The effects of dynamic ankle-foot orthoses on functional ambulation activities,weight bearing and spatio-temporal characteristics of hemiparetic gait

Purpose. To investigate the effects of dynamic ankle-foot orthoses (DAFOs) on functional ambulation activities, weight bearing and spatio-temporal characteristics of hemiparetic gait and to inquire whether wearing a DAFO for 3 months has a carryover effect.

Method.?Fourteen chronic hemiparetic patients who could walk independently with or without a cane were the subjects of the study. Patients were assessed initially with tennis shoes and were given custom fabricated DAFOs which they wore for three months and were retested under two conditions: with tennis shoes only and with DAFOs worn in these shoes. All patients were assessed for weight bearing percentage of the affected side, cadence, step length of the involved and uninvolved sides, step width, functional reach, timed up and go, timed down stairs, timed up stairs, physiologic cost index and velocity.

Results.?Comparison of initial and third month assessments with shoes only condition showed that there was no significant improvement for the measured parameters. When comparison was made at the third month while patients were wearing tennis shoes only and when they were wearing DAFO's in their shoes there was a significant difference in favour of the condition where patients were wearing DAFOs.

Conclusion.?The benefits of using DAFOs in chronic hemiparetic patients are lost when the patients are not wearing their orthoses.     

Roll-over shapes of human locomotor systems: effects of walking speed

OBJECTIVE: To examine the hypothesis that roll-over shapes of non-disabled lower limb systems do not change appreciably with walking speed. DESIGN: Repeated measures (n = 24). BACKGROUND: Roll-over shapes of three lower limb systems are presented. They are: roll-over shapes of the (1) foot, (2) ankle-foot, and (3) knee-ankle-foot systems. Roll-over shapes show the effective rocker (or cam) shapes that the lower limb systems conform to during the period in the stance phase of walking between heel contact and opposite heel contact. METHODS: Roll-over shapes were measured by transforming center of pressure data from a laboratory-based coordinate system into each of three body-based coordinate systems. Knee-ankle-foot roll-over shapes were further characterized using a circular arc model. RESULTS: From a statistical standpoint, the radii of the best-fit circular arcs did not change significantly with walking speed, while the forward shifts of the circular models did change significantly. However, the change in forward shift was not considered to be clinically significant. CONCLUSIONS: The biologic systems involved in developing the roll-over shapes adapt to changing conditions of walking speed, including increased loading amplitudes as speed is increased, to maintain similar effective roll-over geometries. RELEVANCE: Roll-over shapes provide insight into the workings of various lower limb systems by taking a new look at existing gait data. This insight could provide broad utility, helping to develop a better understanding of able-bodied and disabled human walking, and leading to the design of improved rehabilitation devices, surgeries, and therapies.     

Effects of adding weight to the torso on roll-over characteristics of walking

Ten participants without physical impairment walked with 0 kg, 11.5 kg, and 23.0 kg of added weight equally distributed about the torso in a harness. At each weight level, the participants walked at slow, normal, and fast self-selected walking speeds. We examined the roll-over characteristics by determining the ankle-foot and knee-ankle-foot roll-over shapes. These shapes, which are the effective rockers created by the respective lower-limb systems between heel contact and opposite heel contact of walking, are found if one transforms the center of pressure of ground reaction force into body coordinate systems. The roll-over shapes of the ankle-foot and knee-ankle-foot systems did not change appreciably with added weight at any of the three walking speeds. The invariance of these biologic systems to added weight should be considered when prostheses and orthoses are designed that intend to replace and augment their function in walking.     

Roll-over shapes of the ankle–foot and knee–ankle–foot systems of able-bodied children

