The Utilization of a Gait Pattern Classification System to Investigate the Effects of Ankle–Foot Orthoses on Gait in Children with Cerebral Palsy

Background/Objectives: International guidelines recommend the use of orthoses in subjects with cerebral palsy (CP), even though there is limited evidence of their effectiveness. Little is known about their effectiveness in children and adolescents with other types of neuromotor disability. Methods: The review protocol was recorded on the PROSPERO register (CRD42024509165) and conformed to the PRISMA guidelines. The inclusion criteria were any type of ankle–foot orthoses (AFOs); pediatric subjects with any non-acquired neuromotor disease; any type of outcome measure regarding gait performance; controlled studies; and those in the English language. Screening, selection, risk of bias assessment, and data extraction were performed by a group of independent researchers. Results: Fifty-seven reports were included, with most regarding CP; three involved subjects with Charcot–Marie–Tooth disease or Duchenne dystrophy. Nine were RCTs. A meta-analysis was performed for studies including subjects with CP. The meta-analysis demonstrated the effectiveness of AFOs in increasing stride length (MD −10.21 [−13.92, −6.51]), ankle dorsiflexion at IC (MD 9.66 [7.05, 12.27]), and peak ankle DF in stance (MD 5.72 [2.34, 9.09]) while reducing cadence (MD 0.13 [0.06, 0.17]) and the energy cost of walking (MD −0.02 [−0.03, −0.00]). The peak ankle power generated at push-off was significantly increased with flexible AFOs compared to rigid AFOs (MD 0.38 [0.30, 0.46]), but it decreased with both compared to walking barefoot or with shoes (MD −0.35 [−0.49, −0.22]). Evidence regarding DMD and CMT was limited but suggested opting for individualized flexible AFOs, which preserved peak ankle power generation. Conclusions: AFOs improve gait performance in CP. Flexible AFOs are preferable because they preserve the peak ankle power generated at push-off compared to rigid AFOs.

IntroductionRigid Ankle-Foot Orthoses (AFOs) are commonly prescribed to counteract excessive knee flexion during the stance phase of gait in children with cerebral palsy (CP). While rigid AFOs may normalize knee kinematics and kinetics effectively, it has the disadvantage of impeding push-off power. A spring-like AFO may enhance push-off power, which may come at the cost of reducing the knee flexion less effectively. Optimizing this trade-off between enhancing push-off power and normalizing knee flexion in stance is expected to maximize gait efficiency. This study investigated the effects of varying AFO stiffness on gait biomechanics and efficiency in children with CP who walk with excessive knee flexion in stance. Fifteen children with spastic CP (11 boys, 10±2 years) were prescribed with a ventral shell spring-hinged AFO (vAFO). The hinge was set into a rigid, or spring-like setting, using both a stiff and flexible performance. At baseline (i.e. shoes-only) and for each vAFO, a 3D-gait analysis and 6-minute walk test with breath-gas analysis were performed at comfortable speed. Lower limb joint kinematics and kinetics were calculated. From the 6-minute walk test, walking speed and the net energy cost were determined. A generalized estimation equation (p<0.05) was used to analyze the effects of different conditions. Compared to shoes-only, all vAFOs improved the knee angle and net moment similarly. Ankle power generation and work were preserved only by the spring-like vAFOs. All vAFOs decreased the net energy cost compared to shoes-only, but no differences were found between vAFOs, showing that the effects of spring-like vAFOs to promote push-off power did not lead to greater reductions in walking energy cost. These findings suggest that, in this specific group of children with spastic CP, the vAFO stiffness that maximizes gait efficiency is primarily determined by its effect on knee kinematics and kinetics rather than by its effect on push-off power.Trial RegistrationDutch Trial Register NTR3418

