The effects of prosthetic ankle dorsiflexion and energy return on below-knee amputee leg loading

Background

Prosthetic devices are intended to return lower limb amputees to their pre-amputation functional status. However, prosthetic devices designed for unilateral below-knee amputees have yet to completely restore the biomechanical functions normally provided by the ankle muscles, leading to gait asymmetries and increased reliance on their intact leg. In an effort to improve amputee gait, energy storage and return feet have been developed that store mechanical energy in elastic structures in early to mid-stance and return it in late stance. However, little is known regarding how ankle compliance and the level of energy return influences walking mechanics. The purpose of this study was to identify the influence of prosthetic ankle dorsiflexion and energy storage and return on leg loading during steady-state walking.

Methods

Compliant ankles with different stiffness levels were attached to a Seattle Lightfoot2 in different orientations (forward- and reverse-facing).

Findings

The ankles decreased residual leg vertical ground reaction forces in late stance, increased residual leg propulsive ground reaction force impulses and increased residual leg knee joint extensor moments. The reverse-facing ankles increased residual leg vertical ground reaction forces in early stance, and the compliant forward-facing ankle increased residual leg braking impulses. In contrast to previous studies, increased energy storage and return from compliant ankles did not decrease hip joint powers or the intact leg vertical ground reaction forces.

Interpretation

These results provide insight into the relationships between ankle dorsiflexion, energy storage and return, and leg loading, which may lead to more effective prosthetic devices to improve amputee gait.     

Attenuation of centre-of-pressure trajectory fluctuations under the prosthetic foot when using an articulating hydraulic ankle attachment compared to fixed attachment

Background

Disruptions to the progress of the centre-of-pressure trajectory beneath prosthetic feet have been reported previously. These disruptions reflect how body weight is transferred over the prosthetic limb and are governed by the compliance of the prosthetic foot device and its ability to simulate ankle function. This study investigated whether using an articulating hydraulic ankle attachment attenuates centre-of-pressure trajectory fluctuations under the prosthetic foot compared to a fixed attachment.

Methods

Twenty active unilateral trans-tibial amputees completed walking trials at their freely-selected, comfortable walking speed using both their habitual foot with either a rigid or elastic articulating attachment and a foot with a hydraulic ankle attachment. Centre-of-pressure displacement and velocity fluctuations beneath the prosthetic foot, prosthetic shank angular velocity during stance, and walking speed were compared between foot conditions.

Findings

Use of the hydraulic device eliminated or reduced the magnitude of posteriorly directed centre-of-pressure displacements, reduced centre-of-pressure velocity variability across single-support, increased mean forward angular velocity of the shank during early stance, and increased freely chosen comfortable walking speed (P ≤ 0.002).

Interpretation

The attenuation of centre-of-pressure trajectory fluctuations when using the hydraulic device indicated bodyweight was transferred onto the prosthetic limb in a smoother, less faltering manner which allowed the centre of mass to translate more quickly over the foot.     

Comparison of the International Committee of the Red Cross Foot With the Solid Ankle Cushion Heel Foot During Gait: A Randomized Double-Blind Study

Objective

To compare the well-recognized solid ankle cushion heel (SACH) foot with the prosthetic foot developed by the International Committee of the Red Cross (CR Equipements SACH) during gait.

Design

Double-blind study was conducted to compare the influence on the biomechanics of gait of the CR Equipements SACH foot and the SACH foot.

Setting

University hospital research center.

Participants

Participants with unilateral transtibial amputation (N=15) were included.

Interventions

Three-dimensional motion analysis system and 2 forceplates were used to capture body motion and ground reaction forces during gait at a self-selected speed and at 1.2m/s.

Main Outcome Measures

Nonparametric Wilcoxon matched-pairs tests were used to compare the 2 prosthetic feet with respect to their spatiotemporal (gait velocity, stride length, and percentage of stance phase), kinematic (range and peak angles of the pelvis, hip, knee, and ankle), and kinetic (peak moment and power of the hip, knee, and ankle) parameters.

