An individual approach for optimizing ankle-foot orthoses to improve mobility in children with spastic cerebral palsy walking with excessive knee flexion

Exploring the rationale for prescribing ankle-foot orthoses and supramalleolar orthoses in children with cerebral palsy: A narrative synthesis of rationale statements

BACKGROUND

To help improve outcomes for children with cerebral palsy (CP), ankle-foot orthoses (AFOs) and supramalleolar orthoses (SMOs) are prescribed. However, it is not clear why one intervention is prescribed over the other.

OBJECTIVES

To explore the rationale for prescribing AFOs and SMOs in children with CP and its link to the choice of outcome measure used.

STUDY DESIGN

Narrative review.

METHODS

Six databases were searched (eg, Medline) and data extracted from articles that met the inclusion criteria. Data describing the participant demographics, type of orthosis, and outcome measures used were summarized to provide context for the different rationale for orthotic prescription that were thematically analyzed.

DISCUSSION

Forty-seven articles were included. Participants were aged 9 ± 2 years, 59% were male, 79% had diplegia, and 38% were classified as Gross Motor Function Classification System level I. All studies included a rationale for prescribing AFOs that, in most cases, reflected the outcome measures used. These rationale statements were synthesized into 5 specific themes (e.g., reduced energy expenditure and metabolic costs). By comparison, 5 of these studies described the rationale for providing SMOs, and of those that did, most of the rationale statements were nonspecific.

CONCLUSIONS

A large and contemporary body of literature describes the rationale for prescribing AFOs for children with CP. There are opportunities for future research that clearly articulates the rationale for prescribing SMOs for children living with CP and to focus the rational for orthotic intervention on the real-world challenges that are most important to children living with CP, such as the ability to participate among peers.

Effect of stiffness-optimized ankle foot orthoses on joint work in adults with neuromuscular diseases is related to severity of push-off deficits

BACKGROUND

People with plantar flexor weakness generate less ankle push-off work during walking, resulting in inefficient proximal joint compensations. To increase push-off work, spring-like ankle foot orthoses (AFOs) can be provided. However, whether and in which patients AFOs increase push-off work and reduce compensatory hip and knee work is unknown.

METHODS

In 18 people with bilateral plantar flexor weakness, we performed a 3D gait analysis at comfortable walking speed with shoes-only and with AFOs of which the stiffness was optimized. To account for walking speed differences between conditions, we compared relative joint work of the hip, knee and ankle joint. The relationships between relative work generated with shoes-only and changes in joint work with AFO were tested with Pearson correlations.

RESULTS

No differences in relative ankle, knee and hip work over the gait cycle were found between shoes-only and AFO (p>0.499). Percentage of total ankle work generated during pre-swing increased with the AFO (AFO: 85.3±9.1% vs Shoes: 72.4±27.1%, p=0.026). At the hip, the AFO reduced relative work in pre-swing (AFO: 31.9±7.4% vs Shoes: 34.1±10.4%, p=0.038) and increased in loading response (AFO: 18.0±11.0% vs Shoes: 11.9±9.8%, p=0.022). Ankle work with shoes-only was inversely correlated with an increase in ankle work with AFO (r=-0.839, p<0.001) and this increase correlated with reduction in hip work with AFO (r=-0.650, p=0.004).

DISCUSSION

Although stiffness-optimized AFOs did not alter the work distribution across the ankle, knee and hip joint compared to shoes-only walking, relative more ankle work was generated during push-off, causing a shift in hip work from pre-swing to loading response. Furthermore, larger ankle push-off deficits when walking with shoes-only were related with an increase in ankle work with AFO and reduction in compensatory hip work, indicating that more severely affected individuals benefit more from the energy storing-and-releasing capacity of AFOs.

Effects of ankle-foot orthoses on step activities in the community: a systematic review

PURPOSE

To determine the effects of ankle-foot orthoses (AFO) on step-based physical activities in individuals with neurological, orthopaedic, or cardiovascular disorders.

METHODS

Electronic searches of databases such as Scopus, PubMed, Web of Science, Embase, ProQuest, Cochrane Library, and EBSCO were conducted. Two evaluators independently searched with keywords focusing on step-based physical activities, and either articulated or non-articulated AFO. Study quality was assessed using a modified Downs and Black quality scale.

RESULTS

Eleven studies that met the inclusion criteria were selected, including four being classified as good, four as fair, and three as poor in quality. The majority of these trials found no significant effects of AFO on step activities. Only a few studies reported improvements in step counts and active times in step activity with a limited to moderate level of evidence. Subjective evaluations such as user satisfaction, and physical functionality during step activity, on the other hand, showed substantial changes with the use of AFO interventions, although there was no evidence of improvement in the quality of life.

