Commonly Used Types and Recent Development of Ankle-Foot Orthosis: A Narrative Review

Ankle-foot orthoses for improving walking in adults with calf muscle weakness due to neuromuscular disorders

BACKGROUND

Calf muscle weakness is a common symptom in slowly progressive neuromuscular disorders that lead to walking problems like instability and increased walking effort. The mainstay of treatment to improve walking in this population is the provision of ankle-foot-orthoses (AFOs). Since we are not aware of an up-to-date and complete overview of the effects of AFOs used for calf muscle weakness in slowly progressive neuromuscular disorders, we reviewed the evidence for the effectiveness of AFOs to improve walking in this patient group, in order to support clinical decision-making.

OBJECTIVES

To review the evidence for the effects of ankle-foot orthoses (AFOs) for improving walking in adults with calf muscle weakness due to slowly progressive neuromuscular disorders.

SEARCH METHODS

On 10 February 2023, we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, Embase, MEDLINE, ClinicalTrials.gov, and WHO ICTRP.

SELECTION CRITERIA

We looked for randomised controlled trials (RCTs), including randomised cross-over studies and quasi-RCTs, and non-randomised studies (NRSs) that examined the effects of AFO interventions compared with shoes-only walking in adults with calf muscle weakness due to neuromuscular disorders.

DATA COLLECTION AND ANALYSIS

We used the methodological procedures described in the Cochrane Handbook for Systematic Reviews of Interventions. We summarised findings for the primary outcome (objectively measured walking effort, assessed as walking energy cost) and secondary outcomes (perceived walking effort, physical mobility, gait parameters, AFO use, satisfaction with the AFO, and adverse events). We grouped results according to the type of AFO material and synthesised them in meta-analysis where possible. We used the GRADE approach to rate the certainty of the evidence.

MAIN RESULTS

We included four randomised cross-over studies and six NRSs with 186 participants in total (the smallest study had 8 participants and the largest had 37). All studies were designed as self-controlled studies and examined the effects of custom-made and/or prefabricated AFOs. The AFOs were made of carbon (5 studies), polypropylene (5 studies), silicone (1 study), metal (1 study), elastic materials (2 studies), or leather combined with other materials (1 study). Outcome measures with AFOs were assessed during a single session (in some studies, people already used the study AFO in daily life), when the AFO was delivered, or at three-week or three-month follow-up. We judged one study to be at moderate risk of bias, and nine studies to be at high or serious risk of bias, primarily due to bias arising from period and carryover effects, selection bias, the inability to blind participants and assessors, missing data, and selective reporting. We found that carbon AFOs may reduce walking energy cost (mean difference (MD) -0.86 J/kg/m, 95% confidence interval (CI) -1.33 to -0.39; 2 studies, 45 participants; low-certainty evidence), and may increase walking speed (MD 0.19 m/s, 95% CI 0.11 to 0.27; 4 studies, 71 participants; low-certainty evidence) compared to shoes-only walking. We found that leather AFOs may increase walking speed (MD 0.25 m/s, 95% CI 0.07 to 0.43; 1 study, 11 participants; low-certainty evidence). Little or no effect on walking speed was found with polypropylene AFOs (MD 0.00 m/s, 95% CI -0.11 to 0.11; 2 studies, 25 participants; low-certainty evidence) and elastic AFOs (MD 0.03 m/s, 95% CI -0.12 to 0.18; 1 study, 14 participants; low-certainty evidence). Carbon AFOs may also enhance satisfaction while walking (1 study, 16 participants; low-certainty evidence). We were unable to draw conclusions about perceived walking effort (one study, 8 participants), balance (two studies, 21 participants), and AFO use (two studies, 51 participants), as the evidence is very uncertain. Finally, two studies (45 participants) reported on adverse events (low-certainty evidence).