Results

Compared with the SACH foot, the CR Equipements SACH foot demonstrated a significantly greater stance phase symmetry ratio (SACH: 94% vs CR Equipements SACH: 97%), a more extensive ankle range of motion in the sagittal plane (SACH: 7° vs CR Equipements SACH: 12°), a greater maximal dorsiflexion angle during the terminal stance phase (SACH: 10° vs CR Equipements SACH: 13°), and a higher ankle power (SACH: .31W/kg vs CR Equipements SACH: .40W/kg). No significant difference was found for the examined knee, hip, and pelvis parameters.

Conclusions

The CR Equipements SACH foot provides more symmetry and improves ankle kinematics and kinetics in the sagittal plane compared with the SACH foot. This study suggests that individuals using the CR Equipements SACH foot improve their gait biomechanics compared when using the SACH foot.     

Effects of a knee–ankle–foot orthosis on gait biomechanical characteristics of paretic and non-paretic limbs in hemiplegic patients with genu recurvatum

Background

A knee–ankle–foot orthosis may be prescribed for the prevention of genu recurvatum during the stance phase of gait. It allows also to limit abnormal plantarflexion during swing phase. The aim is to improve gait in hemiplegic patients and to prevent articular degeneration of the knee. However, the effects of knee–ankle–foot orthosis on both the paretic and non-paretic limbs during gait have not been evaluated. The aim of this study was to quantify biomechanical adaptations induced by wearing a knee–ankle–foot orthosis, on the paretic and non-paretic limbs of hemiplegic patients during gait.

Methods

Eleven hemiplegic patients with genu recurvatum performed two gait analyses (without and with the knee–ankle–foot orthosis). Spatio-temporal, kinematic and kinetic gait parameters of both lower limbs were quantified using an instrumented gait analysis system during the stance and swing phases of the gait cycle.

Findings

The knee–ankle–foot orthosis improved spatio-temporal gait parameters. During stance phase on the paretic side, knee hyperextension was reduced and ankle plantarflexion and hip flexion were increased. During swing phase, ankle dorsiflexion increased in the paretic limb and knee extension increased in the non-paretic limb. The paretic limb knee flexion moment also decreased.

Interpretation

Wearing a knee–ankle–foot orthosis improved gait parameters in hemiplegic patients with genu recurvatum. It increased gait velocity, by improving cadence, stride length and non-paretic step length. These spatiotemporal adaptations seem mainly due to the decrease in knee hyperextension during stance phase and to the increase in paretic limb ankle dorsiflexion during both phases of the gait cycle.     

A pilot study to investigate the combined use of Botulinum toxin type-a and ankle foot orthosis for the treatment of spastic foot in chronic hemiplegic patients

Background

Botulinum toxin is commonly used to treat spastic equinus foot. This treatment seems to improve gait in hemiplegic patients when used alone or combined with an ankle-foot orthosis. However, the nature and effects of this improvement have until now rarely been studied. The aim of this study was to quantify the impact of a Botulinum toxin injection in the triceps surae of hemiplegic patients with equinus foot, used either alone or in combination with an ankle-foot orthosis, on the kinematics and dynamics of the paretic lower limb, and to determine the advantage of combining an ankle-foot orthosis with this pharmacological treatment.

Methods

Patients were assessed using gait analysis to measure spatio-temporal, kinematic and dynamic parameters of the gait cycle before Botulinum toxin injection and then 3 and 6 weeks after injection. Eight chronic hemiplegics following central nervous system lesion were included.

Findings

Botulinum toxin injection led to an increase in velocity, peak ankle dorsiflexion during stance phase, and peak knee flexion during swing phase. It also resulted in an increased peak plantarflexion moment. Use of ankle-foot orthosis led to a specific increase in peak ankle dorsiflexion during swing phase and also increased peak plantarflexion moment.