CONCLUSIONS

Although the AFO did not seem to have a substantial effect on step activity, it appeared to play a vital role in improving the patient satisfaction level of step activity.IMPLICATIONS FOR REHABILITATIONAnkle-foot orthoses (AFO) may not significantly affect the step activity of individuals with impaired ankle-foot complex.AFO may enhance patient-reported satisfaction, physical functioning, participation, and fatigue level during step activity.The patient's perception that the AFO is beneficial is in contrast to objective data showing no significant increase in real-world activity.

Ankle dorsiflexion assistance of patients with foot drop using a powered ankle-foot orthosis to improve the gait asymmetry

BACKGROUND

Foot drop is a neuromuscular disorder that causes abnormal gait patterns. This study developed a pneumatically powered ankle-foot orthosis (AFO) to improve the gait patterns of patients with foot drop. We hypothesized that providing unilateral ankle dorsiflexion assistance during the swing phase would improve the kinematics and spatiotemporal gait parameters of such patients. Accordingly, this study aims to examine the efficacy of the proposed assistance system using a strategy for joint kinematics and spatiotemporal gait parameters (stride length, swing velocity, and stance phase ratio). The analysis results are expected to provide knowledge for better design and control of AFOs in patients with foot drop.

METHOD

Ten foot drop patients with hemiparesis (54.8 y ± 14.1 y) were fitted with a custom AFO with an adjustable calf brace and portable air compressor for ankle dorsiflexion assistance in the gait cycle during the swing phase. All subjects walked under two different conditions without extensive practice: (1) barefoot and (2) wearing a powered AFO. Under each condition, the patients walked back and forth on a 9-m track with ten laps of level ground under the supervision of licensed physical therapists. The lower-limb joint and trunk kinematics were acquired using 12 motion-capture cameras.

RESULTS

We found that kinematic asymmetry decreased in the three lower-limb joints after ankle dorsiflexion assistance during the swing phase. The average ankle-joint angle increased after using the AFO during the entire gait cycle. Similarly, the knee-joint angle showed a slight increase while using the AFO, leading to a significantly decreased standard deviation within patients. Conversely, the hip-joint angle showed no significant improvements with assistance. While several patients exhibited noticeably lower levels of asymmetry, no significant changes were observed in the average asymmetry of the swing velocity difference between the affected and unaffected sides while using the AFO.

CONCLUSION

We experimentally validated that ankle dorsiflexion assistance during the swing phase temporarily improves gait asymmetry in foot-drop patients. The experimental results also prove the efficacy of the developed AFO for gait assistance in foot-drop patients.

Effects of ankle-foot orthoses on different gait patterns in children with spastic cerebral palsy: A statistical parametric mapping study

BACKGROUND

Ankle-foot orthoses (AFOs) are a common treatment to correct gait deviations in children with spastic cerebral palsy (SCP). Studies on the outcome of AFOs on gait often do not account for different gait patterns.

OBJECTIVES

The aim of this study was to investigate the effects of AFOs on specific gait patterns in children with cerebral palsy.

STUDY DESIGN

Retrospective, unblinded, controlled, cross-over study.

METHODS

Twenty-seven children with SCP were assessed in the conditions walking barefoot or with shoes and AFO. AFOs were prescribed based on usual clinical practice. Gait patterns for each leg were classified as excess ankle plantarflexion in stance (equinus), excess knee extension in stance (hyperextension), or excess knee flexion in stance (crouch). Differences in spatial-temporal variables and sagittal kinematics and kinetics of the hip, knee, and ankle between the 2 conditions were determined using paired t-tests and statistical parametric mapping, respectively. The effect of AFO-footwear neutral angle on knee flexion was tested using statistical parametric mapping regression.

RESULTS

AFO use improved spatial-temporal variables and reduced ankle power generation in preswing. For "equinus" and "hyperextension" gait patterns, AFOs decreased ankle plantarflexion in preswing and initial swing and decreased ankle power in preswing. Ankle dorsiflexion moment increased in all gait pattern groups. Knee and hip variables did not change in any of the 3 groups. AFO-footwear neutral angle had no effect on changes in sagittal knee angle.

CONCLUSION

Although improvements in spatial-temporal variables were seen, gait deviations could only partially be corrected. Therefore, AFO prescriptions and design should individually address specific gait deviations and their effectiveness in children with SCP should be controlled.