Purpose: Functional electrical stimulation (FES), an assistive device used for foot drop, has been found to improve the speed and energy cost of walking in people with multiple sclerosis (pwMS). This study aims to compare the immediate orthotic effect on walking of two different devices; the Odstock Dropped Foot Stimulator (ODFS) and Walkaide (WA). Method: Twenty pwMS (10 female, 10 male, mean age 50.4 ± 7.3 years) currently using ODFS were recruited. Participants walked for 5 min around an elliptical 9.5 m course at their preferred walking speed; once with ODFS, once with WA and once without FES on the same day of testing. Gait speed, distance and energy cost were measured. Results: There was a statistically significant increase in walking speed for the ODFS (p = 0.043) and a near to significant increase for the WA (p = 0.06) in comparison to without FES. There were no differences between the ODFS and WA in terms of either walking speed (p = 0.596) or energy cost (p = 0.205). Conclusions: This is the first pilot study to compare the effects of two different FES devices on walking. Further research recruiting a larger cohort of FES naive participants is needed.Implications for RehabilitationFunctional electrical stimulation (FES) used for foot drop in multiple sclerosis (MS) is effective in improving the speed of walking.The Odstock Dropped Foot Stimulator and the Walkaide have similar orthotic effects on the speed and energy cost of walking in people with MS.Further research is urgently needed to compare FES devices, recruiting treatment of naive participants for a fully powered RCT.

Passive ankle foot orthoses (AFOs) are often prescribed for children with cerebral palsy (CP) to assist locomotion, but predicting how specific device designs will impact energetic demand during gait remains challenging. Powered AFOs have been shown to reduce energy costs of walking in unimpaired adults more than passive AFOs, but have not been tested in children with CP. The goal of this study was to investigate the potential impact of powered and passive AFOs on muscle demand and recruitment in children with CP and crouch gait. We simulated gait for nine children with crouch gait and three typically-developing children with powered and passive AFOs. For each AFO design, we computed reductions in muscle demand compared to unassisted gait. Powered AFOs reduced muscle demand 15–44% compared to unassisted walking, 1–14% more than passive AFOs. A slower walking speed was associated with smaller reductions in absolute muscle demand for all AFOs (r2 = 0.60–0.70). However, reductions in muscle demand were only moderately correlated with crouch severity (r2 = 0.40–0.43). The ankle plantarflexor muscles were most heavily impacted by the AFOs, with gastrocnemius recruitment decreasing 13–73% and correlating with increasing knee flexor moments (r2 = 0.29–0.91). These findings support the potential use of powered AFOs for children with crouch gait, and highlight how subject-specific kinematics and kinetics may influence muscle demand and recruitment to inform AFO design.

Background: Cerebral palsy (CP) is the most common cause of motor disability in children and can cause severe gait deviations. The sagittal gait patterns classification for children with bilateral CP is an important guideline for the planning of the rehabilitation process. Ankle foot orthoses should improve the biomechanical parameters of pathological gait in the sagittal plane. Methods: A systematic search of the literature was conducted to identify randomized controlled trials (RCT) and controlled clinical trials (CCT) which measured the effect of ankle foot orthoses (AFO) on the gait of children with spastic bilateral CP, with kinetic, kinematic, and functional outcomes. Five databases (Pubmed, Scopus, ISI Web of SCIENCE, SciELO, and Cochrane Library) were searched before February 2020. The PEDro Score was used to assess the methodological quality of the selected studies and alignment with the Cochrane approach was also reviewed. Prospero registration number: CRD42018102670. Results: We included 10 studies considering a total of 285 children with spastic bilateral CP. None of the studies had a PEDro score below 4/10, including five RCTs. We identified five different types of AFO (solid; dynamic; hinged; ground reaction; posterior leaf spring) used across all studies. Only two studies referred to a classification for gait patterns. Across the different outcomes, significant differences were found in walking speed, stride length and cadence, range of motion, ground force reaction and joint moments, as well as functional scores, while wearing AFO. Conclusions: Overall, the use of AFO in children with spastic bilateral CP minimizes the impact of pathological gait, consistently improving some kinematic, kinetic, and spatial-temporal parameters, and making their gait closer to that of typically developing children. Creating a standardized protocol for future studies involving AFO would facilitate the reporting of new scientific data and help clinicians use their clinical reasoning skills to recommend the best AFO for their patients.

