Crouch gait or flexed-knee gait in cerebral palsy: Is there a difference? A systematic review

Walking representation and simulation based on multi-source image fusion and multi-agent reinforcement learning for gait rehabilitation

In the formulation of strategies for walking rehabilitation, achieving precise identification of the current state and making rational predictions about the future state are crucial but often unrealized. To tackle this challenge, our study introduces a unified framework that integrates a novel 3D walking motion capture method using multi-source image fusion and a walking rehabilitation simulation approach based on multi-agent reinforcement learning. We found that, (i) the proposal achieved an accurate 3D walking motion capture and outperforms other advanced methods. Experimental evidence indicates that, compared to similar visual skeleton tracking methods, the proposed approach yields results with higher Pearson correlation (r=0.93), intra-class correlation coefficient (ICC(2,1)=0.91), and narrower confidence intervals ([0.90,0.95] for r, [0.88,0.94] for ICC(2,1)) when compared to standard results. The outcomes of the proposed approach also exhibit commendable correlation and concurrence with those obtained through the IMU-based skeleton tracking method in the assessment of gait parameters ([0.85,0.89] for r, [0.75,0.81] for ICC(2,1)); (ii) multi-agent reinforcement learning has the potential to be used to solve the simulation task of gait rehabilitation. In mimicry experiment, our proposed simulation method for gait rehabilitation not only enables the intelligent agent to converge from the initial state to the target state, but also observes evolutionary patterns similar to those observed in clinical practice through motor state resolution. This study offers valuable contributions to walking rehabilitation, enabling precise assessment and simulation-based interventions, with potential implications for clinical practice and patient outcomes.

A dynamic foot model for predictive simulations of human gait reveals causal relations between foot structure and whole-body mechanics

The unique structure of the human foot is seen as a crucial adaptation for bipedalism. The foot's arched shape enables stiffening the foot to withstand high loads when pushing off, without compromising foot flexibility. Experimental studies demonstrated that manipulating foot stiffness has considerable effects on gait. In clinical practice, altered foot structure is associated with pathological gait. Yet, experimentally manipulating individual foot properties (e.g. arch height or tendon and ligament stiffness) is hard and therefore our understanding of how foot structure influences gait mechanics is still limited. Predictive simulations are a powerful tool to explore causal relationships between musculoskeletal properties and whole-body gait. However, musculoskeletal models used in three-dimensional predictive simulations assume a rigid foot arch, limiting their use for studying how foot structure influences three-dimensional gait mechanics. Here, we developed a four-segment foot model with a longitudinal arch for use in predictive simulations. We identified three properties of the ankle-foot complex that are important to capture ankle and knee kinematics, soleus activation, and ankle power of healthy adults: (1) compliant Achilles tendon, (2) stiff heel pad, (3) the ability to stiffen the foot. The latter requires sufficient arch height and contributions of plantar fascia, and intrinsic and extrinsic foot muscles. A reduced ability to stiffen the foot results in walking patterns with reduced push-off power. Simulations based on our model also captured the effects of walking with anaesthetised intrinsic foot muscles or an insole limiting arch compression. The ability to reproduce these different experiments indicates that our foot model captures the main mechanical properties of the foot. The presented four-segment foot model is a potentially powerful tool to study the relationship between foot properties and gait mechanics and energetics in health and disease.

Identifying treatment non-responders based on pre-treatment gait characteristics - A machine learning approach

Background

Paediatric movement disorders such as cerebral palsy often negatively impact walking behaviour. Although clinical gait analysis is usually performed to guide therapy decisions, not all respond positively to their assigned treatment. Identifying these individuals based on their pre-treatment characteristics could guide clinicians towards more appropriate and personalized interventions. Using routinely collected pre-treatment gait and anthropometric features, we aimed to assess whether standard machine learning approaches can be effective in identifying patients at risk of negative treatment outcomes.

Methods

Observational data of 119 patients with movement disorders were retrospectively extracted from a local clinical database, comprising sagittal joint angles and spatiotemporal parameters, derived from motion capture data pre- and post-treatment (physiotherapy, orthosis, botulin toxin injections, or surgery). Participants were labelled based on their change in gait profile score (GPS, non-responders with a decline in GPS of <1.6° vs. responders). Their pre-treatment features (sagittal joint angles, spatiotemporal parameters, anthropometrics) were used to train a support vector machine classifier with 5-fold cross-validation and Bayesian optimization within a MATLAB-based Classification Learner App.

Results

An average accuracy of 88.2 ± 0.5 % was achieved for identifying participants whose gait will not respond to treatment, with 64 % true negative rate and an area under the curve of 88 %.

Conclusion

Overall, a classical machine learning model was able to identify patients at risk of not responding to treatment, based on gait features and anthropometrics collected prior to treatment. The output of such a model could function as a warning signal, notifying clinicians that a certain individual might not respond well to the standard of care and that a more personalized intervention might be needed.