Design principles, manufacturing and evaluation techniques of custom dynamic ankle-foot orthoses: a review study

Ankle-Foot Orthoses (AFO) can be prescribed to allow drop-foot patients to restore a quasi-normal gait pattern. Standard off-the-shelf AFOs are cost-effective solutions to treat most patients with foot and ankle weakness, but these devices have several limitations, especially in terms of comfort. Therefore, custom AFOs are increasingly adopted to address drop-foot when standard solutions are not adequate. While the solid ones are the most common type of AFO, providing full stability and strong resistance to ankle plantarflexion, passive dynamic AFOs (PD-AFOs) represent the ideal solution for patients with less severe ankle weakness. PD-AFOs have a flexible calf shell, which can bend during the stance phase of walking and absorb energy that can be released to support the limb in the push-off phase. The aim of this review is to assess the state-of-the-art and identify the current limitations of PD-AFOs. An extensive literature review was performed in Google Scholar to identify all studies on custom PD-AFOs. Only those papers reporting on custom PD-AFOs were included in the review. Non peer-reviewed papers, abstract shorter than three pages, lecture notes and thesis dissertations were excluded from the analysis. Particular attention was given to the customization principles and the mechanical and functional tests. For each topic, the main results from all relevant papers are reported and summarized herein. There were 75 papers that corresponded to the search criteria. These were grouped according to the following macro-topics: 16 focusing on scanning technologies and geometry acquisition; 14 on customization criteria; 19 on production techniques; 16 on mechanical testing, and 33 on functional testing. According to the present review, design and production of custom PD-AFOs are becoming increasingly feasible due to advancements in 3D scanning techniques and additive manufacturing. In general, custom PD-AFOs were shown to provide better comfort and improved spatio-temporal parameters with respect to standard solutions. However, no customization principle to adapt PD-AFO stiffness to the patient's degree of ankle impairment or mechanical/functional demand has thus far been proposed.

Energy cost optimized dorsal leaf ankle-foot-orthoses reduce impact forces on the contralateral leg in people with unilateral plantar flexor weakness

BACKGROUND

In individuals with unilateral plantar flexor weakness, the second peak of the vertical ground reaction force (GRF) is decreased. This leads to a higher ground reaction force, e.g. impact, of the contralateral leg, potentially explaining quadriceps muscle and/or knee joint pain. Energy cost optimized dorsal leaf ankle-foot-orthoses (AFOs) may increase the push-off ground reaction force, which in turn could lead to lower impact forces on the contralateral leg.

RESEARCH QUESTIONS

1) Are impact forces increased in the contralateral leg of people with unilateral plantar flexor weakness compared to healthy subjects? 2) Do energy cost optimized AFOs reduce impact forces and improve leg impact symmetry compared to walking without AFO in people with unilateral plantar flexor weakness?

METHODS

Nine subjects with unilateral plantar flexor weakness were provided a dorsal leaf AFO with a stiffness primarily optimized for energy cost. Using 3D gait analyses peak vertical GRF during loading response with and without AFO, and the symmetry between the legs in peak GRF were calculated. Peak GRF and symmetry were compared with reference data of 23 healthy subjects.

RESULTS

The contralateral leg showed a significant higher peak vertical GRF (12.0 ± 0.9 vs 11.2 ± 0.6 N/kg, p = 0.005) compared to healthy reference data. When walking with AFO, the peak vertical GRF of the contralateral leg significantly reduced (from 12.0 ± 0.9 to 11.4 ± 0.7 N/kg, p = 0.017) and symmetry improved compared to no AFO (from 0.93 ± 0.06 to 1.01 ± 0.05, p < 0.001).

CONCLUSION

In subjects with unilateral plantar flexor weakness, impact force on the contralateral leg was increased when compared to healthy subjects and dorsal leaf AFOs optimized for energy cost substantially reduced this force and improved impact symmetry when compared to walking without AFO. This indicates that dorsal leaf AFOs may reduce pain resulting from increased impact forces during gait in the contralateral leg in people with unilateral plantar flexor weakness.

Effects of Ankle Foot Orthoses on the Gait Patterns in Children with Spastic Bilateral Cerebral Palsy: A Scoping Review

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.

Understanding the effects of quantitatively prescribing passive-dynamic ankle-foot orthosis bending stiffness for individuals after stroke

BACKGROUND

Passive-dynamic ankle-foot orthosis (PD-AFO) bending stiffness, which assists plantar flexor function, can be prescribed to improve poststroke gait. However, outcomes with PD-AFOs are variable likely because of improper personalization. We implemented a prescription model that objectively personalizes PD-AFO bending stiffness based on each individual's level of plantar flexor weakness (quantitatively prescribed PD-AFO).

OBJECTIVES

To evaluate whether a quantitatively prescribed PD-AFO improves peak paretic plantar flexion moment compared with the original AFO for individuals after stroke and to examine the immediate effects of wearing a quantitatively prescribed PD-AFO.

STUDY DESIGN

This is a repeated-measures study.

METHODS

PD-AFO bending stiffness was personalized for 10 individuals after stroke through the previously developed prescription model. Participants underwent an instrumented gait analysis while wearing their original AFO and the quantitatively prescribed PD-AFO.

RESULTS

Participants' peak paretic plantar flexion moment significantly increased while wearing the quantitatively prescribed PD-AFO compared with the original AFO. In addition, participants showed different levels of improvements in a series of other key biomechanical and walking performance parameters with PD-AFO use. Some participants showed improvements in all parameters, whereas others showed moderate to no improvements.