In persons with calf muscle weakness, walking energy cost is commonly increased due to persistent knee flexion and a diminished push-off. Provided ankle-foot orthoses (AFOs) usually lower walking energy cost. To maximize the reduction in energy cost, AFO bending stiffness should be individually optimized, but this is not common practice. Therefore, we aimed to evaluate whether individually stiffness-optimized AFOs reduce walking energy cost compared to conventional AFOs in persons with non-spastic calf muscle weakness and, secondarily, whether stiffness-optimized AFOs improve walking speed and gait biomechanics. Thirty-seven persons with non-spastic calf muscle weakness using a conventional AFO were included. Participants were provided a new, individually stiffness-optimized AFO. Walking energy cost, speed and gait biomechanics were assessed, at delivery and 3-months follow-up. Stiffness-optimized AFOs reduced walking energy cost with 9.2% (-0.42J/kg/m, 95%CI: 0.26 to 0.57) compared to the conventional AFOs while walking speed increased with 5.2% (+0.05m/s, 95%CI: 0.03 to 0.08). In bilateral affected persons the effects were larger compared to unilateral affected persons (difference effect energy cost: 0.31J/kg/m, speed: +0.09m/s). Although individually gait biomechanics changed considerably, no significant group differences were found (p > 0.118). We demonstrated that individually stiffness-optimized AFOs considerably and meaningfully reduced walking energy cost compared to conventional AFOs, which was accompanied by an increase in walking speed. Especially in bilateral affected persons large effects of stiffness-optimization were found. The individual differences in gait changes substantiate the recommendation that the AFO bending stiffness should be individually tuned to minimize walking energy cost.

Purpose: A constructivist phenomenological study explored impacts of ankle foot orthoses (AFOs) or functional electrical stimulation (FES) on people with foot-drop from multiple sclerosis (MS). Method: Focus groups following topic guides were analysed using interpretative phenomenological analysis, with researcher reflexivity, participant verification and peer checking of analysis. Participants with sustained use of the devices (under 2 y) were invited from two quantitative studies that (a) investigated immediate FES effects (n = 12) and (b) compared habitual use of AFO (n = 7) or FES (n = 6). Two focus groups addressed AFO (n = 4) and FES (n = 6) experiences. Results: Similar numbers of positive and negative aspects were described for AFO and FES. Both reduced fatigue, improved gait, reduced trips and falls, increased participation, and increased confidence; greater balance/stability was reported for AFOs, and increased walking distance, fitness and physical activity for FES. Barriers to both included avoiding reliance on devices and implications for shoes and clothing; a non-normal gait pattern was reported for AFO, and difficulties of application and limitations in the design of FES. However, participants felt the positives outweighed the negatives. Conclusions: Participants felt benefits outweighed the drawbacks for AFO and FES; greater understanding of user preferences and satisfaction may increase likelihood of usage and efficacy.Implications for RehabilitationInterventions to reduce the impacts of foot-drop in people with multiple sclerosis (MS) are important to optimise physical activity participation and participation in life; they include ankle foot orthoses (AFOs) and functional electrical stimulation (FES).Research is lacking regarding user satisfaction and perceived outcomes, therefore, two separate focus groups were conducted from a constructivist phenomenological perspective to explore the impacts of AFOs (n = 4) and FES (n = 6) on people with foot-drop from MS.Some similar positive aspects of AFO and FES use were described, including reduced fatigue, improved gait and fewer trips and falls, while common barriers included finding the device cumbersome, uncomfortable, and inconvenient, with some psychological barriers to their use.On balance, the impacts of the devices on improving activities and participation were more important for participants than practical barriers, highlighting the importance of combining understanding of individual experiences and preferences with clinical decision-making when prescribing a device to manage foot-drop.

Purpose: This exploratory trial investigated the effects of rigid ankle foot orthoses (AFO) with an optimally cast Angle of the Ankle in the AFO (AAAFO) on the gait of children with Cerebral Palsy (CP), and whether tuning of the AFO – Footwear Combination (AFO-FC) further affected gait. Methods: Eight children with CP underwent gait analysis and tuning of their AFO-FCs using a 3-D motion analysis system. Comparisons were carried out for selected gait parameters between three conditions – barefoot, non-tuned AFO-FC and tuned AFO-FC. Results: In comparison to barefoot gait, walking with a non-tuned AFO-FC produced significant (p < 0.05) improvements in several key gait parameters. Compared to the non-tuned AFO-FC, on average a tuned AFO-FC produced a significant reduction in peak knee extension and knee ROM during gait. However, when examined as case studies, it was observed that the type of gait pattern demonstrated while wearing a non-tuned AFO-FC affected the outcomes of tuning. Conclusions: The findings of the current study indicate the potential benefits of using rigid AFO-FC with optimal AAAFO and tuning of AFO-FCs. This study emphasises the need for categorising children with CP based on their gait patterns when investigating the effects of interventions such as AFOs.Implications for RehabilitationRigid ankle foot orthoses (AFO) cast at an optimal angle to accommodate the length of gastrocnemius muscle may positively influence walking in children with Cerebral Palsy (CP).Tuning of the AFO-Footwear Combination (AFO-FC) has potential benefits to the walking of children with CP, depending on their gait abnormalities.When investigating the effects of interventions such as AFOs, it is important to categorise children with CP based on their gait abnormalities.