A prospective assessment of gait kinematics and related clinical examination measures in cerebral palsy crouch gait

Background While prospectively assessed crouch gait in cerebral palsy (CP) does not necessarily progress, prospective changes in clinical examination measures have not been reported. This study prospectively examined the association between selected clinical examination variables and change in crouch gait in a cohort with bilateral CP. Methods Inclusion criteria were a diagnosis of ambulant bilateral CP, knee flexion at mid-stance >19 0 and a minimum of two-years between gait analyses. The change in kinematic variables was assessed using Statistical Parameter Mapping (SPM) and changes in clinical measures using appropriate paired tests. Linear regression examined the association between progression of crouch and clinical examination variables. Results There was no mean change in crouch in 27 participants over 3.29 years. However, there was significant variability within this group. Clinical hamstring tightness (60.00 0 to 70.48 0, p<0.01) and external knee rotation during stance (SPM analysis, p<0.001) increased but there was no association between changes in clinical examination variables and changes in crouch (p-values 0.06 - 0.89).    Conclusions This prospective study found no association between the changes in clinical examination variables and changes in crouch highlighting the likely multi-factorial aetiology of this gait pattern and the need for larger prospective studies. The variability crouch gait progression among the 27 participants highlights the pitfall of group mean values in such a heterogeneous population.

A prospective assessment of gait kinematics and related clinical examination measures in cerebral palsy crouch gait

Background While prospectively assessed crouch gait in cerebral palsy (CP) does not necessarily progress, prospective changes in clinical examination measures have not been reported. This study prospectively examined the association between selected clinical examination variables and change in crouch gait in a cohort with bilateral CP. Methods Inclusion criteria were a diagnosis of ambulant bilateral CP, knee flexion at mid-stance >190 and a minimum of two-years between gait analyses. The change in kinematic variables was assessed using Statistical Parameter Mapping (SPM) and changes in clinical measures using appropriate paired tests. Linear regression examined the association between progression of crouch and clinical examination variables. Results There was no mean change in crouch in 27 participants over 3.29 years. However, there was significant variability within this group. Clinical hamstring tightness (60.000 to 70.480, p<0.01) and external knee rotation during stance (SPM analysis, p<0.001) increased but there was no association between changes in clinical examination variables and changes in crouch (p-values 0.06 - 0.89).    Conclusions The variability crouch gait progression highlights the pitfall of group mean values in such a heterogeneous population.  The lack of association between changes in clinical examination variables and changes in crouch highlights the multi-factorial aetiology of this gait pattern and the need for larger prospective studies.

Gait status 26-35 years after selective dorsal rhizotomy: A 9 year follow up study

BACKGROUND

Although the short-term outcomes of selective dorsal rhizotomy (SDR) in children with cerebral palsy (CP) have been well documented, less is known about the long-term benefits of SDR, especially while aging.

RESEARCH QUESTION

Does the gait of adults with CP, who underwent SDR in childhood, change during a nine-year aging follow-up period? Do associations exists between the gait deviation index (GDI) and contextual factors at follow-up?

METHODS

Three-dimensional motion data was captured (Vicon system) of 26 adults (10 female) with CP and spastic diplegia at baseline (17-to-26 years post-SDR) and at nine-year follow-up (26-to-35 years post-SDR), as well as 41 matched typically developed (TD) adults used for reference data. Kinematic, non-dimensional temporal distance and GDI parameters were determined, and associations with contextual factors were studied.

RESULTS

At follow-up the adults with CP had a (median [interquartile ranges]) age of 35.8 [34.2-41.2] years and classified as Gross Motor Function Classification System (GMFCS) level I (n = 13), level II (n = 10) and level III (n = 3). Overall no clinically relevant change in gait quality (GDI) was detected over the nine-year follow-up period. However, small changes were found in hip and knee range of motion, peak knee flexion and walking speed. In line with the baseline study, a number of gait parameters were different to TD adults. The only association found was between GDI and GMFCS at follow-up (r = 0.64, p < 0.01).

SIGNIFICANCE

The overall walking pattern of the adults with CP who underwent SDR in childhood was characterised by mild crouch gait with minimal signs of spasticity, confirming former physical examination findings. Some small changes in certain gait parameters were determined, though clinically the gait quality remained stable during the nine-year aging period. This finding supports the stability of the gait pattern during mid-life in adults with CP, who met the strict SDR selection criteria.