CONCLUSIONS

Quantitatively prescribed PD-AFO bending stiffness resulted in inconsistent improvements in biomechanical and walking performance parameters, which warrants further investigation. Future work should investigate whether more consistent benefits are seen with faster walking speeds and longer-term PD-AFO use. In addition, future work should conduct larger-scale studies that aim to understand and optimize orthosis-patient matching for all AFO designs/characteristics.

The effects of footplate stiffness on push-off power when walking with posterior leaf spring ankle-foot orthoses

BACKGROUND

Many studies on ankle-foot orthoses investigated the optimal stiffness around the ankle, while the effect of footplate stiffness has been largely ignored. This study investigated the effects of ankle-foot orthosis footplate stiffness on ankle-foot push-off power during walking in able-bodied persons.

METHODS

Twelve healthy participants walked at a fixed speed (1.25 m·s^-1) on an instrumented treadmill in four conditions: shod and with a posterior leaf-spring orthosis with a flexible, stiff or rigid footplate. For each trial, ankle kinematics and kinetics were averaged over one-minute walking. Separate contributions of the ankle joint complex and distal hindfoot to total ankle-foot power and work were calculated using a deformable foot model.

FINDINGS

Peak ankle joint power was significantly higher with the rigid footplate compared to the flexible and stiff footplate and not different from shod walking. The stiff footplate increased peak hindfoot power compared to the flexible and rigid footplate and shod walking. Total ankle-foot power showed a significant increase with increasing footplate stiffness, where walking with the rigid footplate was comparable to shod walking. Similar effects were found for positive mechanical work.

INTERPRETATION

A rigid footplate increases the lever of the foot, resulting in an increased ankle moment and energy storage and release of the orthosis' posterior leaf-spring as reflected in higher ankle joint power. This effect dominates the power generation of the foot, which was highest with the intermediate footplate stiffness. Future studies should focus on how tuning footplate stiffness could contribute to optimizing ankle-foot orthosis efficacy in clinical populations.

Individual stiffness optimization of dorsal leaf spring ankle-foot orthoses in people with calf muscle weakness is superior to standard bodyweight-based recommendations

BACKGROUND

In people with calf muscle weakness, the stiffness of dorsal leaf spring ankle-foot orthoses (DLS-AFO) needs to be individualized to maximize its effect on walking. Orthotic suppliers may recommend a certain stiffness based on body weight and activity level. However, it is unknown whether these recommendations are sufficient to yield the optimal stiffness for the individual. Therefore, we assessed whether the stiffness following the supplier's recommendation of the Carbon Ankle7 (CA7) dorsal leaf matched the experimentally optimized AFO stiffness.

METHODS

Thirty-four persons with calf muscle weakness were included and provided a new DLS-AFO of which the stiffness could be varied by changing the CA7® (Ottobock, Duderstadt, Germany) dorsal leaf. For five different stiffness levels, including the supplier recommended stiffness, gait biomechanics, walking energy cost and speed were assessed. Based on these measures, the individual experimentally optimal AFO stiffness was selected.

RESULTS

In only 8 of 34 (23%) participants, the supplier recommended stiffness matched the experimentally optimized AFO stiffness, the latter being on average 1.2 ± 1.3 Nm/degree more flexible. The DLS-AFO with an experimentally optimized stiffness resulted in a significantly lower walking energy cost (- 0.21 ± 0.26 J/kg/m, p < 0.001) and a higher speed (+ 0.02 m/s, p = 0.003). Additionally, a larger ankle range of motion (+ 1.3 ± 0.3 degrees, p < 0.001) and higher ankle power (+ 0.16 ± 0.04 W/kg, p < 0.001) were found with the experimentally optimized stiffness compared to the supplier recommended stiffness.

CONCLUSIONS

In people with calf muscle weakness, current supplier's recommendations for the CA7 stiffness level result in the provision of DLS-AFOs that are too stiff and only achieve 80% of the reduction in energy cost achieved with an individual optimized stiffness. It is recommended to experimentally optimize the CA7 stiffness in people with calf muscle weakness in order to maximize treatment outcomes. Trial registration Nederlands Trial Register 5170. Registration date: May 7th 2015. http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=5170 .

The Codivilla Spring: from then to now and beyond

The ankle-foot-orthosis (AFO), originally called Codivilla Spring, is an orthotic device prescribed to the patients with foot drop due to neurological diseases in order to control the range of motion of the ankle joint, to compensate for the muscle weakness/spasticity thus optimizing the gait function. In this paper, a historical revision of the most known and used AFO worldwide from the origin of its name and the first applications at the Rizzoli Orthopedic Institute to the most advanced solutions in use today is covered. Through the critical analysis of historical documents available, the paper reports on the controversy about the true inventor of the Codivilla Spring during the first decades of the twentieth century. Main current adult and child AFOs, in terms of their design and indications are presented. Finally, possible approaches for the selection of the correct orthosis and the individual prescription are discussed in order to manage specific mechanical neuromuscular deficiencies of the subject's ankle-foot complex optimizing walking efficiency.