Interpretation

The results indicate that combined Botulinum toxin injection of the triceps surae and wearing an ankle-foot orthosis is more effective than the use of Botulinum toxin only. Use of an ankle-foot orthosis increases ankle dorsiflexion during the swing phase and does not reduce the benefits gained by the use of Botulinum toxin in stance phase.     

Frontal plane compensatory strategies associated with self-selected walking speed in individuals post-stroke

Background

Approximately two out of three individuals post-stroke experience walking impairments. Frontal plane compensatory strategies (i.e. pelvic hiking and circumduction) are observed in post-stroke gait in part to achieve foot clearance in response to reduced knee flexion and ankle dorsiflexion. The objective of this study was to investigate the relationship between self-selected walking speed and the kinematic patterns related to paretic foot clearance during post-stroke walking.

Methods

Gait analysis was performed at self-selected walking speed for 21 individuals post-stroke. Four kinematic variables were calculated during the swing phase of the paretic limb: peak pelvic tilt (pelvic hiking), peak hip abduction (circumduction), peak knee flexion, and peak ankle dorsiflexion. Paretic joint angles were analyzed across self-selected walking speed as well as between functionally relevant ambulation categories (Household < 0.4 m/s, Limited Community 0.4–0.8 m/s, Community > 0.8 m/s).

Findings

While all subjects exhibited similar foot clearance, slower walkers exhibited greater peak pelvic hiking and less knee flexion, ankle dorsiflexion, and circumduction compared to faster walkers (P < .05). Additionally, four of the fastest walkers compensated for poor knee flexion and ankle dorsiflexion through large amounts of circumduction.

Interpretation

These findings suggest that improved gait performance after stroke, as measured by self-selected walking speed, is not necessarily always accomplished through gait patterns that more closely resemble healthy gait for all variables. It appears the ability to walk fast is achieved by either sufficient ankle dorsiflexion and knee flexion to achieve foot clearance or the employment of circumduction to overcome a deficit in either ankle dorsiflexion or knee flexion.     

Contribution of knee adduction moment impulse to pain and disability in Japanese women with medial knee osteoarthritis

Background

An increase in the knee adduction moment is one of the risk factors of medial knee osteoarthritis. This study examined the relationship between knee adduction moment and self-reported pain and disability. We also investigated the influence of pain on the relationships between knee adduction moment and gait performance and disability.

Methods

Thirty-eight Japanese women with medial knee osteoarthritis participated in this study (66.37 years (41–79 years)). Gait analysis involved the measurement of the external knee adduction moment impulse in the stance duration and during 3 subdivisions of stance. The total, pain and stiffness, and physical function Japanese Knee Osteoarthritis Measure scores were determined.

Findings

The pain and stiffness, physical function, and total scores were positively correlated with the knee adduction moment impulses in the stance duration, and initial and second double support interval, and single limb support interval. The knee adduction moment impulse during the stance duration was related to the pain and stiffness subscale and gait velocity. The pain and stiffness subscale was related to the physical function subscale.

Interpretation

Our results suggest that increasing in the knee adduction moment impulse, a proxy for loading on the medial compartment of the knee, is related to increased pain during weight-bearing activities such as walking, thereby restricting walking performance and causing disability by reducing gait velocity. Thus, the reduction in the knee adduction moment impulse during gait may result in pain relief and may serve as a conservative treatment option with disease-modifying potential.     

The influence of energy storage and return foot stiffness on walking mechanics and muscle activity in below-knee amputees

Background

Below-knee amputees commonly experience asymmetrical gait patterns and develop comorbidities in their intact and residual legs. Carbon fiber prosthetic feet have been developed to minimize these asymmetries by utilizing elastic energy storage and return to provide body support, forward propulsion and leg swing initiation. However, how prosthetic foot stiffness influences walking characteristics is not well-understood. The purpose of this study was to identify the influence of foot stiffness on kinematics, kinetics, muscle activity, prosthetic energy storage and return, and mechanical efficiency during amputee walking.

