Push-off Power Research Articles

Energy storing and return prosthetic feet improve step length symmetry while preserving margins of stability in persons with transtibial amputation

BackgroundEnergy storing and return (ESAR) feet are generally preferred over solid ankle cushioned heel (SACH) feet by people with a lower limb amputation. While ESAR feet have been shown to have only limited effect on gait economy, other functional benefits should account for this preference. A simple biomechanical model suggests that enhanced gait stability and gait symmetry could prove to explain part of the difference in the subjective preference between both feet.AimTo investigate whether increased push-off power with ESAR feet increases center of mass velocity at push off and enhance intact step length and step length symmetry while preserving the margin of stability during walking in people with a transtibial prosthesis.MethodsFifteen people with a unilateral transtibial amputation walked with their prescribed ESAR foot and a SACH foot at a fixed walking speed (1.2 m/s) over a level walkway while kinematic and kinetic data were collected. Push-off work generated by the foot, center of mass velocity, step length, step length symmetry and backward margin of stability were assessed and compared between feet.ResultsPush-off work was significantly higher when using the ESAR foot compared to the SACH foot. Simultaneously, center of mass velocity at toe-off was higher with ESAR compared to SACH, and intact step length and step length symmetry increased without reducing the backward margin of stability.ConclusionCompared to the SACH foot, the ESAR foot allowed an improvement of step length symmetry while preserving the backward margin of stability at community ambulation speed. These benefits may possibly contribute to the subjective preference for ESAR feet in people with a lower limb amputation.

How do children with bilateral spastic cerebral palsy manage walking on inclines?

BackgroundWalking on inclined surfaces is an everyday task, which challenges stability and propulsion even in healthy adults. Children with cerebral palsy adapt similarly to inclines like healthy children do. However, how stability and propulsion in these subjects are influenced by different inclines remained unaddressed as of yet. Research questionThe aim was to examine the feeling of safety, stability and propulsion of children with cerebral palsy when walking on inclines to gain insight into the challenges they might face on these conditions. MethodsEighteen children with bilateral spastic cerebral palsy with gross motor function classification scale level I and II and nineteen healthy children underwent instrumented 3D gait analysis on level ground and on a 5° and a 10° incline. A mixed linear model was used to draw between and within group comparisons. ResultsReduced lateral trunk sway, a relative lengthening of the lower limb at initial contact and a controlled walking speed were employed during downhill gait compared to level walking. Patients showed an increased sagittal ROM of trunk (3–4°) and pelvis (2–3°) and a decreased sagittal knee ROM (13°) compared to the typically developed children. During uphill gait, an insufficient increase of push-off power at the ankle (increase by 0.48 W/kg) was noted in children with CP, which appeared to lead to particularly shorter strides (about 0.1 m) in patients compared to healthy children (increase by 1.32 W/kg). SignificanceDepending on inclination angle, children with cerebral palsy managed to walk on inclines in a controlled manner. The steeper the incline, the more the gait appeared to be affected: decreased feeling of safety, increased need for stabilising mechanisms for downhill gait and less sufficient uphill propulsion were seen. Helping these patients to attain better control during downhill gait and strengthening uphill gait mechanisms may support their participation in everyday life.

Does Ankle Muscle Performance Mirror Improved Pain Following Total Ankle Arthroplasty?