BackgroundThe roll-over shape is the effective rocker shape that a lower limb system conforms to during a step. The roll-over shape concept has been explored in detail in adults and has been successfully used in the design, evaluation, and alignment of lower limb prostheses and orthoses. No such analysis exists for the pediatric population. Therefore, the purpose of this study was to investigate the ankle–foot and knee–ankle–foot roll-over shapes in able-bodied children, values that could serve as tools for design and evaluation of lower limb pediatric prostheses and orthoses.MethodsThis study describes a multi-center retrospective review of existing motion analysis data (n = 153 from three centers). Roll-over shapes were calculated by transforming center of pressure data from a laboratory-based coordinate system into two body-based coordinate systems. Roll-over shapes were then characterized using a circular arc model. Best-fit radii of roll-over shapes for children in three age groups (3–7 years, 8–11 years, and 12–17 years) were compared using the Kruskal–Wallis test.FindingsNo significant changes were found in roll-over shape radii between the three age groups (P = 0.54 for ankle–foot roll-over shape radii; P = 0.12 for knee–ankle–foot roll-over shape radii). The weighted mean of median radii for ankle–foot and knee–ankle–foot roll-over shapes from the three centers were approximately 22% and 17% of body stature, values similar to those seen in adults.InterpretationChildren produce nearly circular knee–ankle–foot roll-over shapes at a young age that are similar to those seen in adults when scaled by body stature.     

Novel passive ankle-foot prosthesis mimics able-bodied ankle angles and ground reaction forces

Background: During gait, the human ankle both bends with ease and provides push-off forces that facilitate forward motion. The ankle is crucial for support, stabilization, and adapting to different slopes and terrains. Individuals with lower limb amputation require an ankle-foot prosthesis for basic mobility.Methods: Inspired by the role of the ankle-foot in an able-bodied gait, the 3D printed Compliant and Articulating Prosthetic Ankle (CAPA) foot was designed. It consists of four articulating components connected by torsion springs and produces forces that are dependent on the ankle angle. Using the Computer Assisted Rehabilitation Environment, able-bodied individuals walked wearing a prosthetic simulator with the Solid Ankle Cushioned Heel foot, Renegade® AT, and multiple versions of the CAPA. These versions test compliant vs. stiff, small vs. large rocker radius, and pretension vs. none. We hypothesized that the CAPA would have larger ankle range of motion, push-off forces, and braking forces.Findings: Compared to existing prostheses, the novel prosthesis exhibits greater and significantly different ankle range of motion and sagittal plane ground reaction forces than existing prostheses during gait. Nine out of ten individuals prefer the novel prosthesis to the existing prostheses, and there is a statistically significant difference in difficulty level ratings.Interpretation: By providing a personalizable and passive alternative to existing designs, the CAPA could improve the quality of life for the growing number of individuals living with limb loss in the United States and around the world.     

穿戴塑料踝足矫形器对下肢肌肉疲劳性的影响

背景：目前尚未见到系统研究踝足矫形器对下肢肌肉影响的文献。目的：提取正常人穿戴固定踝足矫形器时的下肢肌电信号,分析固定踝足矫形器对下肢肌肉疲劳性的影响。方法：选择5名健康男性受试者参加试验,每名受试者分别进行3组试验：①第1组,在不穿戴任何矫形器的情况下以自然步态行走。②第2组,受试者穿戴平跟踝足矫形器以自然步态行走（此时矫形器踝部包裹超过踝中心1 cm,记1.0 cm）,穿戴同一矫形器但在踝部去掉1.0 cm、踝部塑料边缘刚好通过踝中心时采集（记0 cm）,在踝部再去掉1.0 cm后以自然步态行走（记-1.0 cm）。③第3组,受试者穿戴1.5 cm正常跟高踝足矫形器以自然步态行走,穿戴同一矫形器,但跟高分别改为1.0,2.0 cm后以自然步态行走。行走中采用肌电采集仪检测受试者下肢股二头肌、股直肌、胫骨前肌、腓肠肌的表面肌电信号。结果与结论：①正常不穿戴任何矫形器时,4块肌肉的肌电信号是最弱的。②对于任何一块肌肉,正常不穿戴矫形器时所对应肌电值比穿戴不同硬度矫形器时所对应的肌电值要小。③对于股二头肌,正常不穿戴矫形器时所对应的积分肌电值与穿戴正常跟高矫形器时所对应的值很接近,同时这两个值要比穿戴不正常跟高矫形器时所对应的积分肌电值小。表明固定塑料踝足矫形器会引起股二头肌、股直肌、胫骨前肌、腓肠肌的疲劳,当固定塑料踝足矫形器的跟高不合适时会进一步增加股二头肌的疲劳程度。     

Metabolic cost and mechanical work during walking after tibiotalar arthrodesis and the influence of footwear

