Causal Effects of Motor Control on Gait Kinematics After Orthopedic Surgery in Cerebral Palsy: A Machine-Learning Approach

Case report: Intensive rehabilitation program delivered before and after single-event multilevel surgery in a girl with diplegic cerebral palsy

Introduction

Diplegic cerebral palsy (CP) is often associated with musculoskeletal disorders that contribute to worsen walking function. The standard care in these cases is single-event multilevel surgery (SEMLS) followed by rehabilitation. Our aim was to investigate whether a rehabilitation program starting even before SEML could add a benefit with respect to standard postoperative programs considered by previous research.

Methods

From 2 months before to 13 months after SEMLS (except for the first month after surgery), the participant underwent a motor training focused on ROM exercises with tactile and kinaesthetic feedback. Walking performance, walking capacity, and quality-of-life were assessed before and after SEMLS at different follow-up times.

Results

Walking capacity improved 3 months after SEMLS (i.e., earlier than in current literature) and walking performance improved 12 months after SEMLS (instead of simply returning to baseline as previously reported), with a positive impact on quality-of-life.

Conclusions

This case suggests that a rehabilitation program starting even before SEMLS could add benefits over walking function and quality-of-life of children with diplegic CP compared to postoperative programs only.

Audiovisual biofeedback amplifies plantarflexor adaptation during walking among children with cerebral palsy

BACKGROUND

Biofeedback is a promising noninvasive strategy to enhance gait training among individuals with cerebral palsy (CP). Commonly, biofeedback systems are designed to guide movement correction using audio, visual, or sensorimotor (i.e., tactile or proprioceptive) cues, each of which has demonstrated measurable success in CP. However, it is currently unclear how the modality of biofeedback may influence user response which has significant implications if systems are to be consistently adopted into clinical care.

METHODS

In this study, we evaluated the extent to which adolescents with CP (7M/1F; 14 [12.5,15.5] years) adapted their gait patterns during treadmill walking (6 min/modality) with audiovisual (AV), sensorimotor (SM), and combined AV + SM biofeedback before and after four acclimation sessions (20 min/session) and at a two-week follow-up. Both biofeedback systems were designed to target plantarflexor activity on the more-affected limb, as these muscles are commonly impaired in CP and impact walking function. SM biofeedback was administered using a resistive ankle exoskeleton and AV biofeedback displayed soleus activity from electromyography recordings during gait. At every visit, we measured the time-course response to each biofeedback modality to understand how the rate and magnitude of gait adaptation differed between modalities and following acclimation.

RESULTS

Participants significantly increased soleus activity from baseline using AV + SM (42.8% [15.1, 59.6]), AV (28.5% [19.2, 58.5]), and SM (10.3% [3.2, 15.2]) biofeedback, but the rate of soleus adaptation was faster using AV + SM biofeedback than either modality alone. Further, SM-only biofeedback produced small initial increases in plantarflexor activity, but these responses were transient within and across sessions (p > 0.11). Following multi-session acclimation and at the two-week follow-up, responses to AV and AV + SM biofeedback were maintained.

CONCLUSIONS

This study demonstrated that AV biofeedback was critical to increase plantarflexor engagement during walking, but that combining AV and SM modalities further amplified the rate of gait adaptation. Beyond improving our understanding of how individuals may differentially prioritize distinct forms of afferent information, outcomes from this study may inform the design and selection of biofeedback systems for use in clinical care.

Does use of ankle foot orthoses affect the dynamic motor control index during walking in cerebral palsy and idiopathic toe walking populations?

BACKGROUND

The dynamic motor control (walk-DMC) index during walking is a measure of the complexity of muscle activation pattern. Ankle Foot Orthoses (AFO) are frequently used to improve the gait of children with Cerebral Palsy (CP) and Idiopathic Toe Walking (ITW). The purpose of this study was to assess the change in walk-DMC index secondary to AFO use.

RESEARCH QUESTION

Does the change in walk-DMC reflect the change in walking kinematics with the use of AFO.

METHODS

Individuals with diagnosis of CP or ITW with gait analysis data available for barefoot and AFO condition were retrospectively identified. For each individual, the walk-DMC index, Gait Deviation Index (GDI) and Gait Variable Scores (GVS) of knee and ankle kinematics were computed for BF and AFO conditions. Paired t-tests were used to compare key variables between BF and AFO conditions. Multi-variate stepwise regression analysis was performed to identify variables that may predict the increase in walk-DMC between BF and AFO condition.