Evidence Based Position Paper on Physical and Rehabilitation Medicine professional practice for persons with cerebral palsy

INTRODUCTION

Cerebral palsy (CP) is a group of the most common developmental disorders affecting movement and posture of the body, causing activity limitations and participation restrictions. The motor disorders of persons with CP are often accompanied by disturbances of sensation, cognition, communication and perception. The symptoms of CP are very diverse and persons with CP are usually presented with a mixed type of symptoms. The non-progressive disturbances can be attributed to disorders that were developed during pregnancy, birth and/or infant stage.

AIM

The aim of this study was to improve Physical and Rehabilitation Medicine physician´s professional practice for persons with cerebral palsy in order to improve their functionality, social and community integration, and to reduce activity limitations and/or participation restrictions.

MATERIAL AND METHODS

A systematic review of the literature including an eighteen-year period and consensus procedure by means of a Delphi process was performed and involved the delegates of all European countries represented in the Union of European Medical Specialists Physical and Rehabilitation Medicine (UEMS PRM) Section.

RESULTS

As the result of a Consensus Delphi procedure process 74 recommendations are presented together with the systematic literature review.

CONCLUSIONS

The PRM physician´s role for persons with cerebral palsy is to lead and coordinate the multiprofessional team, working in an interdisciplinary way. They should propose and manage the complex but individual PRM programme developed in conjunction with other health professionals, medical specialists and importantly in agreement with the patient, their family and care giver. This should be, according to the specific medical diagnosis to improve patients´ health, functioning, social and education status, considering all impairments, comorbidities and complications, activity limitations and participation restrictions.

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

BACKGROUND

Crouch or flexed-knee gait is one of the most common pathological gait patterns in cerebral palsy (CP). Differences exist in definitions used; the degree of knee flexion, inclusion of hip or ankle position, and timing in the gait cycle. This ambiguity may be responsible for variations in prevalence rates and difficulty comparing data across studies.

RESEARCH QUESTION

What are the kinematic parameters used to define crouch or flexed-knee gait in CP gait? A secondary aim was to examine the quality of data reporting, focusing on the sample characteristics, inclusion/exclusion criteria and the choice of limb included for analysis.

METHODS

Articles included in this review reported on a specified cohort of adults or children with crouch or flexed-knee gait assessed with 3-dimensional gait analysis. A customised data extraction and quality assessment table was designed specific to the research question.

RESULTS

The majority (75 %) of included studies used the term crouch gait. Where the pattern was defined, 80 % of crouch papers and 94 % of flexed-knee gait papers based this solely on knee position. Kinematic parameters were clearly defined when they provided objective values of knee flexion, supported this with rationale and provided a reference point in the gait cycle. Only 22 % of crouch papers and 19 % of flexed-knee gait papers provided this information. The majority of studies (67 % crouch; 90 % flexed-knee) specified which limb(s) were included for analysis with the majority including both limbs. Objective values of knee flexion ranged from 8 o to 30 o.

SIGNIFICANCE

This review highlights that crouch and flexed knee are synonymous and ambiguity exists in the kinematic definition making it difficult to make compare data amongst study cohorts. Future research should provide detailed definitions including the threshold value of knee flexion, how it was derived, the timing in the gait cycle and the limb(s) included in analysis.

What's New in the Orthopaedic Treatment of Ambulatory Children With Cerebral Palsy Using Gait Analysis

BACKGROUND

Limb deformities in ambulatory children with cerebral palsy (CP) are common. The natural history of lower extremity deformities is variable and the impact on gait is managed with many treatment modalities. Effective interventions must consider the underlying pathophysiology, patient-specific goals, and incorporate objective outcome assessment. Evaluation and treatment include observation, tone management multilevel orthopaedic surgery to address muscle contractures and bony deformities, and the use of gait analysis for preoperative and postoperative assessment.

METHODS

A PubMed search of the orthopaedic literature for studies published between January 2016 and February 2019 was performed. Eligible abstracts included the use of 3-dimensional instrumented gait analysis in the evaluation and treatment of the lower extremities in ambulatory children with CP. Seven hundred twenty abstracts were reviewed, with 84 papers identified as eligible, of which 45 full manuscripts were included for detailed review.

RESULTS

The review summarized recent advances regarding the treatment of torsional alignment, knee deformities and clinical gait evaluation with visual assessment tools compared with instrumented gait analysis.

CONCLUSIONS

Gait analysis of ambulatory children with CP remains essential to evaluation and surgical decision-making. Promising results have been reported with the goal of maintaining or reaching a higher level of function and increased endurance.

LEVEL OF EVIDENCE

Level IV-literature review.