BackgroundThis study examined metabolic energy cost and external mechanical work for step-to-step transitions after tibiotalar arthrodesis, and the effect of MBT rocker bottom shoes.MethodsOxygen uptake, forceplate and kinematic data were recorded in 18 controls and 15 patients while walking at a fixed speed of 1.25 m/s in three walking conditions: barefoot, normal walking shoes and MBT rocker bottom shoes. Metabolic energy cost, external mechanical work, and the roll-over shape of the ankle–foot complex were analyzed.FindingsTibiotalar arthrodesis leads to higher metabolic energy cost during walking. During step-to-step transitions positive work during push-off with the impaired ankle was decreased but negative work during collision was not affected. The roll-over shape of the ankle–foot complex did not differ between groups and shoe conditions. However, both in patients and controls rocker bottom shoes did lead to decreased positive work at push-off and increased negative work at collision and consequently higher metabolic energy cost of walking.InterpretationExternal mechanical work for step-to-step transitions is not different between patients and controls and could not account for the higher metabolic energy cost in patients. Apparently, patients adopt a different walking strategy that limits step-to-step transition cost but nevertheless induces a higher metabolic energy cost. Despite restricted ankle movement, patients retain a normal roll-over shape of the ankle–foot complex. MBT shoes do not affect roll-over shape and appear to have a counterproductive effect on step-to-step transition cost and walking economy.     

Ankle-foot orthoses in stroke: Effects on functional balance,weight-bearing asymmetry and the contribution of each lower limb to balance control

Background

Ankle-foot orthoses are often provided to improve walking in stroke patients, although the evidence of effects on walking and balance control is still inconsistent. This could be caused by a lack of insight into the influence of orthoses on the underlying impairments. These impairments can be assessed with dual plate posturography to determine the relative contribution of each lower limb to balance control and weight-bearing. This study examined the effects of ankle-foot orthoses on functional balance, static and dynamic weight-bearing asymmetry and dynamic balance control of the paretic and non-paretic lower limbs.

Methods

Twenty stroke subjects (time since stroke 5–127 months) completed the study. Subjects were assessed with and without ankle-foot orthosis. Functional balance was assessed using the Berg Balance Scale, Timed Up & Go test, Timed Balance Test, 10-m walking test and Functional Ambulation Categories. Weight-bearing asymmetry and dynamic balance control were assessed with force plates on a movable platform.

Findings

No significant effects of ankle-foot orthoses were found for weight-bearing asymmetry and dynamic balance control, but significant differences in favour of ankle-foot orthosis use were found for most functional tests.

Interpretation

Although ankle-foot orthoses had no effect on weight-bearing asymmetry or dynamic balance contribution of the paretic lower limb, functional tests were performed significantly better with orthoses. Apparently, improvements at functional level cannot be readily attributed to a greater contribution of the paretic lower limb to weight-bearing or balance control. This finding suggests that ankle-foot orthoses influence compensatory mechanisms.     

Effect of ankle-foot orthoses on gait in typically developing children: Developmental trend in segmental coordination

Objective: As orthoses, and particularly ankle-foot orthoses, are widely used in the management of children with motor disorders, including cerebral palsy, we aimed to study their effect in normal children in order to add to normative gait data, which are essential for diagnosing, understanding and treating abnormal gait patterns. Design: We analyzed the effect of ankle-foot orthoses on classical gait parameters and lower limb segments coordination patterns in typically developing children in two age groups reflecting different neuromaturational/developmental situations. We recorded 3D kinematic gait patterns in 9 children (4-5 years) and 11 children (9-10 years) walking barefoot or wearing bilateral solid ankle-foot orthoses maintaining the ankle joint angle at a neutral position. Results: Ankle-foot orthoses induced little change in cadence, step length, step width or walking velocity in younger children, though they altered intralimb coordination through the gait cycle. In older children, walking velocity was reduced, shank elevation amplitude increased, while lower limb coordination changed less significantly. In this age group, ankle-foot orthoses significantly reduced the variability of coordinative strategies. Conclusion: Ankle-foot orthoses affect the gait pattern in children with a typical development at different levels in younger and older subjects, but the resulting changes are minimal.     

