Kinematic and Functional Gait Changes After the Utilization of a Foot Drop Stimulator in Pediatrics

Design and characterization of a variable-stiffness ankle-foot orthosis

BACKGROUND

Ankle-foot orthoses (AFOs) are a type of assistive device that can improve the walking ability of individuals with neurological disorders. Adjusting stiffness is a common way to customize settings according to individuals' impairment.

OBJECTIVE

This study aims to design a variable-stiffness AFO by stiffness module and characterize the AFO stiffness range to provide subject-specific settings for the users.

METHODS

We modeled AFO using bending beams with varying fulcrum positions to adjust the stiffness. To characterize the stiffness range and profile, we used the superposition method to generate the theoretical model to analyze the AFO numerically. The intrinsic deformation of the bending beam in the AFO is considered a combination of 2 bending deformations to replicate actual bending conditions. The corresponding experiments in different fulcrum positions were performed to compare with and optimize the theoretical model. The curve fitting method was applied to tune the theoretical model by adding a fulcrum position-related coefficient.

RESULTS

The AFO stiffness increased as the fulcrum moved to the proximal position. The maximum stiffness obtained was 1.77 Nm/° at a 6-cm fulcrum position, and the minimum stiffness was 0.82 Nm/° at a 0.5-cm fulcrum position with a 0.43-cm thick fiberglass beam. The corresponding theoretical model had maximum and minimum stiffness of 1.71 and 0.80 Nm/°, respectively. The theoretical model had a 4.08% difference compared with experimental values.

CONCLUSIONS

The stiffness module can provide adjustable stiffness with the fulcrum position and different kinds of fiberglass bars, especially the thickness and material of the beam. The theoretical model with different fulcrum positions can be used to profile the real-time stiffness of the AFO in a dynamic motion and to determine the appropriate dimensions of the bending beam.

Gait analysis of leprosy patients with foot drop using principal component analysis

BACKGROUND

Peripheral nerve injury caused by leprosy can lead to foot drop, resulting in an altered gait pattern that has not been previously described using 3D gait analysis.

METHODS

Gait kinematics and dynamics were analyzed in 12 patients with unilateral foot drop caused by leprosy and in 15 healthy controls. Biomechanical data from patients' affected and unaffected limbs were compared with controls using inferential statistics and a standard distance, based on principal components analysis (PCA).

FINDINGS

Patients walked slower than controls (0.8 ± 0.2 vs. 1.1 ± 0.2 m/s, p = 0.003), with a reduced stance and increased swing percentage. The affected limb increased (p < 0.05) plantar flexion at the initial contact (-16.8^o ± 8.3), terminal stance (-29.1^o ± 11.5), and swing (-12.4^o ± 6.2) in the affected limb compared to unaffected (-6.6^o ± 10.3; -14.6^o ± 11.6; 2.4^o ± 7.6) and controls (-5.4^o ± 2.5; -18.8^o ± 5.8; -1.4^o ± 3.9). Increased pelvic tilt and knee adduction/abduction range, with lower hip adduction, were observed. The second peak of ground reaction force (98.6 ± 5.2 %BW), ankle torque (0.99 ± 0.33 Nm/kg), and net ankle work in stance (-0.03 ± 5.4 J/Kg) decreased in the affected limb compared to controls (104.1 ± 5.5 %BW; 1.24 ± 0.4 Nm/kg; -4.58 ± 5.19 J/kg; p < 0.05). There were decreasing multivariate standard distances in the affected limb compared with the unaffected and controls. PCA loading factors highlighted the major differences between groups.

INTERPRETATION

Leprosy patients with foot drop presented altered gait patterns in affected and unaffected limbs. There were remarkable differences in ankle kinematics and dynamics. Rehabilitation devices, such as ankle foot orthosis or tendon transfer surgeries to increase ankle dorsiflexion, could benefit these patients and reduce deviations from normal gait.

Investigating the effects of conventional thermoplastic ankle-foot and the neoprene ankle-foot orthoses on the kinetics and kinematics of gait in people with foot drop following traumatic injury of the peroneal nerve: A pilot study

BACKGROUND

Adopting compensatory walking mechanisms by people with foot drop due to traumatic injury of the peroneal nerve costs altered gait kinetics and kinematics. Therefore, orthoses are generally recommended to minimize the deployment of compensatory gait mechanisms.

OBJECTIVES

To investigate the immediate effects of a low-cost, Neoprene Ankle-Foot Orthosis (NAFO) and the thermoplastic ankle-foot orthosis (AFO) with the shoe-only condition on kinematics and kinetics of gait of people with foot drop following peroneal nerve traumatic injury.

METHODS

Seven people with foot drop due to traumatic injury of the peroneal nerve were included in this study. The gait kinematics and kinetics of the participants were investigated in three different conditions: shoe-only, AFO + shoe, and NAFO + shoe using a six-camera, motion-analysis system, and a force platform. A Friedman two-way ANOVA by ranks model was employed to compare different testing conditions.

RESULTS

The ankle angle at the initial contact was significantly different between shoe-only condition and AFO (p < 0.00). The plantarflexion angle in both orthotic designs was reduced significantly compared to the shoe-only condition (p < 0.00). The maximum ankle dorsiflexion angle during the stance phase and maximum knee flexion angle during the stance and swing phases were not statistically significant for all testing conditions (p > 0.00). A significant difference was observed for the 1st-rise of the ground reaction force's vertical component between the NAFO and the AFO (p < 0.00). Likewise, a significant difference was observed for the 2nd-rise of the ground reaction force's vertical component between the NAFB and the AFO (p < 0.00).