Spring-like Ankle Foot Orthoses reduce the energy cost of walking by taking over ankle work

ObjectiveImpaired ankle dorsiflexion in hemiparesis may be treated with ankle-foot orthosis or functional electrical stimulation. Semi-implanted selective functional electrical stimulation uses independent stimulations of deep and superficial peroneal nerves. The aim of this study was to compare gait kinematics using ankle-foot orthosis or semi-implanted selective functional electrical stimulation over 6 months in hemiparesis.MethodsSubjects with chronic hemiparesis, randomized into ankle-foot orthosis or semi-implanted selective functional electrical stimulation groups, underwent comfortable gait analysis without and with device OFF and ON, before, and 3 and 6 months after treatment onset. The effects of condition, visit and group on gait kinematics (analysis of variance; ANOVA) were analysed.ResultsA total of 27 subjects were included (ankle-foot orthosis, n = 13; semi-implanted selective functional electrical stimulation, n = 14). The only between-group difference in changes from OFF to ON conditions was a deteriorated ankle dorsiflexion speed with ankle-foot orthosis at month 6 (condition*group, p = 0.04; ankle-foot orthosis, –60%, p = 0.02; semi-implanted selective functional electrical stimulation, non significant). Both groups pooled, from OFF to ON gait speed (+ 0.07 m/s; + 10%), cadence (+ 4%), step length (+ 6%) and peak ankle dorsiflexion (+ 6°) increased, and peak ankle inversion (–5°) and peak knee flexion (–2°) decreased (p < 0.001); finally, peak knee flexion in the OFF condition increased (+ 2°, p = 0.03).ConclusionSemi-implanted selective functional electrical stimulation and ankle-foot orthosis similarly impacted gait kinematics in chronic hemiparesis after 6 months of use. Ankle dorsiflexion speed in swing deteriorated markedly with ankle-foot orthosis.LAY ABSTRACTAfter a central nervous system injury, walking disorders are associated with ankle dorsiflexion and foot eversion in the paretic limb during the swing phase. Movement of the ankle can be partially corrected with ankle-foot orthosis (AFO) or functional electrical stimulation (FES). The semi-implanted selective FES (SIS-FES) is an advanced FES device using independent stimulations of deep and superficial peroneal nerves, to separately control movements of ankle dorsiflexion, hallucis extension and foot eversion, and to optimize FES-associated walking improvements. This study compared walking using AFO or SIS-FES over 6 months in hemiparesis. A total of 27 patients with chronic hemiparesis, randomized into AFO or SIS-FES groups, underwent comfortable walking analysis without and with device OFF and ON, before, and 3 and 6 months after treatment onset. SIS-FES and AFO similarly improved walking speed, cadence, step length, ankle dorsiflexion and foot eversion, while ankle dorsiflexion speed in swing markedly deteriorated with AFO.

The aim of this study was to assess the functional effects and mechanical contribution of Ankle Foot Orthoses (AFO) prescribed to overcome drop-foot gait. We hypothesized that poor functional effects of the AFO relate to insufficient mechanical contribution of the AFO during the swing phase, or unwanted constraining of the ankle during the stance phase. In seven patients with Stroke or Multiple Sclerosis, we determined changes in energy cost of walking resulting from wearing an AFO, as a measure of the functional effects. In addition, an instrumented gait analysis was performed, and the mechanical AFO properties were measured, to calculate the mechanical contribution of the AFO. The AFO was sufficiently stiff to effectively support the foot in swing, without hampering the ankle during stance. For the whole group, there was a significant improvement in walking speed and energy cost (12%). However, the AFO had no functional benefit in terms of a reduced energy cost of walking for three patients, who coherently demonstrated no pathological plantar flexion during swing without their AFO. We conclude that functional benefit from the AFO was only found when the mechanical AFO characteristics met the need to support the patients' mechanical deficiencies.

