity analyses of extracting volumes and lengths will be carried out using two independent motion-tracking systems. METHODS A PC-based ultrasonography device and two optical motion-tracking systems were used for data acquisition. An in-house software library called Py3DFreeHandUS was developed to reconstruct (off-line) the corresponding data into one 3D data set. Reliability and validity analyses of the entire experimental set-up were performed by estimating the volumes and lengths of ground truth objects. Ten water-filled balloons and six cross-wires were used. Repeat measurements were also performed by two experienced operators. RESULTS The software library Py3DFreeHandUS is available online, along with the relevant documentation. The reliability analyses showed high intra- and inter-operator intra-class correlation coefficient results for both volumes and lengths. The accuracy analysis revealed a discrepancy in all cases of around 3%, which corresponded to 3 ml and 1 mm for volume and length measurements, respectively. Similar results were found for both of the motion-tracking systems. CONCLUSIONS The undertaken analyses for estimating volume and lengths acquired with 3D freehand ultrasonography demonstrated reliable design measurements and suitable performance for applications that do not require sub-mm and -ml accuracy.

Three-dimensional kinematics of the scapula and trunk, and associated scapular muscle timing in individuals with stroke

Poor scapulothoracic control is a risk for developing shoulder pathology, but has received little attention so far in individuals with stroke (IwS). Trunk and scapular kinematics and surface muscle activity were measured in 15 healthy controls and 18 IwS during a low and high forward flexion (FF). Group-differences in trunk and scapular kinematics were assessed during low and high FF using a t-test (independent samples). Differences in muscle onset and offset time relative to movement start (both FF tasks) were determined using a mixed model taking into account the different groups and muscles. Recruitment patterns per group and task were described based on significant differences between muscles. In IwS, earlier lower trapezius and late infraspinatus offset were found during low FF, as well as a later onset and earlier offset of serratus anterior. For low FF, significantly more trunk axial rotation was found in IwS during both elevation and lowering. During high FF, IwS showed significantly less scapular posterior tilt during elevation and more scapular lateral rotation during lowering. IwS demonstrated adaptive muscle timing with earlier initiation and late inactivation of lower trapezius and infraspinatus, possibly to compensate for a late activation and early deactivation of the serratus anterior and to establish as such the correct pattern of scapulothoracic movement.

Evaluation of stair motion contributes to new insights into hip osteoarthritis-related motion pathomechanics

Stair motion in the presence of hip osteoarthritis (OA) has received less attention than level walking. Its more strenuous aspect may shed the light on different locomotor strategies when compared to walking. We, therefore, aimed to define stair motion features associated to hip OA and to evaluate whether these specific features would differ from level walking and better characterize the hip pathological condition. Principal component and linear discriminant analyses were, respectively, used as data reduction and classification techniques. Our study highlighted that most of stair motion features associated to hip OA were similar to the ones of walking. Stair descent presented with the lowest misclassification error rate, ranging from 12% to 19% (estimated by cross‐validation). But, features that may be considered as a mechanism to reduce demand on the hip abductors were found to be more important in the stair ascent condition. This was reflected by both, greater importance in the classification rule and variance compared with walking, that is, decreased hip internal rotation moment at mid‐stance (72.50% vs. 57.63%) and increased trunk lateroflexion toward affected side (56.43% vs. 29.37%). This study emphasized the importance of investigating stair motion in hip osteoarthritic population by highlighting specific locomotor strategies.

Inter- and intrarater clinician agreement on joint motion patterns during gait in children with cerebral palsy.

This study aimed to quantify the inter‐ and intrarater clinician agreement on joint motion patterns in children with spastic cerebral palsy (CP), which were recently specified by a Delphi consensus study. It also examined whether experience with three‐dimensional gait analysis (3DGA) is a prerequisite for using the patterns.

Hip movement pathomechanics of patients with hip osteoarthritis aim at reducing hip joint loading on the osteoarthritic side

This study aims at defining gait pathomechanics in patients with hip osteoarthritis (OA) and their effect on hip joint loading by combining analyses of hip kinematics, kinetics and contact forces during gait. Twenty patients with hip OA and 17 healthy volunteers matched for age and BMI performed three-dimensional gait analysis. Hip OA level was evaluated based on plane radiographs using the Tönnis classification. Hip joint kinematics, kinetics as well as hip contact forces were calculated. Waveforms were time normalized and compared between groups using statistical parametric mapping analysis. Patients walked with reduced hip adduction angle and reduced hip abduction and external rotation moments. The work generated by the hip abductors during the stance phase of gait was largely decreased. These changes resulted in a decrease and a more vertical and anterior orientation of the hip contact forces compared to healthy controls. This study documents alterations in hip kinematics and kinetics resulting in decreased hip loading in patients with hip OA. The results suggested that patients altered their gait to increase medio-lateral stability, thereby decreasing demand on the hip abductors. These findings support discharge of abductor muscles that may bear clinical relevance of tailored rehabilitation targeting hip abductor muscles strengthening and gait retraining.