Methods

A comprehensive biomechanical analysis was performed on 12 unilateral below-knee amputees. Subjects walked overground at 1.2 m/s with three prosthetic feet of varying keel and heel stiffness levels, which were created using additive manufacturing.

Findings

As stiffness decreased, peak residual and intact leg ankle angles and residual leg knee flexion angle increased. The residual and intact leg braking ground reaction forces and knee extensor moments, residual leg vastus and gluteus medius activity, and intact leg vastus and rectus femoris activity also increased. The second vertical ground reaction force peak and hamstring activity in the residual leg and first vertical ground reaction force peak in the intact leg decreased. In addition, prosthetic energy storage and return increased and mechanical efficiency decreased as stiffness decreased.

Interpretation

Decreasing foot stiffness can increase prosthesis range of motion, mid-stance energy storage and late-stance energy return, but the net contributions to forward propulsion and swing initiation may be limited as additional muscle activity to provide body support becomes necessary.     

Impact on the biomechanics of overground gait of using an ‘Echelon’ hydraulic ankle–foot device in unilateral trans-tibial and trans-femoral amputees

Background

If a prosthetic foot creates resistance to forwards shank rotation as it deforms during loading, it will exert a braking effect on centre of mass progression. The present study determines whether the centre of mass braking effect exerted by an amputee's habitual rigid ‘ankle’ foot was reduced when they switched to using an ‘Echelon’ hydraulic ankle–foot device.

Methods

Nineteen lower limb amputees (eight trans-femoral, eleven trans-tibial) walked overground using their habitual dynamic-response foot with rigid ‘ankle’ or ‘Echelon’ hydraulic ankle–foot device. Analysis determined changes in how the centre of mass was transferred onto and above the prosthetic-foot, freely chosen walking speed, and spatio-temporal parameters of gait.

Findings

When using the hydraulic device both groups had a smoother/more rapid progression of the centre of pressure beneath the prosthetic hindfoot (p ≤ 0.001), and a smaller reduction in centre of mass velocity during prosthetic-stance (p < 0.001). As a result freely chosen walking speed was higher in both groups when using the device (p ≤ 0.005). In both groups stance and swing times and cadence were unaffected by foot condition whereas step length tended (p < 0.07) to increase bilaterally when using the hydraulic device. Effect size differences between foot types were comparable across groups.

Interpretation

Use of a hydraulic ankle–foot device reduced the foot's braking effect for both amputee groups. Findings suggest that attenuation of the braking effect from the foot in early stance may be more important to prosthetic-foot function than its ability to return energy in late stance.     

Biomechanics of walking with silicone prosthesis after midtarsal (Chopart) disarticulation

Background

Currently accepted understanding is that silicone foot prostheses have little influence on biomechanics of walking; however clinical observations suggest several beneficial effects. The objective of this study was to characterize biomechanics of gait in a group of subjects with disarticulation through the talonavicular (T-N) and calcaneocuboid (C-C) (midtarsal) joints wearing two different prosthetic solutions: silicone prostheses and conventional prostheses.

Methods

Four subjects that underwent Chopart partial foot amputation were included in the study. Silicone prosthesis was custom manufactured for each individual subject. Instrumented gait analysis was performed in each subject in four experimental conditions: barefooted, barefooted and wearing silicon prosthesis, wearing footwear with conventional prosthesis and wearing footwear with silicon prosthesis. Comparisons and statistical analysis were made between both barefooted conditions and both foot-wearing conditions.

Findings

Our results show that silicone prosthesis without reinforced sole increases gait velocity, improves generation of ankle plantarflexion moment throughout the stance phase and enables greater power generation at push-off. The most important changes, however, occur in the frontal plane, where improved hip adduction angles and higher hip abduction moment in the stance enable more normal pelvic movement and consequently also less trunk inclination toward amputated side.