To maximize effects of dorsal leaf ankle foot orthoses (AFOs) on gait in people with bilateral plantarflexor weakness, the AFO properties should be matched to the individual. However, how AFO properties interact regarding their effect on gait function is unknown. We studied the interaction of AFO bending stiffness with neutral angle and footplate stiffness on the effect of bending stiffness on walking energy cost, gait kinematics and kinetics in people with plantarflexor weakness by employing predictive simulations.Our simulation framework consisted of a planar 11 degrees of freedom model, containing 11 muscles activated by a reflex-based neuromuscular controller. The controller was optimized by a comprehensive cost function, predominantly minimizing walking energy cost. The AFO bending and footplate stiffness were modelled as torsional springs around the ankle and metatarsal joint. The neutral angle of the AFO was defined as the angle in the sagittal plane at which the moment of the ankle torsional spring was zero. Simulations without AFO and with AFO for 9 bending stiffnesses (0–14 Nm/degree), 3 neutral angles (0–3-6 degrees dorsiflexion) and 3 footplate stiffnesses (0–0.5–2.0 Nm/degree) were performed.When changing neutral angle towards dorsiflexion, a higher AFO bending stiffness minimized energy cost of walking and normalized joint kinematics and kinetics. Footplate stiffness mainly affected MTP joint kinematics and kinetics, while no systematic and only marginal effects on energy cost were found.In conclusion, the interaction of the AFO bending stiffness and neutral angle in bilateral plantarflexor weakness, suggests that these should both be considered together when matching AFO properties to the individual patient.

Ankle foot orthosis (AFO) are commonly prescribed for correcting crouch gait in children with cerebral palsy (CP). There are multiple AFO variants and selecting an optimal AFO for CP subject is often challenging. In this work, we have analyzed the effect of two passive AFO, naming Ground reaction AFO (GRAFO) and Leaf spring AFO (LSAFO) on varying severity of crouch gait in a musculoskeletal simulation environment. Impact of GRAFO and LSAFO on muscle loading and recruitment, in terms of muscle 'impulse', 'yank' and 'coactivation' was investigated for children with crouch gait along with normal gait of typically developing children. Simulation results show increased activation of the dorsiflexor muscles, indicating better ankle control and a net reduction in ankle coactivation for both types of AFO. Compared to GRAFO, LSAFO produced lower energetic cost of walking. The simulation pipeline enables to quantify the effect of different AFO configuration on muscle behavior and recruitment, and can be used to design personalized AFO as per subject-specific gait dynamics.

The influence of ankle-foot orthoses on gait pathology in children with cerebral palsy: A retrospective study

Children with spastic cerebral palsy show varied gait patterns and muscle morphological alterations. We explored gastrocnemius medialis behavior during gait in typically developing children and children with cerebral palsy across different gait patterns. Eighteen children with spasticity of the leg muscles (female: 8, age: 11.1±3.3 y) with a diagnosis of cerebral palsy (n=17) or hereditary spastic paraplegia (n=1) and 16 typically developing children (female: 11, age: 11.2±3.2 y) walked on an instrumented treadmill. Three distinct gait patterns were determined in children with cerebral palsy. Muscle-tendon unit, fascicle, belly, and tendon behavior were assessed with dynamic ultrasound imaging. Unpaired statistical non-parametric mapping (SnPM) t-tests and Mann-Whitney U tests assessed differences between children with cerebral palsy and typically developing children. One-way ANOVA SnPM tests and Kruskall-Wallis tests assessed differences across gait patterns. Tendon lengthening in the first half of stance was higher in children with cerebral palsy compared to typically developing children (Δ6.6mm), yet total tendon lengthening in stance (Δ5.3mm) and fascicle shortening during push-off were decreased (Δ6.2mm). Children with cerebral palsy displaying a mildly affected kinematic gait pattern showed pathological muscle belly lengthening in stance (Δ5.7mm), while children with equinus (Δ6.4mm) or crouch gait (Δ6.0mm) showed reduced tendon lengthening. Efficient gastrocnemius medialis behavior is compromised in children with spastic cerebral palsy. Children with mildly affected gait show the most deviation in muscular components involved in active force generation, while those with equinus and crouch gait also show deviations in tendinous components. Interventions aimed at improving gait should consider this aberrant behavior.