CONCLUSION

Both orthotic interventions could control the ankle-foot complex during the gait and reduce the employment of compensatory gait mechanisms.

Relationship between ankle function and walking ability for children and young adults with cerebral palsy: A systematic review of deficits and targeted interventions

BACKGROUND

A primary goal of treatment for children with cerebral palsy is improved walking ability to allow for a more active and independent lifestyle. With the importance of ankle function to walking ability, and the deficits in ankle function associated with cerebral palsy, there is good rationale for targeting this joint in an effort to improve walking ability for this population.

RESEARCH QUESTION

How do deficits and targeted interventions of the ankle joint influence walking ability in children with cerebral palsy?

METHODS

A specific search criteria was used to identify articles that either (1) provided information on the relationship between ankle function and walking ability or (2) investigated the effect of a targeted ankle intervention on walking ability in cerebral palsy. PubMed, Embase, CINAHL, and Web of Science databases were searched from 1980-April, 2020. Resulting citations were compared against a prospective set of inclusion and exclusion criteria. Data relevant to the original research question was extracted, and the level of evidence for each intervention study was scored. Interpretation was focused on specific, pre-determined mobility measures.

RESULTS

Sixty-one citations met all criteria for data extraction, six of which were observational, and fifty-five of which were interventional. Level of evidence ranged from 2 to 4. Self-selected walking speed was the most common measure of walking ability, while physical activity level was the least common.

SIGNIFICANCE

Ankle function is an important contributor to the walking ability of children with cerebral palsy, and most interventions targeting the ankle seem to demonstrate a benefit on walking ability, but future higher-powered and/or controlled studies are necessary to confirm these findings.

Effect of functional electrical stimulation versus TheraTogs on gait and balance in children with hemiplegic cerebral palsy: a randomized controlled trial

Background

Children with cerebral palsy exhibit postural restrictions and gait problems as a result of both primary and secondary brain damage impairments. One of the main goals of cerebral palsy rehabilitation is to improve gait and balance. As a result, the purpose of this study was to compare the effects of FES and TheraTogs on gait and balance in children with hemiplegic CP. A randomized controlled study was conducted on 30 children with hemiplegic CP (18 boys and 12 girls) between the ages of 8 and 12 years. The children were divided into two equal groups. In addition to the traditional physical treatment program, the FES group received functional electrical stimulation (pulse width 300 μs, frequency 33 Hz, 2 h/day, 3 days/week, 3 months). The TheraTogs group, on the other hand, received the TheraTogs strapping system as well as the same traditional program for the same time period. The 3-D motion analysis and the Biodex balance system were used to analyze gait parameters and postural stability at baseline and 3 months after the intervention.

Results

When comparing the mean values of the gait parameters and postural stability indices of children in both groups before and after treatment, a significant improvement was reported. Furthermore, the FES group showed a greater improvement in all of the measured outcomes (P < 0.001).

Conclusion

Functional electrical stimulation improves gait pattern and postural stability in children with hemiplegic cerebral palsy significantly more than TheraTogs strapping systems.

Clinical trial registration

This study was registered in the ClinicalTrial.gov PRS (NCT05020834).

Effectiveness of an ankle-foot orthosis on walking in patients with stroke: a systematic review and meta-analysis

We conducted a meta-analysis to investigate the effectiveness of ankle–foot orthosis (AFO) use in improving gait biomechanical parameters such as walking speed, mobility, and kinematics in patients with stroke with gait disturbance. We searched the MEDLINE (Medical Literature Analysis and Retrieval System Online), CINAHL (Cumulative Index to Nursing and Allied Health Literature), Cochrane, Embase, and Scopus databases and retrieved studies published until June 2021. Experimental and prospective studies were included that evaluated biomechanics or kinematic parameters with or without AFO in patients with stroke. We analyzed gait biomechanical parameters, including walking speed, mobility, balance, and kinematic variables, in studies involving patients with and without AFO use. The criteria of the Cochrane Handbook for Systematic Reviews of Interventions were used to evaluate the methodological quality of the studies, and the level of evidence was evaluated using the Research Pyramid model. Funnel plot analysis and Egger’s test were performed to confirm publication bias. A total of 19 studies including 434 participants that reported on the immediate or short-term effectiveness of AFO use were included in the analysis. Significant improvements in walking speed (standardized mean difference [SMD], 0.50; 95% CI 0.34–0.66; P < 0.00001; I², 0%), cadence (SMD, 0.42; 95% CI 0.22–0.62; P < 0.0001; I², 0%), step length (SMD, 0.41; 95% CI 0.18–0.63; P = 0.0003; I², 2%), stride length (SMD, 0.43; 95% CI 0.15–0.71; P = 0.003; I², 7%), Timed up-and-go test (SMD, − 0.30; 95% CI − 0.54 to − 0.07; P = 0.01; I², 0%), functional ambulation category (FAC) score (SMD, 1.61; 95% CI 1.19–2.02; P < 0.00001; I², 0%), ankle sagittal plane angle at initial contact (SMD, 0.66; 95% CI 0.34–0.98; P < 0.0001; I², 0%), and knee sagittal plane angle at toe-off (SMD, 0.39; 95% CI 0.04–0.73; P = 0.03; I², 46%) were observed when the patients wore AFOs. Stride time, body sway, and hip sagittal plane angle at toe-off were not significantly improved (p = 0.74, p = 0.07, p = 0.07, respectively). Among these results, the FAC score showed the most significant improvement, and stride time showed the lowest improvement. AFO improves walking speed, cadence, step length, and stride length, particularly in patients with stroke. AFO is considered beneficial in enhancing gait stability and ambulatory ability.