AUTHORS' CONCLUSIONS

The available evidence for ankle-foot orthoses (AFOs) to improve walking in adults with calf muscle weakness comes from a limited number of small studies with heterogeneity in intervention characteristics and outcome assessment, and is of low to very low certainty. The evidence suggests that carbon AFOs may reduce walking energy cost (effort), increase walking speed, and enhance satisfaction, and leather AFOs may increase walking speed, while polypropylene and elastic AFOs may make little or no difference to walking speed. We are unable to draw conclusions about the effects of AFOs on perceived walking effort, balance, and use. Nor can we draw conclusions about adverse effects of using AFOs. The variety in the findings for AFOs made of different materials suggests further investigation is warranted to explore how different AFO materials impact walking improvement in people with calf muscle weakness due to slowly progressive neuromuscular disorders.

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.

The Impact of Low-Level Laser Therapy on Spasticity in Children with Spastic Cerebral Palsy: A Systematic Review

CONTEXT

Spastic cerebral palsy (SCP) is a condition characterized by muscle stiffness and involuntary movements, which greatly affect movement abilities and overall well-being. Low-level laser therapy (LLLT) has emerged as a treatment option for managing spasticity, though the current evidence varies.

OBJECTIVE

This systematic review seeks to assess the efficacy of LLLT on spasticity in children with cerebral palsy. We hope it will pinpoint areas where more research is needed and suggest directions for future studies.

METHOD

A search of the literature was performed across databases, such as PubMed, Google Scholar, Scopus, and Elicit. The search utilized keywords and the Medical Subject Headings (MeSH) terms. Only studies conducted in English that focused on children with cerebral palsy (CP) and explored the effects of LLLT on spasticity were considered. The quality of the selected studies was evaluated using assessment tools.

RESULTS

The search identified 534 references, out of which eight studies met the screening criteria for inclusion. All cited papers indicated reductions in spasticity with further mention of reduced pain and greater muscle strength by some authors.

CONCLUSIONS

This review indicates that LLLT shows promise in decreasing spasticity in children with cerebral palsy. Nevertheless, a lack of treatment parameters, heterogeneity in research methods, and a lack of objective outcome measures weaken the results. This review underscores the importance of standardized procedures and carefully planned randomized controlled trials to establish conclusive findings on the effectiveness of LLLT in this population.

Deep Learning and IoT-Based Ankle-Foot Orthosis for Enhanced Gait Optimization

BACKGROUND/OBJECTIVES

This paper proposes a method for managing gait imbalances by integrating the Internet of Things (IoT) and machine learning technologies. Ankle-foot orthosis (AFO) devices are crucial medical braces that align the lower leg, ankle, and foot, offering essential support for individuals with gait imbalances by assisting weak or paralyzed muscles. This research aims to revolutionize medical orthotics through IoT and machine learning, providing a sophisticated solution for managing gait issues and enhancing patient care with personalized, data-driven insights.

METHODS

The smart ankle-foot orthosis (AFO) is equipped with a surface electromyography (sEMG) sensor to measure muscle activity and an Inertial Measurement Unit (IMU) sensor to monitor gait movements. Data from these sensors are transmitted to the cloud via fog computing for analysis, aiming to identify distinct walking phases, whether normal or aberrant. This involves preprocessing the data and analyzing it using various machine learning methods, such as Random Forest, Decision Tree, Support Vector Machine (SVM), Artificial Neural Network (ANN), Long Short-Term Memory (LSTM), and Transformer models.

RESULTS

The Transformer model demonstrates exceptional performance in classifying walking phases based on sensor data, achieving an accuracy of 98.97%. With this preprocessed data, the model can accurately predict and measure improvements in patients' walking patterns, highlighting its effectiveness in distinguishing between normal and aberrant phases during gait analysis.

CONCLUSIONS

These predictive capabilities enable tailored recommendations regarding the duration and intensity of ankle-foot orthosis (AFO) usage based on individual recovery needs. The analysis results are sent to the physician's device for validation and regular monitoring. Upon approval, the comprehensive report is made accessible to the patient, ensuring continuous progress tracking and timely adjustments to the treatment plan.