Category: Ankle Arthritis Introduction/Purpose: Total ankle arthroplasty (TAA) outcomes include pain reduction and improved gait speed. Ankle push off power, which requires gastroc-soleus muscle strength, is a critical aspect of healthy gait and increases as gait speed increases. It appears that improvements in pain translate to improved ankle muscle performance. However, ankle power after TAA is surprisingly low. It is possible years of arthritis and latent muscle memory result in reduced gastroc-soleus muscle strength and a gait pattern reliant on proximal joints for power. Evaluating these hypotheses will drive postoperative care. The purpose of this ongoing prospective study is to be the first to evaluate the interplay of pain, gait speed, and ankle muscle performance (strength and power) in people following TAA for end-stage ankle arthritis. Methods: Twelve people [Mean (SD): Age 61 (14.3) years; BMI 30.0 (5.4) Kg/m2; 83% male] with end-stage ankle arthritis who were candidates for TAA participated (12 preoperative and 9 six-month postoperative visits). Performance of adjunct soft tissue procedures and postoperative care were patient specific. A twenty point numeric pain rating scale was used to measure worst pain in the past week. Three dimensional multi-segment foot motion analysis was performed while participants walked barefoot on level ground over a force plate. Ankle peak push-off power (joint torque x segmental velocity) was calculated. Ankle peak isokinetic plantarflexion strength (torque at 60 degrees / second) and ankle sagittal plane passive range of motion were measured with a dynamometer. Participants also completed the six minute walk test. Wilcoxon Signed Rank tests were used to evaluate preoperative to postoperative changes and between limb differences postoperatively. Results: Pain decreased (postoperative mean = 2.8; p = 0.01) and gait speed increased following TAA (p = 0.02). Ankle plantarflexion strength and ankle power during walking were preserved following TAA (both p > 0.8) (Figure 1). Postoperative group mean dorsiflexion was 25.1 degrees and plantarflexion was 18.9 degrees, suggesting sufficient ankle motion was present for plantarflexor muscle performance. However, between limb differences were significant for both strength and power (both p < 0.05) postoperatively. The involved ankle produced 36% less strength and generated 45% less power during walking in comparison to the uninvolved limb. This asymmetry demonstrates that involved limb ankle muscle performance was not normalized at six-month follow up, despite improvements in pain. Conclusion: Study findings provide preliminary evidence that improved pain and gait speed are disconnected from ankle muscle performance following TAA. Postoperative improvements in gait speed were likely driven by more proximal joints (i.e. hip). Without additional targeted postoperative plantarflexion strengthening and gait training to improve ankle muscle involvement, gains in ankle power, a symmetrical gait pattern, and patient tolerance to higher level activity (i.e. stairs) are unlikely to occur long-term. The underpinning mechanisms limiting the necessary strength to drive power generation (i.e. length-tension relationship, atrophy), and the possible cumulative effect of how abnormal gait may influence implant survivorship deserve further attention.

The Midfoot Contributes to Power and Work During Single-limb Heel Rise

Category: Midfoot/Forefoot Introduction/Purpose: Single-limb heel rise (HR) is used to evaluate muscle performance and clinical outcomes in people with foot and ankle pathology. While the midfoot contributes 13% of total foot/ankle work to forward propulsion during gait, healthy HR performance remains primarily characterized by ankle function. Similar to its function during gait, the midfoot may also generate power during HR to provide the stability needed for ankle push-off power. Further characterization of HR performance by evaluating midfoot kinetics may advance understanding of foot function in the clinical application of the HR task. The purpose of this study was to examine ankle and midfoot power and work during single-limb HR in healthy adults. Methods: Twelve healthy adults [Mean (SD): Age 31.3 (4.9) years; BMI 25.2 (3.3) Kg/m2; 50% male] performed twenty barefoot single-limb heel rises. Multi-segment kinematic and ground reaction force data were recorded with an electromagnetic motion capture system and force plate. Subject-specific, three segment foot models (tibia, rearfoot, forefoot) were derived. Inverse dynamic calculations were performed to obtain ankle and midfoot peak positive and negative powers (joint torque x segmental velocity), as well as the timing of peak powers (% of the heel rise). Midfoot work (integral of power with respect to time), reflecting energy production, was examined as a percentage of the entire work performed at the ankle and midfoot during HR. Group descriptive data were examined as mean (standard deviation) [95% confidence interval]. Results: Ankle peak positive power was 2.8 (0.8) [2.2 - 3.3] W/Kg and occurred during the ascent phase at 7% HR (Figure 1). Midfoot peak positive power was 0.5 (0.2) [0.3 - 0.6] W/Kg occurring at 6%. Ankle peak negative power was 2.1 (0.6) [1.7 - 2.4] W/Kg and occurred during the descent phase at 84% HR. Midfoot peak negative power was 0.4 (0.2) [0.2 - 0.5] W/Kg occurring at 83%. The proportion of midfoot work to total work performed was 13.5 (5.7) [9.8 - 17.1] %. Conclusion: Study findings advance understanding of foot function by demonstrating the contribution of midfoot power and work during HR in healthy adults. Midfoot peak powers were approximately 18% of ankle powers and occurred at similar times during HR. Further, midfoot energy production appears to be an important aspect of healthy HR performance because approximately 14% of the total foot/ankle work occurs at the midfoot. Since active internal muscle and ligament mechanisms are attributed to midfoot power generation, practitioners should consider midfoot tissue loading and muscle performance when implementing the HR task in clinical practice.

