Coordination between pelvis and shoulder girdle during walking in bilateral cerebral palsy

Analysis of cerebral palsy gait based on movement primitives

BACKGROUND

Cerebral palsy is the most prevalent motor disorder among children. Despite extensive studies on motor modularity of gait of children with cerebral palsy, kinematic modularity of their gait has not been addressed which is the main goal of this study.

METHODS

The kinematics of the gait of 13 typical development children and 188 children with cerebral palsy was captured and analyzed, where the cerebral palsy children were grouped into True, Jump, Apparent, and Crouch. Non-negative matrix factorization method was used to extract the kinematic modulus of each group, which were then clustered to find their characteristic movement primitives. The movement primitives of groups were then matched based on the similarity of their activation profiles.

FINDINGS

The number of movement primitives was three for the Crouch group, four for the other cerebral palsy groups, and five for the typical development group. Compared to the typical development children, the kinematic modules and activations of the cerebral palsy groups involved higher variability and co-activation, respectively (P < 0.05). Three temporally matched movement primitives were shared by all groups, but with altered structures.

INTERPRETATION

The gait of children with cerebral palsy involved lower complexity and higher variability due to the reduced and inconsistent kinematic modularity. Three basic movement primitives were sufficient to prodcue the overall gait kinematics, as observed in the Crouch group. Other movement primitives, were responsible for providing smooth transitions between basic movement primitives, as seen in more complex gait patterns.

Assessing the contribution of lower limb mobilization, in the supine position, on shoulder-pelvis girdles dissociation

BACKGROUND

Several articular, muscular and neurological diseases generate mobility loss in the shoulder and pelvis girdles. Joint mobilization contributes to improving shoulder-pelvis girdles dissociation, but current mobilization techniques are not always successful and standardized. A robotic medical device, DPA Med®, by inducing trunk mobilization through lower limb oscillation has been developed for producing such a shoulder-pelvis girdles dissociation and is already used worldwide in rehabilitation hospitals.

RESEARCH QUESTION

To determine the optimal lower limb oscillation frequency that generated the best shoulder-pelvis girdles dissociation using the DPA Med® device.

METHODS

Thirty healthy adult volunteers (mean age: 38.6 [SD 15.2] years, mean height: 174 [SD 11.9] cm, mean body mass: 70.3 [SD 14.7] kg) participated in this prospective study. A kinematic analysis quantified pelvic and shoulder girdle mobility (rotation and lateral tilt) at different DPA Med® frequencies, from 0.5 Hz to 1 Hz. A visual analysis of the lower limb movement was also performed, using video sensors, to better understand the kinematics involved.

RESULTS

All DPA Med® frequencies have shown significant shoulder-pelvis girdles dissociation (p < 0.05). This study established an optimal oscillation frequency with the minimal interindividual variability at 0.808 Hz. It induced pelvic mobility similar to that of normal gait, in the transverse and frontal planes (10.3°, SD 2.9°, and 12.0°, SD 2.2°, respectively). This trunk mobility was achieved by producing a lemniscate-shaped motion in the lower limbs (an eight-shaped motion in the transverse plane).

SIGNIFICANCE

This study has shown that the DPA Med® device is able to induce shoulder-pelvis girdles dissociation similar to that of normal gait and allowed to establish the existence of an optimal DPA Med® oscillation frequency for lower limb mobility at 0.808 Hz. Further studies are required to evaluate its potentially benefits on gait disorders.

Coordination of Axial Trunk Rotations During Gait in Low Back Pain. A Narrative Review

Chronic low back pain patients have been observed to show a reduced shift of thorax-pelvis relative phase towards out-of-phase movement with increasing speed compared to healthy controls. Here, we review the literature on this phase shift in patients with low back pain and we analyze the results presented in literature in view of the theoretical motivations to assess this phenomenon. Initially, based on the dynamical systems approach to movement coordination, the shift in thorax-pelvis relative phase with speed was studied as a self-organizing transition. However, the phase shift is gradual, which does not match a self-organizing transition. Subsequent emphasis in the literature therefore shifted to a motivation based on biomechanics. The change in relative phase with low back pain was specifically linked to expected changes in trunk stiffness due to 'guarded behavior'. We found that thorax-pelvis relative phase is affected by several interacting factors, including active drive of thorax rotation through trunk muscle activity, stride frequency and the magnitude of pelvis rotations. Large pelvis rotations and high stride frequency observed in low back pain patients may contribute to the difference between patients and controls. This makes thorax-pelvis relative phase a poor proxy of trunk stiffness. In conclusion, thorax-pelvis relative phase cannot be considered as a collective variable reflecting the orderly behaviour of a complex underlying system, nor is it a marker of specific changes in trunk biomechanics. The fact that it is affected by multiple factors may explain the considerable between-subject variance of this measure in low back pain patients and healthy controls alike.

Gait deficits and dynamic stability in children and adolescents with cerebral palsy: A systematic review and meta-analysis

BACKGROUND

Studies have demonstrated that ambulatory children and adolescents with cerebral palsy demonstrate atypical gait patterns. Out of numerous gait variables, identification of the most deteriorated gait parameters is important for targeted and effective gait rehabilitation. Therefore, this study aimed to identify the gait parameters with the most discriminating nature to distinguish cerebral palsy gait from normal gait.

METHODS

Multiple databases were searched to include studies on ambulatory children and adolescents with cerebral palsy that included gait (spatio-temporal, kinematic, and kinetic) and dynamic stability variables.

FINDINGS

Of 68 studies that met the inclusion criteria, 35 studies were included in the meta analysis. Effect size was used to assess the discriminative strength of each variable. A large effect (≥ 0.8) of cerebral palsy on double limb support time (Standardized Mean Difference = 0.98), step length (Standardized Mean Difference = 1.65), step width (Standardized Mean Difference = 1.21), stride length (Standardized Mean Difference = 1.75), and velocity (Standardized Mean Difference = 1.42) was observed at preferred-walking speed. At fast-walking speed, some gait variables (i.e. velocity and stride length) exhibited larger effect size compared to preferred-walking speed. For some kinematic variables (e.g. range of motion of pelvis), the effect size varied across the body planes.

INTERPRETATION

Our systematic review detects the most discriminative features of cerebral palsy gait. Non-uniform effects on joint kinematics across the anatomical planes support the importance of 3D gait analysis. Differential effects at fast versus preferred speeds emphasize the importance of measuring gait at a range of speeds.