Three-dimensional printed exoskeletons and orthoses for the upper limb-A systematic review

This systematic review aims to assess and summarize the current landscape in exoskeletons and orthotic solutions developed for upper limb medical assistance, which are partly or fully produced using 3-dimensional printing technologies and contain at least the elbow or the shoulder joints. The initial search was conducted on Web of Science, PubMed, and IEEEXplore, resulting in 92 papers, which were reduced to 72 after removal of duplicates. From the application of the inclusion and exclusion criteria and selection questionnaire, 33 papers were included in the review, being divided according to the analyzed joints. The analysis of the selected papers allowed for the identification of different solutions that vary in terms of their target application, actuation type, 3-dimensional printing techniques, and material selection, among others. The results show that there has been far more research on the elbow joint than on the shoulder joint, which can be explained by the relative complexity of the latter. Moreover, the findings of this study also indicate that there is still a gap between the research conducted on these devices and their practical use in real-world conditions. Based on current trends, it is anticipated that the future of 3-dimensional printed exoskeletons will revolve around the use of flexible and high-performance materials, coupled with actuated devices. These advances have the potential to replace the conventional fabrication methods of exoskeletons with technologies based on additive manufacturing.

Vacuum Chamber Infusion for Fiber-Reinforced Composites

A new approach to an automatable fiber impregnation and consolidation process for the manufacturing of fiber-reinforced composite parts is presented in this article. Therefore, a vacuum chamber sealing machine classically used in food packaging is modified for this approach-Vacuum Chamber Infusion (VCI). Dry fiber placement (DFP) preforms, made from 30 k carbon fiber tape, with different layer amounts and fiber orientations, are infused with the VCI and with the state-of-the-art process-Vacuum Assisted Process (VAP)-as the reference. VCI uses a closed system that is evacuated once, while VAP uses a permanently evacuated open system. Since process management greatly influences material properties, the mechanical properties, void content, and fiber volume fraction (FVF) are analyzed. In addition, the study aims to identify how the complexity of a resin infusion process can be reduced, the automation potential can be increased, and the number of consumables can be reduced. Comparable material characteristics and a reduction in consumables, setup complexity, and manufacturing time by a factor of four could be approved for VCI. A void content of less than 2% is measured for both processes and an FVF of 39% for VCI and 45% for VAP is achieved.

Articulated ankle-foot orthoses associated with home-based task-specific training improve functional mobility in patients with stroke: a randomized clinical trial

INTRODUCTION

We compared fixed and articulated ankle-foot orthoses (AFOs) in home-based mobility tasks to assess short-term mobility, dynamic balance, quality of life, anxiety/depression, disability level, stroke severity, autonomy, human functioning, and patient satisfaction.

METHODS

This was a two-arm, parallel-group, randomized controlled trial with concealed allocation, assessor blinding, and a complete case analysis involving patients with chronic stroke. The participants were randomized into two groups: fixed (n = 24) and articulated (n = 23) AFOs. The AFOs were custom-fabricated, and both groups performed four-week home-based mobility tasks five days weekly. Primary outcome measures included changes in balance and mobility assessed using the Tinetti Performance-Oriented Mobility Assessment (POMA), Timed Up and Go (TUG) test, and Functional Ambulation Category (FAC). Secondary outcomes included quality of life, anxiety/depression, disability, stroke severity, autonomy, human functioning, and patient satisfaction.

RESULTS

In a between-group comparison, after adjusting for age, sex, stroke severity, and thrombolysis, the articulated AFO group showed better performance in the TUG test (p = 0.020; d = 0.93), POMA-Gait (p = 0.001; d = 0.53), POMA-Total (p = 0.048; d = 0.98), and FAC (p = 0.003; d = 1.03) than the fixed AFO group. Moreover, significant difference was noted in human functioning (moving around using equipment)between the groups (p = 0.047; d = 92).

CONCLUSION

A program involving home-based mobility tasks and articulated AFOs improved functional mobility after stroke.

Differential Diagnosis of "Foot Drop": Implications for Peripheral Nerve Surgery

BACKGROUND

 At least 128,000 patients in the United States each year suffer from foot drop. This is a debilitating condition, marked by the inability to dorsiflex and/or evert the affected ankle. Such patients are rendered to a lifetime of relying on an ankle-foot orthosis (AFO) for walking and nighttime to prevent an equinovarus contracture.

METHODS

 This narrative review explores the differential diagnosis of foot drop, with a particular focus on clinical presentation and recovery, whether spontaneously or through surgery.