Midfoot power during walking and stair ascent in healthy adults

Category: Midfoot/Forefoot Introduction/Purpose: Intrinsic foot muscles have the capacity to attenuate and reverse arch deformation under loaded conditions. This function is proposed to be an important component in generating the midfoot power and stability requisite for gastroc-soleus muscle action at the ankle during forward propulsion. Synergistic activation of intrinsic foot muscles is proposed to function as a ‘foot core’ during weightbearing activity that is analogous to the function of the smaller muscles at the spine. If this theory were sound, midfoot power would be expected to increase, potentially in proportion to ankle power, as the muscular demand of a task increases. The purpose of this study was to explore the nature and behavior of midfoot and ankle power during walking and stair ascent in healthy adults. Methods: Twelve healthy adults [Mean (SD): Age 31.3 (4.9) years; BMI 25.2 (3.4) Kg/m2; 50% female] walked, ascended a standard step, and ascended a high step. An electromagnetic sensor motion capture system and force plate were used to record multi-segment foot motion and ground reaction force data. Subject-specific three segment foot models (tibia, rearfoot, forefoot) were derived. Inverse dynamic calculations were performed to obtain ankle and midfoot positive total power. Positive total power, calculated as the sum of positive power (joint torque x segmental velocity) after heel off, reflects the entire amount of ankle or midfoot push-off power generated for a given task. The proportion of midfoot to ankle positive total power was also calculated. Multiple one-way repeated measures ANOVAs were conducted to evaluate differences in power variables across tasks. Bonferroni adjusted pairwise comparisons were made to assess differences in main effects. Effect sizes between conditions were also examined (Cohen’s d). Results: Significant main effects were found for both ankle and midfoot positive total power [ankle F = 29.8 (p < 0.01); midfoot F = 63.1 (p < 0.01)]. Pairwise comparisons revealed that total power significantly increased across each activity at both the ankle (d range: 0.09 - 2.3) and midfoot (d range: 1.4 - 2.9) [all p < 0.05]. Interestingly, a main effect was not observed in the proportion of midfoot to ankle total power across activity [F = 1.2 (p = 0.33)] (Figure 1). Conclusion: The findings of this study provide preliminary support for the idea of a midfoot ‘foot core’ system. While increased ankle and midfoot power is required as the muscular demand of activity increases from walking to standard step and high step ascent, the proportion of midfoot to ankle total power remains the same. Study findings may assist practitioner understanding in addressing regional foot muscle imbalances and advancing patients to higher-level functional activities.

Combining Push-Off Power and Nonlinear Damping Behaviors for a Lightweight Motor-Driven Transtibial Prosthesis

Transtibial prostheses play an important role in below-knee amputees’ daily activities. Our previous study presented a lightweight prosthesis with damping behaviors, which can adapt to different terrains. However, the proposed prosthesis cannot provide push-off during the stance phase. In this paper, we redesigned the mechanical structure, combining push-off and damping behaviors. The Peking University Robotic Trantibial Prosthesis (PKU-RoboTPro-) II makes a trade-off between push-off power and lightweight. Three unilateral transtibial subjects participated in the study. Gait symmetry and metabolic cost of walking with the proposed prosthesis were evaluated under conditions of three terrains and four walking speeds. The gait symmetry of the subjects using the prosthesis combining push-off and damping behaviors in stance time and ground reaction force distribution are improved. Meanwhile, the PKU-RoboTPro-II with a push-off mode can reduce energy expenditure, with an average 14% $\pm$ 8% reduction and a maximal 31% reduction under different conditions, compared with a non-push-off mode. When the weight of the lithium-ion rechargeable battery is 0.28 kg (2.6 Ah), it enables the new prosthesis combining push-off and damping behaviors to walk approximately 10 000 strides, on average.