An Unsupervised Data-Driven Model to Classify Gait Patterns in Children with Cerebral Palsy

Ankle and foot orthoses are commonly prescribed to children with cerebral palsy (CP). It is unclear whether 3D gait analysis (3DGA) provides sufficient and reliable information for clinicians to be consistent when prescribing orthoses. Data-driven modeling can probe such questions by revealing non-intuitive relationships between variables such as 3DGA parameters and gait outcomes of orthoses use. The purpose of this study was to (1) develop a data-driven model to classify children with CP according to their gait biomechanics and (2) identify relationships between orthotics types and gait patterns. 3DGA data were acquired from walking trials of 25 typically developed children and 98 children with CP with additional prescribed orthoses. An unsupervised self-organizing map followed by k-means clustering was developed to group different gait patterns based on children's 3DGA. Model inputs were gait variable scores (GVSs) extracted from the gait profile score, measuring root mean square differences from TD children's gait cycle. The model identified five pathological gait patterns with statistical differences in GVSs. Only 43% of children improved their gait pattern when wearing an orthosis. Orthotics prescriptions were variable even in children with similar gait patterns. This study suggests that quantitative data-driven approaches may provide more clarity and specificity to support orthotics prescription.

Ankle foot orthoses in cerebral palsy: Effects of ankle stiffness on trunk kinematics, gait stability and energy cost of walking

In children with cerebral palsy (CP), rigid ventral shell ankle-foot orthoses (vAFOs) are often prescribed to reduce excessive knee flexion in stance and lower the energy cost of walking (ECW). However, how vAFOs affect ECW is a complex issue, as vAFOs may have an impact on lower limb biomechanics, upper body movements, and balance. Besides, the vAFO's biomechanical effect have been shown to be dependent on its stiffness around the ankle joint. We examined whether vAFO stiffness influences trunk movements and gait stability in CP, and whether there is a relationship between these factors and ECW. Fifteen children with spastic CP were prescribed vAFOs. Stiffness was varied into a rigid, stiff and flexible configuration. At baseline (shoes-only) and for each vAFO stiffness configuration, 3D-gait analyses and ECW-tests were performed. From the gait analyses, we derived trunk tilt, lateroflexion, and rotation range of motion (RoM) and the mediolateral and anteroposterior Margins of Stability (MoS) and their variability as measures of gait stability. With the ECW-test we determined the netEC. We found that wearing vAFOs significantly increased trunk lateroflexion (Wald χ2 = 33.7, p < 0.001), rotation RoM (Wald χ2 = 20.5, p < 0.001) and mediolateral gait instability (Wald χ2 = 10.4, p = 0.016). The extent of these effects partly depended on the stiffness of the vAFO. Significant relations between trunk movements, gait stability and ECW were found r = 0.57-0.81, p < 0.05), which indicates that trunk movements and gait stability should be taken into account when prescribing vAFOs to improve gait in children with CP walking with excessive knee flexion.

A wearable gait analysis protocol to support the choice of the appropriate ankle-foot orthosis: A comparative assessment in children with Cerebral Palsy

BACKGROUND

Cerebral Palsy is, nowadays, the most common cause of pediatric disabilities, particularly debilitating for daily living activities. While the adoption of ankle-foot orthoses is very well established as gait treatment, the choice of the most appropriate orthotic configuration is not strongly supported by scientific evidence. The aim of this study was to develop an instrumented assessment protocol based on wearable gait analysis to support clinicians in ankle-foot orthoses configuration selection.

METHODS

Ten children with spastic diplegic Cerebral Palsy were assessed (7 males, aged 4 to 11 years; all functionally classified as Gross Motor Function Classification System I or II, with clinical indication of conservative treatment through use of ankle-foot orthoses). They performed a 10Meter Walk Test in three conditions: barefoot and wearing alternatively a polypropylene hinged and solid ankle-foot orthosis accommodated in the same off-the-shelf shoe model, after 20 days of daily use of each configuration. An instrumented assessment protocol based on body-mounted magneto-inertial sensors was devised to derive spatio-temporal, gait stability and symmetry biomechanical parameters within an observational pre and post cross over design.

FINDINGS

The analysis at the individual level quantitatively revealed how different patients benefited differently from the two orthoses. No general indications were obtained in favour of or against a specific configuration for the sample as a whole.

INTERPRETATION

The proposed instrumented protocol represents a quantitative and useful tool to support the clinical selection of an appropriate orthotic treatment and, potentially, in evaluating its effectiveness.

Modifying ankle foot orthosis stiffness in patients with calf muscle weakness: gait responses on group and individual level

Background

To improve gait, persons with calf muscle weakness can be provided with a dorsal leaf spring ankle foot orthosis (DLS-AFO). These AFOs can store energy during stance and return this energy during push-off, which, in turn, reduces walking energy cost. Simulations indicate that the effect of the DLS-AFO on walking energy cost and gait biomechanics depends on its stiffness and on patient characteristics. We therefore studied the effect of varying DLS-AFO stiffness on reducing walking energy cost, and improving gait biomechanics and AFO generated power in persons with non-spastic calf muscle weakness, and whether the optimal AFO stiffness for maximally reducing walking energy cost varies between persons.