Interpretation

We conclude that silicone prostheses are not solely for cosmetic reasons but may be also biomechanically superior over other prosthetic solutions, especially for walking barefoot.     

The effect of isolated gastrocnemius contracture and gastrocnemius recession on lower extremity kinematics and kinetics during stance

Background

Isolated gastrocnemius contracture limits ankle dorsiflexion with full knee extension and is potentially problematic during mid-stance of gait when 10° of dorsiflexion and full knee extension are needed. It is during this time that patients with isolated gastrocnemius contracture may demonstrate altered kinematics and/or kinetics. When conservative management fails to resolve painful foot pathologies associated with non-spastic isolated gastrocnemius contracture, gastrocnemius recession surgery has been suggested to resolve contracture and improve function and strength. However, there are no published reports on lower extremity kinematics/kinetics in the non-spastic isolated gastrocnemius contracture population. Assessment of alterations in gait mechanics is necessary to examine the effects of this potential surgical intervention.

Methods

Lower extremity kinematics and kinetics were assessed in 6 patients clinically diagnosed with isolated gastrocnemius contracture pre- and post-surgical recession compared with 33 healthy control participants.

Findings

Pre-operatively, patients with isolated gastrocnemius contracture demonstrated significantly increased peak knee flexion angles and knee flexion moments during mid-stance. There were no differences in peak ankle dorsiflexion angle or peak plantar flexion moment. Gastrocnemius recession did not alter gait kinematics/kinetics following surgery. Joint kinematic strategies utilized to compensate for isolated gastrocnemius contracture varied minimally between participants with IGC; most employed a flexed knee strategy, while one participant utilized a reduced ankle dorsiflexion strategy.

Interpretation

Select post-surgical gait mechanics were unaltered; however, gait mechanics were not similar between non-spastic isolated gastrocnemius contracture patients and healthy control participants. Surgical intervention for patients with isolated gastrocnemius contracture does not appear to create any negative gait adaptations; however, patients may benefit from gait retraining post-recession as maladaptive gait patterns persist post operatively.     

The effect of ankle foot orthosis stiffness on the energy cost of walking: a simulation study

Background

In stroke and multiple sclerosis patients, gait is frequently hampered by a reduced ability to push-off with the ankle caused by weakness of the plantar-flexor muscles. To enhance ankle push-off and to decrease the high energy cost of walking, spring-like carbon-composite Ankle Foot Orthoses are frequently prescribed. However, it is unknown what Ankle Foot Orthoses stiffness should be used to obtain the most efficient gait. The aim of this simulation study was to gain insights into the effect of variation in Ankle Foot Orthosis stiffness on the amount of energy stored in the Ankle Foot Orthosis and the energy cost of walking.

Methods

We developed a two-dimensional forward-dynamic walking model with a passive spring at the ankle representing the Ankle Foot Orthosis and two constant torques at the hip for propulsion. We varied Ankle Foot Orthosis stiffness while keeping speed and step length constant.

Findings

We found an optimal stiffness, at which the energy delivered at the hip joint was minimal. Energy cost decreased with increasing energy storage in the ankle foot orthosis, but the most efficient gait did not occur with maximal energy storage. With maximum storage, push-off occurred too late to reduce the impact of the contralateral leg with the floor. Maximum return prior to foot strike was also suboptimal, as push-off occurred too early and its effects were subsequently counteracted by gravity. The optimal Ankle Foot Orthosis stiffness resulted in significant push-off timed just prior to foot strike and led to greater ankle plantar-flexion velocity just before contralateral foot strike.

Interpretation

Our results suggest that patient energy cost might be reduced by the proper choice of Ankle Foot Orthosis stiffness.     