Gait performance and foot pressure distribution during wearable robot-assisted gait in elderly adults

BackgroundA robotic exoskeleton device is an intelligent system designed to improve gait performance and quality of life for the wearer. Robotic technology has developed rapidly in recent years, and several robot-assisted gait devices were developed to enhance gait function and activities of daily living in elderly adults and patients with gait disorders. In this study, we investigated the effects of the Gait-enhancing Mechatronic System (GEMS), a new wearable robotic hip-assist device developed by Samsung Electronics Co, Ltd., Korea, on gait performance and foot pressure distribution in elderly adults.MethodsThirty elderly adults who had no neurological or musculoskeletal abnormalities affecting gait participated in this study. A three-dimensional (3D) motion capture system, surface electromyography and the F-Scan system were used to collect data on spatiotemporal gait parameters, muscle activity and foot pressure distribution under three conditions: free gait without robot assistance (FG), robot-assisted gait with zero torque (RAG-Z) and robot-assisted gait (RAG).ResultsWe found increased gait speed, cadence, stride length and single support time in the RAG condition. Reduced rectus femoris and medial gastrocnemius muscle activity throughout the terminal stance phase and reduced effort of the medial gastrocnemius muscle throughout the pre-swing phase were also observed in the RAG condition. In addition, walking with the assistance of GEMS resulted in a significant increase in foot pressure distribution, specifically in maximum force and peak pressure of the total foot, medial masks, anterior masks and posterior masks.ConclusionThe results of the present study reveal that GEMS may present an alternative way of restoring age-related changes in gait such as gait instability with muscle weakness, reduced step force and lower foot pressure in elderly adults. In addition, GEMS improved gait performance by improving push-off power and walking speed and reducing muscle activity in the lower extremities.Trial registrationNCT02843828.

Lower-extremity dynamics of walking in neuropathic diabetic patients who wear a forefoot-offloading shoe

BackgroundA forefoot-offloading shoes has a negative-heel rocker outsole and is used to treat diabetic plantar forefoot ulcers, but its mechanisms of action and their association with offloading and gait stability are not sufficiently clear. MethodsTen neuropathic diabetic patients were tested in a forefoot-offloading shoe and subsequently in a control shoe with no specific offloading construction, both worn on the right foot (control shoe on left), while walking at 1.2m/s. 3D-instrumented gait analysis and simultaneous in-shoe plantar pressure measurements were used to explain the shoe's offloading efficacy and to define centre-of-pressure profiles and left-to-right symmetry in ankle joint dynamics (0–1, 1:maximum symmetry), as indicators for gait stability. FindingsCompared to the control shoe, peak forefoot pressures, vertical ground reaction force, plantar flexion angle, and ankle joint moment, all in terminal stance, and the proximal-to-distal centre-of-pressure trajectory were significantly reduced in the forefoot-offloading shoe (P<0.01). Peak ankle joint power was 51% lower in the forefoot-offloading shoe compared to the control shoe: 1.61 (0.35) versus 3.30 (0.84) W/kg (mean (SD), P<0.001), and was significantly associated with forefoot peak pressure (R2=0.72, P<0.001). Left-to-right symmetry in the forefoot-offloading shoe was 0.39 for peak ankle joint power. InterpretationBy virtue to their negative-heel rocker-outsole design, forefoot-offloading shoes significantly alter a neuropathic diabetic patient's gait towards a reduced push-off power that explains the shoe's offloading efficacy. However, gait symmetry and stability are compromised, and may be factors in the low perceived walking discomfort and limited use of these shoes in clinical practice. Shoe modifications (e.g. less negative heel, a more cushioning insole) may resolve this trade-off between efficacy and usability.

Correlation of Functional Measures of Mobility with Patient-Reported Outcomes after Total Ankle Arthroplasty