The effect of hinged ankle-foot orthosis on gait and energy expenditure in spastic hemiplegic cerebral palsy

Purpose.?To assess the effectiveness of a hinged ankle-foot orthoses on gait impairments and energy expenditure in children with hemiplegic cerebral palsy (CP) whom orthoses were indicated to control equines.

Method.?Eleven children (seven males, four females) who had a diagnosis of hemiplegic cerebral palsy were included in the study. Each child underwent gait analysis and energy consumption studies with and without ankle-foot orthosis (AFO). The AFOs were all custom-made for the individual child and had plantarflexion stop at 0° with no dorsoflexion stop. The Vicon 512 Motion analysis system was used for gait analysis. Walking energy expenditure measurements were done with breath by breath method using an open-circuit indirect calorimeter (Vmax 29c, Sensormedics, USA). All tests were carried out on the same day with enough resting period.

Results.?AFO application, as compared with the barefoot condition improved walking speed, stride length and single support time. Double support time was decreased significantly with AFOs and no change in cadance. Ankle dorsiflexion at initial contact, midstance and midswing showed significiant increase. Knee flexion at initial contact was decreased and no significant change in maximum knee extension at stance and maximum knee flexion at swing was obtained. The oxygen consumption was significantly reduced during AFO walking.

Conclusion.?The hinged AFO is useful in controlling dynamic equinus deformity and reducing the energy expenditure of gait in children with hemiplegic spastic cerebral palsy.     

Determining asymmetry of roll-over shapes in prosthetic walking

How does the inherent asymmetry of the locomotor system in people with lower-limb amputation affect the ankle-foot roll-over shape of prosthetic walking? In a single-case design, we evaluated the walking patterns of six people with lower-limb amputation (3 transtibial and 3 transfemoral) and three matched nondisabled controls. We analyzed the walking patterns in terms of roll-over characteristics and spatial and temporal factors. We determined the level of asymmetry by roll-over shape comparison (root-mean-square distance) as well as differences in radius of curvature. In addition, we calculated ratios to determine spatial and temporal asymmetries and described different aspects of asymmetry of roll-over shapes. All participants showed some level of asymmetry in roll-over shape, even the nondisabled controls. Furthermore, we found good intralimb reproducibility for the group as a whole. With respect to spatial and temporal factors, the participants with transtibial amputation had a quite symmetrical gait pattern, while the gait in the participants with transfemoral amputation was more asymmetrical. The individual ankle-foot roll-over shapes provide additional insight into the marked individual adjustments occurring during the stance phase of the nondisabled limb. The two methods we present are suitable for determining asymmetry of roll-over shapes; both methods should be used complementarily.     

Effects of shoe heel height on biologic rollover characteristics during walking

This study investigated the effects of shoe heel height on the rollover characteristics of the biologic ankle-foot system. Ten nondisabled adult female volunteers walked using three pairs of shoes with varying heel heights and at three walking speeds with each pair of shoes. Kinematic and kinetic data needed to calculate the rollover shapes of the ankle-foot systems of the participants were collected. Rollover shapes are the effective rocker geometries that ankle-foot systems conform to between heel contact and opposite heel contact. Parameters of the best-fit circular arcs to the rollover shapes were used in an examination of the effects of shoe heel height on the ankle-foot system. The results support the notion that nondisabled humans automatically adapt their ankle-foot systems to accommodate a range of shoe heel heights, resulting in rollover shapes that do not change appreciably. Given physiologic constraints, this adaptation may not be possible for very high heels.     

Presentation 5: An investigation of foot alignment and support in ankle foot orthoses

Objective: To investigate the effect that ankle-foot alignment and foot support in ankle-foot orthoses (AFOs) may have on the gait of subjects with hemiplegia after stroke. Design: Test-retest. Setting: Motion analysis research laboratory. Participants: 20 participants with hemiplegia. Intervention: Subjects underwent 3 gait analyses, each 2 weeks apart. The first tested walking with a conventionally aligned AFO; the second tested walking with a heel-height compensated AFO with full-length footplate; and the third tested walking with a heel-height compensated AFO with three-quarter length footplate. Main Outcome Measures: We acquired bilateral kinematic, kinetic, electromyographic, and plantar pressure data, as well as subjective information from the subjects using a questionnaire. Results: Preliminary data from 7 subjects suggests that, compared with a shoes-only condition, all AFO conditions improved ankle position at initial contact and in swing, and, where knee hyperextension was present, reduced the onset and magnitude of the hyperextension. All AFO conditions also changed the internal knee moment from flexor to extensor, decreased the heel strike transient present in the vertical ground reaction force, and improved roll-over shape. Conclusions: Compared with the full length AFOs, the three-quarter length AFO provided the shortest roll-over shape and had the highest peak pressures in the midfoot. We believe that this study will give us a better understanding of the effect of ankle-foot alignment and foot support on hemiplegic gait, and may enable us to recommend more appropriate AFO designs.     