Methods

Thirty-seven individuals with neuromuscular disorders and non-spastic calf muscle weakness were included. Participants were provided with a DLS-AFO of which the stiffness could be varied. For 5 stiffness configurations (ranging from 2.8 to 6.6 Nm/degree), walking energy cost (J/kg/m) was assessed using a 6-min comfortable walk test. Selected gait parameters, e.g. maximal dorsiflexion angle, ankle power, knee angle, knee moment and AFO generated power, were derived from 3D gait analysis.

Results

On group level, no significant effect of DLS-AFO stiffness on reducing walking energy cost was found (p = 0.059, largest difference: 0.14 J/kg/m). The AFO stiffness that reduced energy cost the most varied between persons. The difference in energy cost between the least and most efficient AFO stiffness was on average 10.7%. Regarding gait biomechanics, increasing AFO stiffness significantly decreased maximal ankle dorsiflexion angle (− 1.1 ± 0.1 degrees per 1 Nm/degree, p < 0.001) and peak ankle power (− 0.09 ± 0.01 W/kg, p < 0.001). The reduction in minimal knee angle (− 0.3 ± 0.1 degrees, p = 0.034), and increment in external knee extension moment in stance (− 0.01 ± 0.01 Nm/kg, p = 0.016) were small, although all stiffness’ substantially affected knee angle and knee moment compared to shoes only. No effect of stiffness on AFO generated power was found (p = 0.900).

Conclusions

The optimal efficient DLS-AFO stiffness varied largely between persons with non-spastic calf muscle weakness. Results indicate this is caused by an individual trade-off between ankle angle and ankle power affected differently by AFO stiffness. We therefore recommend that the AFO stiffness should be individually optimized to best improve gait.

Trial registration number

Nederlands Trial Register 5170. Registration date: May 7th 2015. http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=5170

A study on the efficacy of AFO stiffness prescriptions

PURPOSE

Ankle foot orthosis (AFO) stiffness is a key characteristic that determines how much support or restraint an AFO can provide. Thus, the goal of the current study is twofold: (1) to quantify AFO prescriptions for a group of patients; (2) to evaluate what impact these AFO have on the push-off phase.

METHOD

Six patients were included in the study. Three patients were prescribed an AFO for ankle support and three patients were prescribed an AFO for ankle and knee support. Two types of AFO - a traditional polypropylene AFO (AFOPP) and a novel carbon-selective laser sintered polyamide AFO (AFOPA), were produced for each patient. AFO ankle stiffness was measured in a dedicated test rig. Gait analysis was performed under shod and orthotic conditions.

RESULTS

Patient mass normalized AFOPP stiffness for ankle support ranged from 0.042 to 0.069 N·m·deg^-1·kg^-1, while for ankle and knee support it ranged from 0.081 to 0.127 N·m·deg^-1·kg^-1. On the group level, the ankle range of motion and mean ankle velocity in the push-off phase significantly decreased in both orthotic conditions, while peak ankle push-off power decreased non-significantly. Accordingly, on the group level, no significant improvements in walking speed were observed. However, after patient differentiation into good and bad responders it was found that in good responders peak ankle push-off power tended to be preserved and walking speed tended to increase.

CONCLUSIONS

Quantification of AFO stiffness may help to understand why certain orthotic interventions are successful (unsuccessful) and ultimately lead to better AFO prescriptions. Implications for rehabilitation AFO ankle stiffness is key characteristic that determines how much support or restraint an AFO can provide. In a typical clinical setting, AFO ankle stiffness is not quantified. AFO has to meet individual patient's biomechanical needs. More objective AFO prescription and more controlled AFO production methods are needed to increase AFO success rate.

Effect of ankle-foot orthoses on gait, balance and gross motor function in children with cerebral palsy: a systematic review and meta-analysis

Objective:

To determine the effects of ankle-foot orthoses (AFOs) on gait, balance, gross motor function and activities of daily living in children with cerebral palsy.

Data sources:

Five databases were searched (Pubmed, Psycinfo, Web of Science, Academic Search Premier and Cochrane Library) before January 2018.

Review methods:

Studies of the effect of AFOs on gait, balance, gross motor function and activities of daily living in children with cerebral palsy were included. Articles with a modified PEDRO score ≥ 5/9 were selected. Data regarding population, AFO, interventions and outcomes were extracted. When possible, standardized mean differences (SMDs) were calculated from the outcomes.