RESULTS

 Contrary to popular belief, foot drop can be caused by more than just insult to the common peroneal nerve at the fibular head (fibular tunnel). It is a common endpoint for a diverse spectrum of nerve injuries, which may explain its relatively high prevalence. From proximal to distal, these conditions include lumbar spine nerve root damage, sciatic nerve palsy at the sciatic notch, and common peroneal nerve injury at the fibular head. Each nerve condition is marked by a unique clinical presentation, frequency, likelihood for spontaneous recovery, and cadre of peripheral nerve techniques.

CONCLUSION

 The ideal surgical technique for treating foot drop, other than neurolysis for compression, remains elusive as traditional peripheral nerve procedures have been marred by a wide spectrum of functional results. Based on a careful understanding of why past techniques have achieved limited success, we can formulate a working set of principles to help guide surgical innovation moving forward, such as fascicular nerve transfer.

Effects of carbon versus plastic ankle foot orthoses on gait outcomes and energy cost in patients with chronic stroke

OBJECTIVE

To compare the walking performances of hemiplegic subjects with chronic stroke under 3 conditions: with a new standard carbon fibre ankle foot orthosis (C-AFO), with a personal custom-made plastic AFO (P-AFO), and without any orthosis (No-AFO).

DESIGN

Randomized, controlled crossover design.

PATIENTS

Fifteen chronic patients with stroke (3 women  and 12 men, 59 [10] years, 13 [15] years since injury).

METHODS

Patients performed 3 randomized sessions (with C-AFO, P-AFO, no-AFO), consisting of a 6-min walk test (6MWT) with VO2 measurement and a clinical gait analysis. Energy cost (Cw), walking speed, spatio-temporal, kinetic, and kinematic variables were measured.

RESULTS

No significant differences were found between the C-AFO and P-AFO conditions. Distance and walking speed in the 6MWT increased by 12% and 10% (p < 0.001) and stride width decreased by -8.7% and -13% (p < 0.0001) with P-AFO and C-AFO compared with the No-AFO condition. Cw decreased by 15% (p < 0.002), stride length increased by 10% (p < 0.01), step length on affected leg increased by 8% (p < 0.01), step length on contralateral leg by 13% (p < 0.01), and swing time on the contralateral leg increased by 6% (p < 0.01) with both AFO compared with the No-AFO condition.

CONCLUSION

The use of an off-the-shelf composite AFO (after a short habituation period) in patients with chronic stroke immediately improved energy cost and gait outcomes to the same extent as their usual custom-made AFO.

Approach to gait disorders and orthotic management in adult onset neuromuscular diseases

In order to understand abnormal gait, this article will first review normal gait, discuss how neuromuscular diseases disturb gait patterns and review orthotic interventions. In normal gait, concentric contractions accelerate and eccentric contractions decelerate the limb. Neuromuscular gait disorders can be grouped into (1) proximal weakness, (2) distal weakness, (3) nonlength-dependent or generalized weakness, (4) asymmetric weakness, and (5) sensory disorders. Identification of gait disturbance type in neuromuscular diseases leads to the appropriate orthotic prescription since orthotic strategies are grouped into (1) proximal weakness, (2) distal weakness, and (3) sensory disturbances. Orthotics is not indicated in all types of gait disturbance. Weakness in proximal hip musculature can be managed with gait aids such as walkers. In contrast, distal muscle weakness can be managed with orthotics. Preservation of gait assists in maintenance of daily function and integration in society.

Efficacy of hinged and carbon fiber ankle-foot orthoses in children with unilateral spastic cerebral palsy and drop-foot gait pattern

BACKGROUND

In children with unilateral spastic cerebral palsy (USCP), ankle-foot orthoses (AFOs) are widely used to correct common gait deviations such as a drop-foot pattern. Most studies on this topic have investigated specific time points while omitting other parts of the gait cycle.

OBJECTIVES

This study investigated the separate effects of prefabricated carbon fiber AFOs and custom-made hinged AFOs compared with barefoot walking in children with USCP with a drop-foot gait pattern using statistical parametric mapping.

STUDY DESIGN

Retrospective, cross-sectional, repeated measures study.