Gait adaptation in chronic anterior cruciate ligament-deficient patients: Pivot-shift avoidance gait

Background

A variety of biomechanical adaptations of the knee during gait have been reported in ACL-deficient patients to cope with anteroposterior knee instability. However, strategies to prevent rotatory knee instability are less recognized. We hypothesized that ACL-deficient patients would make distinctive gait changes to prevent anterolateral rotatory knee instability. Specifically, we hypothesized that during the terminal stance phase of the gait cycle, ACL-deficient patients would reduce the internal rotation knee joint moment and exhibit a higher knee flexion angle. We call this altered gait a pivot-shift avoidance gait. We also hypothesized that patients would not be able to adapt their knee biomechanics as efficiently at a fast gait speed.

Methods

Twenty-nine patients with chronic ACL deficiency and 15 healthy volunteers took part in a treadmill gait analysis. The terminal stance phase was analyzed under both comfortable and fast gait speed conditions.

Findings

At both gait speeds, ACL-deficient patients significantly reduced the internal rotation knee joint moment and showed larger knee flexion angles during the terminal stance phase of the gait cycle than did the control group. However, the difference in the minimum knee flexion angle between groups under the fast gait speed condition was not statistically significant.

Interpretation

ACL-deficient patients adopted the proposed pivot-shift avoidance gait, possibly to prevent anterolateral rotatory knee instability. The patients were not able to adapt their knee biomechanics as effectively during fast-paced walking. This study reinforces the pertinence of gait analysis in ACL-deficient knees to acquire more information about the function of the knee joint.     

Sagittal plane position of the functional joint centre of prosthetic foot/ankle mechanisms

Background

The use of motion analysis techniques in amputee rehabilitation often utilizes kinematic data from the prosthetic limb. A problem with methods currently used is that the joint positions of the prosthetic ankle are assumed to be in the same position as that of an intact ankle. The aim of this study was to identify both traditional anatomical joint centres as well as functional joint centres in a selection of commonly used prosthetic feet. These coordinates were then compared across feet and compared to the contralateral intact ankle joint.

Methods

Six prosthetic feet were fit to a unilateral trans-tibial amputee on two separate occasions. The subject's intact limb was used as a control. Three-dimensional kinematics were collected to determine the sagittal position of the functional joint centre for the feet investigated.

Findings

None of the prosthetic feet had a functional joint centre that was within the 95% CI for that of an intact ankle (both x- and y-coordinate position), nor any of the other prosthetic feet investigated. The repeatability of the method was found to be adequate, with 95% CI of the difference (test–retest) of the prosthetic feet similar to that for the intact ankle and within clinically accepted levels of variability.

Interpretation

The motion of the prosthetic feet tested is clearly different from that of an intact ankle. Kinematic methods that assume ankle constraints based on an intact ankle are subject to systematic error as this does not reflect the real motion of the prosthetic foot.     

Biomechanical mechanisms of toe-out gait performance in people with and without knee osteoarthritis

Background

Toe-out gait modification (increased toe-out angle) has been proposed to decrease medial knee joint loading and slow disease progression in patients with knee osteoarthritis. However, the manner in which toe-out gait modification is performed is unknown. The purposes of this study were to assess the biomechanical strategies of achieving a toe-out gait, and to compare these strategies between older individuals with knee osteoarthritis and young, healthy individuals.

Methods

Lower limb biomechanics were evaluated for ten patients with knee osteoarthritis and for ten young, healthy individuals during treadmill walking. Two trials, consisting of natural gait followed by a ten degree increase in toe-out angle were performed. Transverse plane rotations of the thigh, shank and foot segments were calculated and compared between walking conditions and groups.

Findings

External rotation changes with toe-out were significantly different between the thigh and shank, and thigh and foot (P < 0.001), but not between the shank and foot (P = 0.48). External rotation at each segment was not significantly different (P > 0.05) between groups, with the exception of thigh rotation during natural gait (P = 0.04).