Category: Ankle Introduction/Purpose: Patients undergoing total ankle arthroplasty (TAA) have a proven track record of clinical improvements in subjective patient-reported outcome measures (PROMs) and objective measures with three dimensional gait analysis. Each represents a valid, but different kind of information, and both are important. What is unknown is whether and how objective improvements as measured by gait analysis correlate with the improvements measured by PROMs. The goal of this study was to investigate the correlation between objective function and PROMs in patients undergoing TAA. Methods: Seventy-six patients (28m/48f) aged 61 (37-79) with a mean BMI of 29.60 (19.63-46.64) and greater than 1-year follow-up underwent preoperative and postoperative gait analysis. Temporal-spatial, kinematic, and kinetic parameters of gait were recorded. Patients also completed AOFAS Ankle/Hindfoot scores, visual analog score for pain (VAS), and the MOS 36-Item Short-Form Health Survey (SF-36) questionnaires within two weeks of their preoperative gait analysis and at the one-year postoperative gait analysis. A t-test for dependent means was used to compare preoperative and postoperative outcomes. Additionally, a Pearson correlation coefficient was utilized to measure the strength of association between parameters of gait and PROMs. A p-value of &lt; 0.05 was considered to be statistically significant. Results: Gait Analysis: Patients had a statistically significant improvement in all temporal-spatial parameters of gait, in total range of motion, mean maximum plantarflexion, and ankle power. Patient-reported outcome measures: A statistically significant and clinically meaningful significant improvement was detected for AOFAS score, VAS score, and SF-36-Physical score. Changes in the SF-36-Mental score were not detected to be statistically significant or clinically significant. Correlation: The AOFAS score had a moderate positive correlation with preoperative walking-speed, step-length and ankle-power, postoperative walking-speed, step-length and ankle-power, and improvement in walking-speed, cadence, and ankle-power. The SF-36-Physical score had a weak to moderate positive correlation with preoperative walking speed, step length, and ankle power and postoperative walking speed, step length and ankle power. No correlation between VAS or SF-36-Mental score and function could be detected. Conclusion: There is a moderate correlation with AOFAS and SF-36-Physical scores between walking speed (temporal-spatial parameters), and ankle push-off power (kinetic parameters). PROMs did not correlate with improvements in ROM (kinematic parameters). This may challenge the assumption that preservation of motion is the most important role of TAA. The data may be interpreted to mean cadence, walking-speed, step-length and ankle power are the most important aspects of gait with respect to patients’ perceived outcomes. However, perhaps ROM is important to patient satisfaction – but the outcome measures we use are not sufficiently sensitive/specific to measure the effect of improved or maintained motion.

Medial gastrocnemius and soleus muscle-tendon unit, fascicle, and tendon interaction during walking in children with cerebral palsy.

This study investigates the invivo function of the medial gastrocnemius and soleus muscle-tendon units (MTU), fascicles, and tendons during walking in children with cerebral palsy (CP) and an equinus gait pattern. Fourteen children with CP (9 males, 5 females; mean age 10y 6mo, standard deviation [SD] 2y 11mo; GMFCS level I=8, II=6), and 10 typically developing (6 males, 4females; mean age 10y, SD 2y 1mo) undertook full body 3D gait analysis and simultaneous B-mode ultrasound images of the medial gastrocnemius and soleus fascicles during level walking. Fascicle lengths were analysed using a semi-automated tracking algorithm and MTUs using OpenSim. Statistical parametric mapping (two-sample t-test) was used to compare differences between groups (p<0.05). In the CP group medial gastrocnemius fascicles lengthened during mid-stance gait and remained longer into late-stance compared to the typically developing group (p<0.001). CP medial gastrocnemius fascicles shortened less during stance (1.16mm [SD 1.47mm]) compared to the typically developing group (4.48mm [SD 1.94mm], p<0.001). In the CP group the medial gastrocnemius and soleus MTU and tendon were longer during early- and mid-stance (p<0.001). Ankle power during push-off (p=0.015) and positive work (p<0.002) and net work (p<0.001) were significantly lower in the CP group. Eccentric action of the CP medial gastrocnemius muscle fascicles during mid-stance walking is consistent with reduced volume and neuromuscular control of impaired muscle. Reduced ankle push-off power and positive work in the children with CP may be attributed to reduced active medial gastrocnemius fascicle shortening. These findings suggest a reliance on passive force generation for forward propulsion during equinus gait.