METHODS

Twenty ambulatory children (9.9 ± 2.5 years) with USCP and a drop-foot gait pattern were included. Kinematics, kinetics, and spatiotemporal parameters assessed during 3-dimensional gait analysis were compared between barefoot and AFO walking. Statistical parametric mapping was used to compare joint angles and moment waveforms. Kinematics, kinetics and spatiotemporal parameters assessed during 3-dimensional gait analysis were compared between barefoot and AFO walking for each AFO type but not between the 2 AFO types.

RESULTS

Compared with barefoot walking, there was a steeper sole angle at initial contact, corresponding to a heel strike pattern, and an increased ankle dorsiflexion in swing with the use of both AFOs. The ankle plantar flexion moment during loading response increased. Ankle power generation during pre-swing decreased in the carbon fiber AFO group when walking with AFOs.

CONCLUSIONS

Both AFOs were beneficial for improving a drop-foot gait pattern in these small patient groups and can, therefore, be recommended to treat this gait deviation in patients with unilateral cerebral palsy. However, the reduction in ankle power generation during push-off and additional goals targeted by AFOs, such as correction of structural or flexible foot deformities, should be considered for prescription.

Selective orthotic constraint of lower limb movement during walking reveals new insights into neuromuscular adaptation

Introduction

A concern expressed by the clinical community is that the constraint of motion provided by an ankle foot orthosis (AFO) may lead the user to become dependent on its stiffness, leading to learned non-use. To examine this, we hypothesized that using an experimental AFO-footwear combination (exAFO-FC) that constrains ankle motion during walking would result in reduced soleus and tibialis anterior EMG compared to free (exAFO-FC) and control (no AFO, footwear only) conditions.

Method

A total of 14 healthy subjects walked at their preferred speed (1.34 ± 0.09 m·s-1) for 15 min, in three conditions, namely, control, free, and stop.

Results

During the stance phase of walking in the stop condition, ipsilateral soleus integrated EMG (iEMG) declined linearly, culminating in a 32.1% reduction compared to the control condition in the final 5 min interval of the protocol. In contrast, ipsilateral tibialis anterior iEMG declined in a variable fashion culminating in an 11.2% reduction compared to control in the final 5 min interval. During the swing phase, the tibialis anterior iEMG increased by 6.6% compared to the control condition during the final 5 min interval. The contralateral soleus and tibialis anterior exhibited increased iEMG in the stop condition.

Discussion

An AFO-FC functions as a biomechanical motion control device that influences the neural control system and alters the output of muscles experiencing constraints of motion.

Foot offloading associated with carbon fiber orthosis use: A pilot study

BACKGROUND

Traumatic lower limb injuries can result in chronic pain. Orthotic interventions are a leading conservative approach to reduce pain, manage loading, and protect the foot. Robust carbon fiber custom dynamic orthoses (CDOs) designed for military service members have been shown to reduce foot loading. However, the effect of carbon fiber orthosis design, including designs widely used in the civilian sector, on foot loading is unknown.

RESEARCH QUESTION

Determine if carbon fiber orthoses alter foot loading during gait.

METHODS

Loadsol insoles were used to measure peak forces and force impulse acting on the forefoot, midfoot, hindfoot, and total foot. Nine healthy, able-bodied individuals participated. Force impulse was quantified as cumulative loading throughout stance phase. Participants walked without an orthosis and with three carbon fiber orthoses of differing designs: a Firm stiffness CDO, a Moderate stiffness CDO, and a medial and lateral strut orthosis (MLSO).

RESULTS

There were significant main effects of orthosis condition on peak forefoot forces as well as forefoot and hindfoot force impulse. Peak forefoot forces were significantly lower in the Moderate and Firm CDOs compared to no orthosis and MLSO. Compared to walking without an orthosis, forefoot force impulse was significantly lower and hindfoot force impulse was significantly greater in all carbon fiber orthoses. Additionally, hindfoot force impulse in the Firm CDO was significantly higher than in the MLSO and Moderate CDO.

SIGNIFICANCE

The three carbon fiber orthosis designs differed regarding foot loading, with more robust orthoses providing greater forefoot offloading. Orthosis-related changes in forefoot loading suggest that carbon fiber orthoses could reduce loading-associated pain during gait. However, increased hindfoot force impulse suggests caution should be used when considering carbon fiber orthoses for individuals at risk of skin breakdown with repetitive loading.