Evaluation of Multilevel Surgeries in Children With Spastic Cerebral Palsy Based on Surface Electromyography

The root mean square (RMS) of the surface electromyography (sEMG) signal can respond to neuromuscular function, which displays a positive correlation with muscle force and muscle tension under positive and passive conditions, respectively. The purpose of this study was to investigate the changes in muscle force and tension after multilevel surgical treatments, functional selective posterior rhizotomy (FSPR) and tibial anterior muscle transfer surgery, and evaluate their clinical effect in children with spastic cerebral palsy (SCP) during walking. Children with diplegia (n = 13) and hemiplegia (n = 3) with ages from 4 to 18 years participated in this study. They were requested to walk barefoot at a self-selected speed on a 15-m-long lane. The patient's joints' range of motion (ROM) and sEMG signal of six major muscles were assessed before and after the multilevel surgeries. The gait cycle was divided into seven phases, and muscle activation state can be divided into positive and passive conditions during gait cycle. For each phase, the RMS of the sEMG signal amplitude was calculated and also normalized by a linear envelope (10-ms running RMS window). The muscle tension of the gastrocnemius decreased significantly during the loading response, initial swing, and terminal swing (p < 0.05), which helped the knee joint to get the maximum extension when the heel is on the ground and made the heel land smoothly. The muscle force of the gastrocnemius increased significantly (p < 0.05) during the mid-stance, terminal stance, and pre-swing, which could generate the driving force for the human body to move forward. The muscle tension of the biceps femoris and semitendinosus decreased significantly (p < 0.05) during the terminal stance, pre-swing, and initial swing. The decreased muscle tension could relieve the burden of the knee flexion when the knee joint was passively flexed. At the terminal swing, the muscle force of the tibial anterior increased significantly (p < 0.05), which could improve the ankle dorsiflexion ability and prevent foot drop and push forward. Thus, the neuromuscular function of cerebral palsy during walking can be evaluated by the muscle activation state and the RMS of the sEMG signal, which showed that multilevel surgical treatments are feasible and effective to treat SCP.

A New Method for Postural Misalignment of a 6-Year-Old Girl With Cerebral Palsy: A Case Report

Objective

To demonstrate the effects of a newly designed postural alignment relearning system on postural control dysfunction in a typical patient with cerebral palsy (CP).

Design

Evaluation before and after 8 weeks of Constraint Standing Training 3-dimensional postural alignment relearning system.

Setting

Department of Rehabilitation Medicine.

Participant

A 6-year-old girl with CP and postural misalignment on Gross Motor Function Classification System level I.

Interventions

Constraint Standing Training for 8 weeks to correct postural misalignment.

Main Outcome Measures

Parameters of lateral plain radiographs in static standing, posturography measurements in standing and walking, motor ability (Gross Motor Function Measure-88 [GMFM-88] scores, manual muscle testing [MMT] scores, muscle architecture), and gait kinematic parameters (40 3-dimensional parameters of arms, trunk, waist, and lower limbs).

Results

Knee hyperextension angle in static standing; peaks of knee flexion angle (KFA) when walking, hip flexion angle and ankle flexion angle in dynamic standing; and the KFA at initial contact in gait cycle all decreased significantly (P<.01). Scores of GMFM-88 sections D and E and MMT of 5 core stability muscles improved (P<.01). The velocities and range of motion of the arms, the 3-dimensinoal range of motion of the trunk and waist, and most of the parameters of the lower limbs showed statistically significant change (P<.01). Bilateral muscle thickness did not change significantly after the treatment (P=.738 left, P=.978 right), but the gluteus maximus morphology was changed: the muscle fibers became rounder, the interfiber space decreased, and the border lines of the muscle fibers got clearer.

Conclusions

Postural alignment, motor ability, and gait may be homologous external manifestations of more fundamental core abilities, referring to correct standing posture cognition, muscle activation, and postural unconsciousness. Constraint Standing Training 3-dimensional postural alignment relearning system aimed to improve the static and dynamic standing control ability, may fix postural misalignment and improve motor ability and flexed-knee gait. Future work should use Constraint Standing Training with patients with different kinds of misalignment, choose sensitive indicators, observe the duration of each step, and reveal the mechanism causes postural misalignment.

Short walking exercise leads to gait changes and muscle fatigue in children with cerebral palsy who walk with jump gait

OBJECTIVE

To evaluate kinematic changes and muscle fatigue in jump gait during a walking exercise, and the relationship between kinematic changes and muscle fatigue and strength.

DESIGN

This preliminary study included ten children with cerebral palsy (CP) who walk with jump gait. Hip and knee maximal isometric muscle strength were measured using a dynamometer. Then, lower-limb kinematics and electromyography were collected while children walked continuously for 6-min at their self-selected speed. Electromyography median frequency and lower-limb joint angles were compared between the first and the sixth minute of the walking exercise using T-test and Wilcoxon rank test. Relationship between kinematic changes and muscle strength and changes in electromyography median frequency were assessed using correlation analyses.

RESULTS

During stance, maximal knee flexion significantly increased at the sixth minute (P=0.01) and was associated with knee extensor muscle weakness (rho=-0.504, P=0.03). Muscle fatigue was only observed in gluteus medius muscle (P=0.01).

CONCLUSIONS

Children with CP who walked with jump gait and who had knee extensor weakness were more prone to an increase in knee flexion during a continuous walk. The fatigue in the gluteus medius muscle suggests that physical intervention should target the endurance of this muscle to improve jump gait.