Management of Hallux Rigidus in Athletes

Hallux rigidus can be a major limiting factor for athletes due to pain, stiffness, and weakness. Any sporting activity that requires significant dorsiflexion of the hallux to perform at peak level will be negatively impacted by a painful stiff toe due to limited push-off strength and propulsive power. There are reasonably good nonsurgical options to help an athlete to extend their activities and career, and should be exhausted before indicating for surgery. Once nonoperative measures are no longer able to meet the satisfaction of the patient, several surgical options are available. The surgical choice depends upon the grade of disease and expectations of the athlete. In running sports, the initial goal is always to increase and maintain range of motion, while reducing pain. This is easier to achieve in early stages of hallux rigidus. In later stages of hallux rigidus, it might be possible to increase range of motion, but the underlying degenerative changes of the joint might continue to cause pain with activities. An arthrodesis is the most reliable way to achieve pain relief, but will also have most impact on the ability to play certain sports.

A New Development of Powered Orthotic for Deficient Push-Off Power

A New Development of Powered Orthotic for Deficient Push-Off Power

Energy flow analysis of amputee walking shows a proximally-directed transfer of energy in intact limbs, compared to a distally-directed transfer in prosthetic limbs at push-off

Reduced capacity and increased metabolic cost of walking occurs in amputees, despite advances in prosthetic componentry. Joint powers can quantify deficiencies in prosthetic gait, but do not reveal how energy is exchanged between limb segments. This study aimed to quantify these energy exchanges during amputee walking.Optical motion and forceplate data collected during walking at a self-selected speed for cohorts of 10 controls, 10 unilateral trans-tibial, 10 unilateral trans-femoral and 10 bilateral trans-femoral amputees were used to determine the energy exchanges between lower limb segments.At push-off, consistent thigh and shank segment powers were observed between amputee groups (1.12W/kg vs. 1.05W/kg for intact limbs and 0.97W/kg vs. 0.99W/kg for prosthetic limbs), and reduced prosthetic ankle power, particularly in trans-femoral amputees (3.12W/kg vs. 0.87W/kg). Proximally-directed energy exchange was observed in the intact limbs of amputees and controls, while prosthetic limbs displayed distally-directed energy exchanges at the knee and hip.This study used energy flow analysis to show a reversal in the direction in which energy is exchanged between prosthetic limb segments at push-off. This reversal was required to provide sufficient energy to propel the limb segments and is likely a direct result of the lack of push-off power at the prosthetic ankle, particularly in trans-femoral amputees, and leads to their increased metabolic cost of walking.

Metabolic cost of level-ground walking with a robotic transtibial prosthesis combining push-off power and nonlinear damping behaviors: preliminary results.

Recent advances in robotic technology are facilitating the development of robotic prostheses. Our previous studies proposed a lightweight robotic transtibial prosthesis with a damping control strategy. To improve the performance of power assistance, in this paper, we redesign the prosthesis and improve the control strategy by supplying extra push-off power. A male transtibial amputee subject volunteered to participate in the study. Preliminary experimental results show that the proposed prosthesis with push-off control improves energy expenditure by a percentage ranged from 9.72 % to 14.99 % for level-ground walking compared with the one using non-push-off control.

The Relationship Between Gait, Gross Motor Function, and Parental Perceived Outcome in Children With Clubfeet.

Assessment of children treated nonoperatively for idiopathic clubfoot, has primarily focused on the kinematic and kinetic results measured with gait analysis (GA). Excellent results in ankle motion and push-off power during gait have been reported at age 5; however, the assessment of gross motor function, has not been evaluated. The purpose of this study was to look at the relationship between gait measures, Peabody Developmental Motor Scales and parent-perception of their child's outcome [measured with the Pediatric Outcomes Data Collection Instrument (PODCI)]. A total of 81 children with idiopathic clubfoot were seen for both GA and Peabody testing. Children who initially underwent the Ponseti technique (n=29), the French Physical Therapy method (PT) (n=23), and a group of children initially treated nonoperatively, but who required surgical intervention before GA at 5 years of age (n=29) were enrolled. Pearson's correlation coefficient was used to establish significant relationships between gait variables, Peabody, and PODCI scores. Gait data showed that the Ponseti treated feet had significantly greater ankle power than feet treated surgically (P=0.0075). The Peabody results showed that the PT feet had higher stationary (P=0.0332) and overall gross motor quotient percent (GMQ%) scores (P=0.0092) than the surgical feet. No differences were found in PODCI scores. Ankle power was weakly correlated to the GMQ% (r=0.29; P=0.0102); however, the GMQ% showed a strong correlation to the parent report of Global Functioning Scale on the PODCI (r=0.48; P=0.0005). Minimal gait disturbances do not interfere with function or parental assessment of abilities and satisfaction at 5-year follow-up in children with idiopathic clubfeet. Nonoperative correction of clubfeet should be the goal when possible, as the Peabody scores show better function as early as 5 years of age when surgery is not required.