Foot drop in critically ill patients: a narrative review of an elusive complication with intricate implications for recovery and rehabilitation

Foot drop is a condition characterized by the inability to lift the foot upwards towards the shin bone. This condition may affect a proportion of critically ill patients, impacting on their recovery after the acute phase of the illness. The occurrence of foot drop in critical care patients may result from various underlying causes, including neurological injuries, muscular dysfunction, nerve compression, or vascular compromise. Understanding the etiology and assessing the severity of foot drop in these patients is essential for implementing appropriate management strategies and ensuring better patient outcomes. In this comprehensive review, we explore the complexities of foot drop in critically ill patients. We search for the potential risk factors that contribute to its development during critical illness, the impact it has on patients' functional abilities, and the various diagnostic techniques adopted to evaluate its severity. Additionally, we discuss current treatment approaches, rehabilitation strategies, and preventive measures to mitigate the adverse effects of foot drop in the critical care setting. Furthermore, we explore the roles of critical care physical therapists, neurologists, and other healthcare professionals in the comprehensive care of patients with foot drop syndrome and in such highlighting the importance of a multidisciplinary approach.

A quantitative analysis of optimum design for rigid ankle foot orthoses: The effect of thickness and reinforcement design on stiffness

BACKGROUND

An ankle foot orthosis (AFO) which is prescribed to be rigid should only deform a small amount to achieve its clinical goals. Material thickness and the design of reinforcing features can significantly affect AFO rigidity, but their selection remains based on anecdotal evidence.

OBJECTIVES

To quantify the effect of these parameters on AFO stiffness and to set the basis for quantitative guidelines for the design optimisation of rigid AFOs.

STUDY DESIGN

Experimental and computational study.

METHODS

A polypropylene AFO was produced according to UK standard practice and its stiffness was experimentally measured for 30Nm of dorsiflexion. Its geometry and mechanical characteristics were utilised to create a finite element (FE) model of a typical AFO prescribed to be rigid. Following validation, the model was used to quantify the effect of material thickness and reinforcement design (i.e., reinforcement placement, length) on stiffness. A final set of AFO samples was produced to experimentally confirm key findings.

RESULTS AND CONCLUSIONS

For a specific AFO geometry and loading magnitude, there is a thickness threshold below which the AFO cannot effectively resist flexion and buckles. FE modelling showed that stiffness is maximised when reinforcements are placed at the anterior-most position possible. This key finding was also experimentally confirmed. The stiffness of an AFO reinforced according to standard practice with lateral and medial ribbing was 4.4 ± 0.1 Nm/degree. Instructing the orthotic technician to move the ribbings anteriorly increased stiffness by 22%. Further stiffening is achieved by ensuring the reinforcements extend from the footplate to at least two-thirds of the AFO's total height.

Comparison between prefabricated ankle-foot orthoses, Dyna Ankle and UD Flex, in patients with hemiplegia

OBJECTIVE

To compare the kinematic effects of two widely-used prefabricated ankle-foot orthoses (AFOs), the Dyna Ankle (DA) and UD Flex (UD), on the gait cycle of patients with hemiplegia due to cerebral palsy or acquired brain injury.

METHODS

This was a retrospective cohort study involving 29 patients. Gait analysis results were assessed under three conditions: barefoot, with the DA, and with the UD. Friedman tests and post hoc analysis with Bonferroni correction were performed to assess differences between the three conditions.

RESULTS

The DA significantly improved ankle dorsiflexion during the mid-swing phase, making it more effective in correcting foot drop compared with the UD (DA: 2.28°, UD: 0.44°). Conversely, the UD was more effective in preventing knee flexion during the loading response (DA: 28.11°, UD: 26.72°).

CONCLUSIONS

The DA improved ankle dorsiflexion during the swing phase significantly more than that with the UD in patients with hemiplegia. Compared with the DA, the UD more effectively prevented increased knee flexion during the loading response. The choice to prescribe these orthoses should consider individual patient characteristics.