Interpretation

Current findings suggest that increased toe-out gait is primarily achieved through rotation of the shank and foot, with less contribution from the thigh, and those individuals with knee osteoarthritis perform a toe-out gait biomechanically similar to young, healthy individuals. Gait modification programs should address individuals' limitations, such as joint stiffness, to ensure functional performance of toe-out gait modification.     

Effects of walking with loads above the ankle on gait parameters of persons with hemiparesis after stroke

Background

Walking with a load at the ankle during gait training is a simple way to resist lower limb movements to induce functional muscle strengthening. This study investigated the effects of walking with different loads attached above the paretic ankle on biomechanical gait parameters during over ground walking in post-stroke participants.

Methods

Ten participants with moderate chronic hemiparesis were evaluated while walking over ground with three different loads (0.5, 1.0, and 1.5 kg) attached above the paretic ankle. Gait speed, cadence, step lengths as well as hip and knee angular displacements, joint moments and power of the paretic limb were compared while walking with and without loads.

Findings

Walking with a load led to an increased in gait speed (+ 0.03–0.05 m/s), and in step length of the paretic leg (+ 5.6 to 9.4% step length, effect size = 0.49–0.63), but not of the non-paretic leg. The proportion of the stance and swing phases did not change. Maximal joint moments (+ 20 to 48%, effect size = 0.26–0.55) and power (+ 20 to 114%, effect size = 0.30–0.57) increases varied across participants but were mostly affected in early stance at the hip and during the late swing phase at the knee. Mean angular displacement changes were less than 4°.

Interpretation

Post-stroke participants are able to increase hip and knee power bursts to meet the increased mechanical demand of added loads attached to the paretic ankle, while preserving the basic pattern of walking. Further study is needed before using loading to functionally strengthen paretic muscles.     

The impact of simulated ankle plantarflexion contracture on the knee joint during stance phase of gait: A within-subject study

Background

Ankle plantarflexion contractures are common in adults with neurological disorders and known to cause secondary gait deviations. However, their impact on the knee joint is not fully understood. The aims of this study are to describe the effect of simulated plantarflexion contractures on knee biomechanics during the stance phase and on the spatiotemporal characteristics of gait.

Methods

Mild (10–degree plantarflexion) and severe (20–degree plantarflexion) ankle contractures were simulated in thirteen able-bodied adults using an ankle-foot-orthosis. A no contracture condition was compared with two simulated contracture conditions.

Findings

There was an increase in knee extension, sometimes resulting in hyperextension, throughout stance for the two contracture conditions compared to the no contracture condition (mean increase in knee extension ranged from 5° to 9°; 95% CI 0° to 17°). At the same time, there were reductions in extension moment and power generation at the knee. Simulated plantarflexion contractures also reduced gait velocity, bilateral step length and cadence. All these changes were more pronounced in the severe contracture condition than mild contracture condition. While the majority of participants adopted a foot-flat pattern on landing and exhibited an increase in knee extension during stance, two participants used a toe-walking pattern and exhibited an increase in knee flexion.

Interpretation

Ankle plantarflexion contractures are associated with an increase in knee extension during stance phase. However, some people with simulated ankle contractures may walk with an increase in knee flexion instead. Ankle plantarflexion contractures also adversely affect gait velocity, step length and cadence.     

Home-Based Treadmill Training to Improve Gait Performance in Persons With a Chronic Transfemoral Amputation

Objective

To investigate the effectiveness of a home-based multiple-speed treadmill training program to improve gait performance in persons with a transfemoral amputation (TFA).

Design

Repeated measures.

Setting

Research laboratory.

Participants

Individuals with a TFA (N=8) who had undergone a unilateral amputation at least 3 years prior as a result of limb trauma or cancer.

Intervention

Home-based treadmill walking for a total of 30 minutes a day, 3 days per week for 8 weeks. Each 30-minute training session involved 5 cycles of walking for 2 minutes at 3 speeds.