EFFECT OF KINETIC RETURN ANKLE FOOT ORTHOSIS IN PATIENT WITH INCOMPLETE SPINAL CORD INJURY: CHANGES OF THE GAIT PATTERN. A CASE REPORT

Background. The variety of orthotics available induces a purpose for estimation of their influence of functional mobility for individual needs in people with incomplete spinal cord injuries (ISCI). The aim of the study was to investigate the effect of the use of kinetic return ankle foot orthosis (KRAFO) on gait pattern in case of ISCI. Methods. Ankle and knee joint kinematic and kinetic characteristics during gait with and without KRAFO were studied in a 34-year-old man with ISCI (fracture v.C5) using 3D motion analysis system (Vicon Motion Systems Ltd., UK) including two dynamographic platforms (AMTI, USA). Ankle and knee joint angles at initial contact and mid-stance, ankle dorsiflexion and foot progression angle in swing phase and ankle joint push-off values in stance phase were analysed. Results. An excessive dorsiflexion in right ankle joint at initial contact, in mid-stance and in swing-phase occurred when walking without the orthosis, which decreased (105, 57 and 73%, respectively, p &lt; .01) with the use of KRAFO. Orthoses use evoked the decrease (77%, p &lt; .01) in peak foot progression angle. Ankle joint peak push- off power was low without the use of KRAFO and decreased even more (28%, p &lt; .05) with the use of orthosis. Decreases of knee joint flexion angle at initial contact and in mid-stance (29 and 23%, respectively) with the use of KRAFO were not significant as compared to gait without orthosis. Conclusions. Walking with KRAFO improved ankle and knee joint stability, providing a decrease in ankle kinematic characteristics but ankle joint push-off power did not change. Further studies are needed to compare the effect of KRAFO in comparison with other orthoses on gait pattern in case of ISCI in accordance with the patient- centric approach for rehabilitation process management.

Transtibial amputee gait efficiency: Energy storage and return versus solid ankle cushioned heel prosthetic feet.

Energy storage and return (ESR) feet have long been assumed to promote metabolically efficient amputee gait. However, despite being prescribed for approximately 30 yr, there is limited evidence that they achieve this desired function. Here, we report a meta-analysis of data from 10 studies that met our selection criteria to determine whether amputee walking with ESR feet is more efficient than with conventional solid ankle cushioned heel (SACH) feet. Additionally, the data were tested for a relationship with walking speed since it has been suggested ESR feet might perform better at higher speeds. The raw data are highly variable because of differences in study protocols; therefore, we normalized the data and found a statistically significant difference (p < 0.001) between ESR and SACH feet. However, the magnitude of this difference is small, with the cost of transport (COT) with ESR feet being 97.3% of the cost with SACH feet. No relationship between ESR COT and speed was found (p = 0.19). We hypothesize that the small but statistically significant difference between ESR and SACH feet may not constitute a functionally significant improvement in COT, possibly related to the limited push-off power provided by ESR feed compared with nondisabled ankles.

Effects of gastrocnemius recession on ankle motion, strength, and functional outcomes: a systematic review and national healthcare database analysis.