Functional evaluation of a novel fibreglass-reinforced polyamide custom dynamic AFO for foot drop patients: A pilot study

BACKGROUND

Ankle-foot orthoses (AFOs) are orthopaedic devices often prescribed to treat foot drop. For patients who are not satisfied with off-the-shelf solutions, custom AFOs personalized to the patient's lower limb anatomy are required. Dynamic AFOs provide stability while allowing for physiological ankle mobility in the stance phase of walking.

RESEARCH QUESTION

Can a morphology-based dynamic custom AFO made of fiberglass-reinforced polyamide restore a quasi-normal gait pattern and improve comfort in patients with foot drop?

METHODS

In this pilot study, the legs and feet of ten foot drop patients (age=64.9 ± 11.4 years; BMI=26.2 ± 2.1 kg/m2) were scanned using a Kinect-based 3D scanner. A custom AFO was designed and produced for each patient using a fiberglass-reinforced polyamide through selective laser sintering. To assess kinematics, skin markers were placed on relevant bony landmarks according to a validated protocol. Each patient was instructed to walk at a self-selected comfortable speed under three conditions: wearing the custom AFO, wearing an off-the-shelf orthosis (Codivilla spring), and without any AFO (shod condition). Muscle activation in the tibialis anterior, gastrocnemius, rectus femoris and biceps femoris muscles in both legs was recorded using wireless sEMG sensors. The comfort and of each AFO was evaluated using a Visual Analogue Scale.

RESULTS

The custom AFO resulted in significant increase of stride length and walking speed compared to the shod condition. Except for the hip joint, which exhibited greater maximum flexion and reduced range of motion, the kinematic parameters of all other joints were similar to those observed in a healthy control population. Furthermore, the custom AFO received significantly higher comfort scores compared to the Codivilla spring.

SIGNIFICANCE

This study has provided evidence supporting the effectiveness of custom orthotic solutions in restoring lower limb kinematics and improving the perceived comfort in foot drop patients compared to off-the-shelf solutions.

Effects of Ankle Orthoses, Taping, and Insoles on Postural Stability of Individuals with Chronic Ankle Instability: A Systematic Review

Chronic ankle instability (CAI) is a prevalent condition characterized by recurring instances of the ankle giving way and persistent symptoms, including pain and diminished function. Foot and ankle external supports are commonly used in clinical practice and research for treating CAI. This systematic review aimed to assess the effects of foot and ankle external supports on the postural stability of individuals with CAI to guide clinical practice and inform future research. A comprehensive search was conducted in PubMed, Web of Science, Scopus, and Google Scholar databases from 1 January 2012 to 1 November 2022. Eighteen studies involving individuals with CAI were chosen in this systematic review. The quality of the included studies and risk of bias were assessed using Cochrane Collaboration's tool for randomized controlled trials, the Newcastle-Ottawa Scale for case-control studies, and the DELPHl-list for crossover trial studies. The external supports included in this review were ankle orthoses (elastic, semi-rigid, and active orthoses), taping (kinesiotaping and fibular reposition taping), and insoles (textured and supportive insoles). The outcome measures included static and dynamic postural stability tests, such as the single-leg stance test, star excursion balance test, Y-balance test, single-leg landing test, lateral jump test, walking test, and running test. The results showed that elastic orthoses, Kinesiotaping, and textured insoles demonstrated potential benefits in improving postural stability in individuals with CAI. Elastic orthoses decreased ankle joint motion variability, kinesiotaping facilitated cutaneous receptors and proprioceptive feedback, while textured insoles increased tactile stimulation and foot position awareness. However, the effects of semi-rigid orthoses, fibular reposition taping, and arch support insoles were inconsistent across studies. Future research should explore the long-term effects of these external supports, analyze the effects of different characteristics and combinations of supports, and employ standardized outcome measures and testing protocols for assessing postural stability.

Advances on mechanical designs for assistive ankle-foot orthoses

Assistive ankle-foot orthoses (AAFOs) are powerful solutions to assist or rehabilitate gait on humans. Existing AAFO technologies include passive, quasi-passive, and active principles to provide assistance to the users, and their mechanical configuration and control depend on the eventual support they aim for within the gait pattern. In this research we analyze the state-of-the-art of AAFO and classify the different approaches into clusters, describing their basis and working principles. Additionally, we reviewed the purpose and experimental validation of the devices, providing the reader with a better view of the technology readiness level. Finally, the reviewed designs, limitations, and future steps in the field are summarized and discussed.

