Effect of flexion-resist and extension-assist knee orthosis on electromyographic activities of quadriceps during lateral stepping.

Knee orthoses can potentially reduce muscular activities of the quadriceps. The aim of this study was to investigate the effect of a custom flexion-resist and extension-assist knee orthosis on electromyographic activities of quadriceps during lateral stepping (step-up and step-down). Flexion resistance and extension assistance mechanisms were set by a pair of linear springs built into the orthotic knee joints. Electromyography (EMG) signals were collected from rectus femoris (RF), vastus medialis obliquus (VMO), and vastus lateralis (VL) during lateral step-up and lateral step-down activities in 7 healthy young adults. Peak normalized root mean square (RMS) EMG signals of each muscle, as well as VMO:VL ratio, were compared between orthotic and nonorthotic conditions using the Wilcoxon signed-rank test. The knee orthosis significantly reduced the normalized RMS EMG signals of the RF and VL during lateral stepping ( p < 0.05). No significant difference was found in the VMO. The VMO:VL ratio significantly ( p < 0.05) increased under orthotic condition. The experiments demonstrated that the knee orthosis reduces the peak normalized RMS EMG signals of RF and VL, and alter the VMO:VL ratio of quadriceps in healthy young adults. Therefore, this study suggests that the flexion-resist and extension-assist knee orthosis may be effective in reducing muscular activities of RF and VL, which may alleviate patellofemoral loading. Future studies should delve into the effects of the knee orthosis in individuals with patellofemoral pain.

Effectiveness of Insole Colour on Impact Loading and Lower-Limb Kinematics When Running at Preferred and Nonpreferred Speeds.

While colour of red can play a significant role in altering human perception and performances, little is known about its perceptual-motor effect on running mechanics. This study examined the effects of variations in insole colours on impact forces, ankle kinematics, and trial-to-trial reliability at various running speeds. Sixteen male recreational runners ran on instrumented treadmill at slow (90%), preferred (100%), and fast (110%) running speeds when wearing insoles in red, blue, and white colours. We used synchronized force platform and motion capturing system to measure ground reaction force, ankle sagittal and frontal kinematics, and movement variability. A two-way (colour x speed) ANOVA with repeated measures was performed with Bonferroni adjusted post hoc comparisons, with alpha set at 0.05. Data analyses indicated that participants demonstrated higher impact and maximum loading rate of ground reaction force, longer stride length, shorter contact time, and smaller touchdown ankle inversion as well as larger ankle sagittal range of motion (RoM), but smaller frontal RoM in fast speed as compared with preferred (P < 0.05) and slow speeds (P < 0.001). Although insole colour had minimal effect on mean values of any tested variables (P > 0.05), participants wearing red-coloured orthoses showed higher coefficient of variation values for maximum loading rate than wearing blue insoles (P=0.009). These results suggest that running at faster speed would lead to higher impact loading and altered lower-limb mechanics and that colour used on the tops of insoles influences the wearers' movement repeatability, with implications for use of foot insole in running.

Effectiveness and Reliability of Foot Orthoses on Impact Loading and Lower Limb Kinematics When Running at Preferred and Nonpreferred Speeds.

This study examined the effect of foot orthoses used on ground reaction forces, ankle, and knee kinematics when running at preferred and nonpreferred speeds. Sixteen runners ran on instrumented treadmills at various speeds (90%, 100%, and 110% of preferred speed) when wearing arch-support and flat-control orthoses. Two-way repeated analysis of variance (ANOVA) was performed on the mean and coefficient of variation of all variables. Results indicated that arch-support orthoses experienced larger maximum loading rates than flat-control orthoses (P = .017, 95% CI, 2.22 to 19.53). Slower speed was related to smaller loading rates (preferred: P = .002, 95% CI, -17.02 to -4.20; faster: P = .003, 95% CI, -29.78 to -6.17), shorter stride length (preferred: P < .001, 95% CI, -0.204 to -0.090; faster: P < .001, 95% CI, -0.382 to -0.237), and longer contact time (preferred: P < .001, 95% CI, 0.006-0.021; faster: 95% CI, 0.012-0.042). In arch-support condition, preferred speed induced higher stride length coefficient of variation (P = .046, 95% CI, 0.035-1.117) than faster speed, while displaying no differences in flat-control condition. These findings suggest that the use of arch-support orthoses would influence impact loading, but not spatial-temporal and joint kinematics in recreational runners.