Results:

Thirty-two articles, corresponding to 56 studies (884 children) were included. Fifty-one studies included children with spastic cerebral palsy. AFOs increased stride length (SMD = 0.88, P < 0.001) and gait speed (SMD = 0.28, P < 0.001), and decreased cadence (SMD = –0.72, P < 0.001). Gross motor function scores improved (Gross Motor Function Measure (GMFM) D (SMD = 0.30, P = 0.004), E (SMD = 0.28, P = 0.02), Pediatric Evaluation of Disability Inventory (PEDI) (SMD = 0.57, P < 0.001)). Data relating to balance and activities of daily living were insufficient to conclude. Posterior AFOs (solid, hinged, supra-malleolar, dynamic) increased ankle dorsiflexion at initial contact (SMD = 1.65, P < 0.001) and during swing (SMD = 1.34, P < 0.001), and decreased ankle power generation in stance (SMD = –0.72, P < 0.001) in children with equinus gait.

Conclusion:

In children with spastic cerebral palsy, there is strong evidence that AFOs induce small improvements in gait speed and moderate evidence that AFOs have a small to moderate effect on gross motor function. In children with equinus gait, there is strong evidence that posterior AFOs induce large changes in distal kinematics.

Outcome of medial hamstring lengthening in children with spastic paresis: A biomechanical and morphological observational study

To improve gait in children with spastic paresis due to cerebral palsy or hereditary spastic paresis, the semitendinosus muscle is frequently lengthened amongst other medial hamstring muscles by orthopaedic surgery. Side effects on gait due to weakening of the hamstring muscles and overcorrections have been reported. How these side effects relate to semitendinosus morphology is unknown. This study assessed the effects of bilateral medial hamstring lengthening as part of single-event multilevel surgery (SEMLS) on (1) knee joint mechanics (2) semitendinosus muscle morphology and (3) gait kinematics. All variables were assessed for the right side only. Six children with spastic paresis selected for surgery to counteract limited knee range of motion were measured before and about a year after surgery. After surgery, in most subjects popliteal angle decreased and knee moment-angle curves were shifted towards a more extended knee joint, semitendinosus muscle belly length was approximately 30% decreased, while at all assessed knee angles tendon length was increased by about 80%. In the majority of children muscle volume of the semitendinosus muscle decreased substantially suggesting a reduction of physiological cross-sectional area. Gait kinematics showed more knee extension during stance (mean change ± standard deviation: 34±13°), but also increased pelvic anterior tilt (mean change ± standard deviation: 23±5°). In most subjects, surgical lengthening of semitendinosus tendon contributed to more extended knee joint angle during static measurements as well as during gait, whereas extensibility of semitendinosus muscle belly was decreased. Post-surgical treatment to maintain muscle belly length and physiological cross-sectional area may improve treatment outcome of medial hamstring lengthening.

A Novel Mobility Device to Improve Walking for a Child With Cerebral Palsy

PURPOSE

To describe the use and outcomes associated with the Upsee in conjunction with Kinesiotape for a child with cerebral palsy.

DESCRIPTIONS

The Upsee and Kinesiotaping were implemented for 24 weeks with a 31-month-old child with cerebral palsy, Gross Motor Function Classification System level III.

OUTCOMES

She progressed from walking with maximal assistance and extensive gait deviations to walking with supervision with a walker on level surfaces with improved gait. Genu recurvatum, heel strike, scissoring, hip extension, foot placement, step length, and stiff knee in swing improved on the basis of videotaped analyses. The Gross Motor Function Measure-66 improved by 11.4.

CONCLUSIONS AND WHAT THIS CASE ADDS

The Upsee is a clinically feasible approach for gait impairments in children through providing increased opportunities for walking while supporting biomechanical alignment. Upsee effectiveness with and without taping is an area for future study.

Testing Gait with Ankle-Foot Orthoses in Children with Cerebral Palsy by Using Functional Mixed-Effects Analysis of Variance

Existing statistical methods extract insufficient information from 3-dimensional gait data, rendering clinical interpretation of impaired movement patterns sub-optimal. We propose an alternative approach based on functional data analysis that may be worthy of exploration. We apply this to gait data analysis using repeated-measurements data from children with cerebral palsy who had been prescribed fixed ankle-foot orthoses as an example. We analyze entire gait curves by means of a new functional F test with comparison to multiple pointwise F tests and also to the traditional method - univariate repeated-measurements analysis of variance of joint angle minima and maxima. The new test maintains the nominal significance level and can be adapted to test hypotheses for specific phases of the gait cycle. The main findings indicate that ankle-foot orthoses exert significant effects on coronal and sagittal plane ankle rotation; and both sagittal and horizontal plane foot rotation. The functional F test provided further information for the stance and swing phases. Differences between the results of the different statistical approaches are discussed, concluding that the novel method has potential utility and is worthy of validation through larger scale patient and clinician engagement to determine whether it is preferable to the traditional approach.

Simulated impacts of ankle foot orthoses on muscle demand and recruitment in typically-developing children and children with cerebral palsy and crouch gait

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.