Main Outcome Measures

Participants were tested pretraining and after 4 and 8 weeks of training. The primary measures were temporal-spatial gait performance (symmetry ratios for stance phase duration and step length), physiological gait performance (energy expenditure and energy cost), and functional gait performance (self-selected walking speed [SSWS], maximum walking speed [MWS], and 2-minute walk test [2MWT]).

Results

Eight weeks of home-based training improved temporal-spatial gait symmetry at SSWS but not at MWS. A relative interlimb increase in stance duration for the prosthetic limb and proportionally greater increases in step length for the limb taking shorter steps produced the improved symmetry. The training effect was significant for the step length symmetry ratio within the first 4 weeks of the program. Energy expenditure decreased progressively during the training with nearly 10% improvement observed across the range of walking speeds. SSWS, MWS, and 2MWT all increased by 16% to 20%.

Conclusions

Home-based treadmill walking is an effective method to improve gait performance in persons with TFA. The results support the application of training interventions beyond the initial rehabilitation phase, even in individuals considered highly functional.     

Role of ankle mobility in foot rollover during gait in individuals with diabetic neuropathy

Background

The purpose of this study was to investigate the ankle range of motion during neuropathic gait and its influence on plantar pressure distribution in two phases during stance: at heel–strike and at push-off.

Methods

Thirty-one adults participated in this study (control group, n = 16; diabetic neuropathic group, n = 15). Dynamic ankle range of motion (electrogoniometer) and plantar pressures (PEDAR-X system) were acquired synchronously during walking. Plantar pressures were evaluated at rearfoot, midfoot and forefoot during the two phases of stance. General linear model repeated measures analysis of variance was applied to investigate relationships between groups, areas and stance phases.

Findings

Diabetic neuropathy patients walked using a smaller ankle range of motion in stance phase and smaller ankle flexion at heel–strike (P = 0.0005). Peak pressure and pressure–time integral values were higher in the diabetic group in the midfoot at push-off phase when compared to heel–strike phase. On the other hand, the control group showed similar values of peak pressure in midfoot during both stance phases.

Interpretation

The ankle mobility reduction observed could be associated to altered plantar pressure distribution observed in neuropathic subjects. Results demonstrated that midfoot and forefoot play a different role in subjects with neuropathy by receiving higher loads at push-off phase that are probably due to smaller ankle flexion at stance phase. This may explain the higher loads in anterior areas of the foot observed in diabetic neuropathy subjects and confirm an inadequate foot rollover associated to the smaller ankle range of motion at the heel–strike phase.     

Gastrocnemius tightness on joint angle and work of lower extremity during gait

Background

Muscular tightness is a common clinical musculoskeletal disorder and is regarded as a predisposing factor for muscle injuries. In this study, a two-way mixed design ANOVA was applied to investigate the effects of the gastrocnemius tightness on the joint angle and joint work during walking.

Methods

Twenty-two patients with muscular tightness of gastrocnemius muscle (<12° of ankle dorsiflexion with knee extended) and 22 age- and gender-matched subjects with normal gastrocnemius flexibility (>15° of ankle dorsiflexion with knee extended) participated in this study. The joint angle and work at hip, knee, and ankle joints during the stance phase were analyzed at two preset cadences of 100 steps/min and 140 steps/min.

Findings

Significantly greater flexion angles at hip (P = 0.025) and knee (P = 0.001) were found in the tightness group at the time of maximal ankle dorsiflexion. Significantly less work generation at knee (P = 0.034) and greater work absorption at ankle (P = 0.024) were detected in the tightness group.

Interpretation

The subjects with gastrocnemius tightness revealed a compensatory gait pattern, which included the changes in the joint angles and associated work productions. The potential disturbance of the knee control and strain injuries of plantar flexors might be crucial in the clinical considerations for subjects with gastrocnemius tightness.