Physiological cost index (PCI) and walking performance in individuals with transfemoral prostheses compared to healthy controls

Purpose.?Uncomplicated methods for evaluation of prosthetic walking performance for individuals with lower limb amputations are valuable. The Physiological Cost Index (PCI), the comfortable walking speed (CWS) and self-reported walking distances are three examples of such measures. The aim was to obtain values for these measures for individuals walking with transfemoral prostheses and to compare the results with healthy controls.

Method.?Individuals with an established transfemoral amputation for reasons other than vascular disease (TFA-group, n = 41, 30 male/11 female, mean age 49, SD 11.5) were compared to age-and gender matched healthy controls (Healthy group, n = 22). PCI was assessed walking in CWS for 5 min and self-reported distances accomplished outdoors was assessed with the Walking Habit Score (0 – 100).

Results.?Mean PCI was 0.55 (SD 0.19) in the TFA-group and 0.31 (SD 0.09) in the Healthy group (p < 0.001). The CWS was 62 (SD 12.6) and 90 (SD 12.8) m/min and the Walking Habit Score 48 (SD 19) and 74 (SD 16) score-points respectively (p < 0.001).

Conclusions.?By using uncomplicated and inexpensive methods, this study shows that walking with transfemoral prostheses is done with considerably increased energy cost, slower CWS and that limited walking distances outdoors are performed compared to healthy controls.     

Effect of foot orthoses on lower limb muscle activation: a critical review

Abstract

Foot orthoses can be a valuable component of musculoskeletal rehabilitation, improving lower limb alignment, controlling motion and providing shock absorbency. Recent evidence suggests foot orthoses may also have a significant effect on lower limb muscle activation in young, healthy adults. This review examines the evidence for changes in muscle activation patterns when wearing orthoses, and explores the proposed mechanisms by which foot orthoses may bring about changes in lower limb muscle activity. Based on the current results it is proposed that different mechanisms may occur by which orthoses affect muscle activity, due to their differing construction and design.     

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

BackgroundMany 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.MethodsTwelve 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.FindingsPeak 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.InterpretationA 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.     

Evaluation of the performance of paraplegic subjects during walking with a new design of reciprocal gait orthosis

Background: Spinal cord injury (SCI) influences a person's ability to stand and walk. Various orthoses have been developed to solve these standing and walking problems, however, patients still experience high energy consumption during walking and high forces on the upper limbs. A new reciprocal gait orthosis (RGO) was designed to address these problems. The aim of this study was to evaluate the performance of the new orthosis design with paraplegic subjects. Method: Three paraplegic subjects with the lesion at level T12 and three able-bodied subjects were included in this study. Hip and pelvis range of motion and vertical ground reaction force were evaluated using the Qualysis motion analyzer system and a Kistler force plate. Energy consumption was measured with the Polar heart rate monitoring system. The differences between SCI individuals when walking with a Knee Ankle Foot Orthosis (KAFO) and the new RGO, and the differences between able-bodied and paraplegic subjects were evaluated by the use of paired sample and two sample t test, respectively. Result: The results showed that energy consumption and gait analysis outcomes with new RGO orthosis were better than the KAFO. However, there was a large difference between paraplegic and able-bodied subjects while walking with the new orthosis. Conclusion: The new RGO design performed better than a KAFO in terms of energy consumption, walking style and vertical ground reaction force. Therefore, it appears that RGO may be a useful orthosis for patients with paraplegia.

• Implications for Rehabilitation

• Walking and standing of the subjects with spinal cord injury (SCI) improve their physiological and physiological health.

• This study introduces a new type of orthosis design in order to improve the abilities of SCI subjects during walking and standing.

• It seems that the new design works better than available orthoses (KAFO).