The purpose of this systematic review was to report the effects of gastrocnemius recession on ankle dorsiflexion range of motion, function, and push-off power. The MEDLINE and EMBASE databases were reviewed with terms "gastrocnemius recession". The inclusion criteria were: (1) clinical studies, (2) published in a peer-reviewed journal within the past 10 years, and (3) published in English. Excluded were: (1) review articles, (2) cadaveric studies, (3) studies including patients under the age of 18 years, (4) studies evaluating a neurologic condition, (5) level of evidence 5, and (6) Quality of Evidence Score <3. Data were then extracted and analysed for trends. The PearlDiver Database was also used to review de-identified patient information retrospectively between 2007 and 2011. Full-text review yielded 23 articles that fit the inclusion criteria. Twenty-one of 23 (91%) and 2/23 (9%) studies were level of evidence 4 and 3, respectively. Twelve of 23 (52%) studies reported follow-up assessment between 12 and 36 months, and no studies reported longer-term follow-up. Twelve of 12 (100%) studies reported improved dorsiflexion range of motion 9/9 (100%) reported improved AOFAS, and 11/11 (100%) reported improved VAS. Five of 23 (22%) studies reported strength in a measured and controlled fashion with variable results, but of these, no study reported a return to normal power. The mean complication rate was 14%. The available evidence supports that GR improves functional outcomes and increases dorsiflexion range of motion. Furthermore, GR affects gait kinematics, which may cause compensatory effects at the knee, ankle, and subtalar joints. Evidence has shown that power does not return to normal levels. Clinicians may utilize these data clinically to determine whether patients may benefit from GR or not. IV.

Abstract 289: Abnormal Gait Pattern at Comfortable and Fast Walking Speed in Patients With Peripheral Arterial Disease

Background: Characteristics of gait in peripheral arterial disease (PAD) patients are short step length and slow walking speed. It was reported that reduced walking speed was associated with increasing mortality in PAD patients. However, the detail of gait in PAD patients has not been fully clarified. We hypothesized that PAD patients show abnormal gait pattern, in particular in late stance phase (propulsion phase), at comfortable and fast walking speed. Methods: Sixteen symptomatic PAD patients (71±9 years old), who were 11 bilateral and 5 unilateral intermittent claudication (27 claudication limbs), and 7 healthy controls (14 healthy limbs) were recruited. With a 3-dimensional motion analysis system, peak hip joint generated power (HJP: pull-off power) and ankle joint generated power (AJP: push-off power) in late stance were analyzed at comfortable and fast walking speed. Ankle/hip (A/P) peak power ratio was calculated to determine whether hip or ankle power was dominantly used in late stance during walking. Results: Mean ankle-brachial index was 0.63±0.20 in claudication limbs. Pain lesions were buttock, thigh and calf in 8, 3 and 16 limbs, respectively. Compared with healthy controls, the PAD patients showed significant slower walking speed and shorter step length at comfortable and fast walking speed (p&lt; 0.001). The peak HJP and AJP in late stance were significantly lower in the PAD patients at both walking speed. However, when gait speed adjusted, only peak HJP in late stance was significantly lower in the PAD patients at comfortable walking speed (p=0.025). The A/P peak power ratio was higher in the PAD patients at comfortable and fast walking speed (p=0.020, p=0.045, respectively). Among the PAD patients, the HJP, AJP and A/P peak power ratio were not significantly different between buttock pain and calf pain. Conclusions: PAD patients used relatively ankle planter flexors to compensate a muscle weakness of hip flexor at comfortable and fast walking speed. These results suggest that exercise training for hip flexor muscle may increase walking distance and mitigate calf pain during walking in PAD patients.

Mechanical and energetic consequences of reduced ankle plantar-flexion in human walking.

The human ankle produces a large burst of 'push-off' mechanical power late in the stance phase of walking, reduction of which leads to considerably poorer energy economy. It is, however, uncertain whether the energetic penalty results from poorer efficiency when the other leg joints substitute for the ankle's push-off work, or from a higher overall demand for work due to some fundamental feature of push-off. Here, we show that greater metabolic energy expenditure is indeed explained by a greater demand for work. This is predicted by a simple model of walking on pendulum-like legs, because proper push-off reduces collision losses from the leading leg. We tested this by experimentally restricting ankle push-off bilaterally in healthy adults (N=8) walking on a treadmill at 1.4 m s(-1), using ankle-foot orthoses with steel cables limiting motion. These produced up to ∼50% reduction in ankle push-off power and work, resulting in up to ∼50% greater net metabolic power expenditure to walk at the same speed. For each 1 J reduction in ankle work, we observed 0.6 J more dissipative collision work by the other leg, 1.3 J more positive work from the leg joints overall, and 3.94 J more metabolic energy expended. Loss of ankle push-off required more positive work elsewhere to maintain walking speed; this additional work was performed by the knee, apparently at reasonably high efficiency. Ankle push-off may contribute to walking economy by reducing dissipative collision losses and thus overall work demand.