Design and Additive Manufacturing of a Passive Ankle-Foot Orthosis Incorporating Material Characterization for Fiber-Reinforced PETG-CF15

The individualization of patient-specific ankle joint orthoses is becoming increasingly important and can be ideally realized by means of additive manufacturing. However, currently, there are no functional additively manufactured fiber-reinforced products that are used in the field of orthopedic treatment. In this paper, an approach as to how additively manufactured orthopedic products can be designed and produced quickly and flexibly in the future is presented. This is demonstrated using the example of a solid ankle-foot orthosis. For this purpose, test results on PETG-CF15, which were determined in a previous work, were integrated into a material map for an FEA simulation. Therewith, the question can be answered as to whether production parameters that were determined at the test specimen level can also be adapted to real, usable components. Furthermore, gait recordings were used as loading conditions to obtain exact results for the final product. In order to perfectly adapt the design of the splint to the user, a 3D scan of a foot was performed to obtain a perfect design space for topology optimization. This resulted in a patient-specific and stiffness-optimized product. Subsequently, it was demonstrated that the orthosis could be manufactured using fused layer modelling. Finally, a comparison between the conventional design and the consideration of AM-specific properties was made. On this basis, it can be stated that the wearing comfort of the patient-specific design is very good, but the tightening of the splint still needs to be improved.

Passive Articulated and Non-Articulated Ankle-Foot Orthoses for Gait Rehabilitation: A Narrative Review

The aim of this work was to study the different types of passive articulated and non-articulated ankle-foot orthoses for gait rehabilitation in terms of working principles, control mechanisms, features, and limitations, along with the recent clinical trials on AFOs. An additional aim was to categorize them to help engineers and orthotists to develop novel designs based on this research. Based on selected keywords and their composition, a search was performed on the ISI Web of Knowledge, Google Scholar, Scopus, and PubMed databases from 1990 to 2022. Forty-two studies met the eligibility criteria, which highlighted the commonly used types and recent development of passive articulated and non-articulated ankle-foot orthoses for foot drop. Orthotists and engineers may benefit from the information obtained from this review article by enhancing their understanding of the challenges in developing an AFO that meets all the requirements in terms of ease of use, freedom of movement, and high performance at a relatively low cost.

Neck Collar Assessment for People Living With Motor Neuron Disease: Are Current Outcome Measures Suitable?

A majority of people living with motor neuron disease (MND) experience weakness of the neck and as a result, experience head drop. This exacerbates problems with everyday activities (eating, talking, breathing, etc). Neck collars are often used to support head drop; however, these are typically designed for prehospitalization settings to manage and brace the cervical region of the spine. As a result, it has been recorded that people living with MND often reject these collars for a variety of reasons but most notably because they are too restricting. The current standardized outcome measures (most notably restricting cervical range of motion) used for neck collars are summarized herein along with whether they are suitable for a bespoke neck collar specifically designed for people living with MND.

Numerical and Experimental Mechanical Analysis of Additively Manufactured Ankle-Foot Orthoses

Growing age and different conditions often require the replacement of orthoses, and FDM-based 3D printing can produce them quickly with less investment. In today's market for orthotics, these characteristics are highly desired. Therefore, this study is fully focused on the optimization and strength analysis of FDM 3D-printed ankle-foot orthoses (AFO) fabricated using PLA and PLA reinforced with carbon fiber (PLA-C). An increase in ankle plantar-flexor force can be achieved by reinforcing thermoplastic AFOs with CFs. Specially designed mechanical strength tests were conducted at the UTM to generate force-displacement curves for stored elastic energy and fracture studies. The mechanical behavior of both AFOs was predicted with the help of an FEA. The model predictions were validated by comparing them with mechanical strength testing conducted under the same loading and boundary conditions as the FEA. In both the prediction and experimental analysis, the PLA-C-based AFOs were stiffer and could withstand greater loads than the PLA-based AFOs. An area of high stress in the simulation and a fracture point in experimentation were both found at the same location. Furthermore, these highly accurate models will allow the fabrication of AFOs to be improved without investing time and resources on trials.