RESULTS

253 individuals were included in the study. For CP individuals (n = 208), statistically significant but quantitatively minimal improvement was observed in walk-DMC (1 ± 9), GDI (2 ± 9) and ankle GVS (2 ± 7). For ITW individuals (n = 45), larger improvements were observed in walk-DMC (11 ± 13), GDI (9 ± 11) and ankle GVS (6 ± 7). Diagnosis of ITW, use of Solid-AFO and Posterior Leaf Spring-AFO were the significant predictor of increase in walk-DMC with AFO. Higher ankle GVS at BF condition (larger deviation from TD) led to larger increase in walk-DMC. Higher knee GVS (larger deviation from TD) led to smaller increase in walk-DMC.

SIGNIFICANCE

Use of AFO can lead to improvement in walking kinematics that is reflected in increase in walk-DMC with AFO compared to BF for ITW individuals. The change in kinematics and walk-DMC with use of AFO was minimal for CP individuals.

Directed acyclic graphs in perioperative observational research-A systematic review and critique against best practice recommendations

The Directed Acyclic Graph (DAG) is a graph representing causal pathways for informing the conduct of an observational study. The use of DAGs allows transparent communication of a causal model between researchers and can prevent over-adjustment biases when conducting causal inference, permitting greater confidence and transparency in reported causal estimates. In the era of 'big data' and increasing number of observational studies, the role of the DAG is becoming more important. Recent best-practice guidance for constructing a DAG with reference to the literature has been published in the 'Evidence synthesis for constructing DAGs' (ESC-DAG) protocol. We aimed to assess adherence to these principles for DAGs constructed within perioperative literature. Following registration on the International Prospective Register of Systematic Reviews (PROSPERO) and with adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting framework for systematic reviews, we searched the Excerpta Medica dataBASE (Embase), the Medical Literature Analysis and Retrieval System Online (MEDLINE) and Cochrane databases for perioperative observational research incorporating a DAG. Nineteen studies were included in the final synthesis. No studies demonstrated any evidence of following the mapping stage of the protocol. Fifteen (79%) fulfilled over half of the translation and integration one stages of the protocol. Adherence with one stage did not guarantee fulfilment of the other. Two studies (11%) undertook the integration two stage. Unmeasured variables were handled inconsistently between studies. Only three (16%) studies included unmeasured variables within their DAG and acknowledged their implication within the main text. Overall, DAGs that were constructed for use in perioperative observational literature did not consistently adhere to best practice, potentially limiting the benefits of subsequent causal inference. Further work should focus on exploring reasons for this deviation and increasing methodological transparency around DAG construction.

Speed-dependent biomechanical changes vary across individual gait metrics post-stroke relative to neurotypical adults

BACKGROUND

Gait training at fast speeds is recommended to reduce walking activity limitations post-stroke. Fast walking may also reduce gait kinematic impairments post-stroke. However, it is unknown if differences in gait kinematics between people post-stroke and neurotypical adults decrease when walking at faster speeds.

OBJECTIVE

To determine the effect of faster walking speeds on gait kinematics post-stroke relative to neurotypical adults walking at similar speeds.

METHODS

We performed a secondary analysis with data from 28 people post-stroke and 50 neurotypical adults treadmill walking at multiple speeds. We evaluated the effects of speed and group on individual spatiotemporal and kinematic metrics and performed k-means clustering with all metrics at self-selected and fast speeds.

RESULTS

People post-stroke decreased step length asymmetry and trailing limb angle impairment, reducing between-group differences at fast speeds. Speed-dependent changes in peak swing knee flexion, hip hiking, and temporal asymmetries exaggerated between-group differences. Our clustering analyses revealed two clusters. One represented neurotypical gait behavior, composed of neurotypical and post-stroke participants. The other characterized stroke gait behavior-comprised entirely of participants post-stroke with smaller lower extremity Fugl-Meyer scores than the post-stroke participants in the neurotypical gait behavior cluster. Cluster composition was largely consistent at both speeds, and the distance between clusters increased at fast speeds.

CONCLUSIONS

The biomechanical effect of fast walking post-stroke varied across individual gait metrics. For participants within the stroke gait behavior cluster, walking faster led to an overall gait pattern more different than neurotypical adults compared to the self-selected speed. This suggests that to potentiate the biomechanical benefits of walking at faster speeds and improve the overall gait pattern post-stroke, gait metrics with smaller speed-dependent changes may need to be specifically targeted within the context of fast walking.