Shape Memory Ankle-Foot Orthoses.

Electrically actuated ankle-foot orthoses (AFOs) were designed and prototyped using shape memory textile composites. Acrylic copolymers were synthesized as the matrix to demonstrate shape memory effects, whereas electrothermal fabrics were embedded to generate uniform heat as a trigger. Superior to conventional polymeric orthoses, shape memory AFOs (SM-AFOs) could be repeatedly programmed at least 20 times with stable shape fixity and recovery. Evidenced by clinical practice, SM-AFOs were effectively actuated at 10 V, allowing the correction of ankle angles with 10° plantarflexion. Ultimately, we envision a smart orthopedic system that can advance progressive rehabilitation with manipulation under safe and convenient conditions.

Temperature measurement and control system for transtibial prostheses: Functional evaluation.

The accumulation of heat inside the prosthetic socket increases skin temperature and fosters perspiration, which consequently leads to high tissue stress, friction blister, discomfort, unpleasant odor, and decreased prosthesis suspension and use. In the present study, the prototype of a temperature measurement and control (TM&C) system was designed, fabricated, and functionally evaluated in a phantom model of the transtibial prosthetic socket. The TM&C system was comprised of 12 thermistors divided equally into two groups that arranged internal and external to a prosthetic silicone liner. Its control system was programmed to select the required heating or cooling function of a thermal pump to provide thermal equilibrium based on the amount of temperature difference from a defined set temperature, or the amount of difference between the mean temperature recorded by inside and outside thermistors. A thin layer of aluminum was used for thermal conduction between the thermal pump and different sites around the silicone liner. The results showed functionality of the TM&C system for thermoregulation inside the prosthetic socket. However, enhancing the structure of this TM&C system, increasing its thermal power, and decreasing its weight and cost are main priorities before further development.

Temperature measurement and control system for transtibial prostheses: Single subject clinical evaluation.

The snug fit of a prosthetic socket over the residual limb can disturb thermal balance and put skin integrity in jeopardy by providing an unpleasant and infectious environment. The prototype of a temperature measurement and control (TM&C) system was previously introduced to resolve thermal problems related to prostheses. This study evaluates its clinical application in a setting with reversal, single subject design. The TM&C system was installed on a fabricated prosthetic socket of a man with unilateral transtibial amputation. Skin temperature of the residual limb without prosthesis at baseline and with prosthesis during rest and walking was evaluated. The thermal sense and thermal comfort of the participant were also evaluated. The results showed different skin temperature around the residual limb with a temperature decrease tendency from proximal to distal. The TM&C system decreased skin temperature rise after prosthesis wearing. The same situation occurred during walking, but the thermal power of the TM&C system was insufficient to overcome heat build-up in some regions of the residual limb. The participant reported no significant change of thermal sense and thermal comfort. Further investigations are warranted to examine thermography pattern of the residual limb, thermal sense, and thermal comfort in people with amputation.

Correlations between Berg balance scale and gait speed in individuals with stroke wearing ankle-foot orthoses - a pilot study.

PURPOSE: The Berg balance scale (BBS) is commonly used to assess balancing ability in patients with stroke. The BBS may be a good candidate for clinical assessment prior to orthotic intervention, if it correlates well with outcome measures such as gait speed. The purpose of this study was to investigate the correlation between the BBS measured prior to walking with an ankle-foot orthosis (AFO) and specific temporal-spatial parameters of gait when walking with an AFO donned. METHODS: Eight individuals with chronic stroke participated in this study. Balancing ability was assessed using the BBS, while temporal-spatial parameters of gait (gait speed, bilateral step length, stride length and step width) were measured using a three-dimensional motion analysis system. The correlations between the BBS and gait parameters were investigated using a non-parametric Kendall's Tau (τ) correlation analysis. RESULTS: The BBS showed correlations with gait speed (τ = 0.64, p < 0.05), the step length of the affected side (τ = 0.74, p < 0.05), and the stride length (τ = 0.64, p < 0.05). CONCLUSIONS: Assessment of the BBS prior to AFO prescription may potentially help clinicians to estimate the gait speed achievable following orthotic intervention in patients with stroke. Implications for Rehabilitation Assessment of the BBS prior to AFO prescription may help orthotists to estimate the gait speed following an orthotic intervention in patients with stroke. Assessment of the BBS prior to AFO prescription may help orthotists to understand overall balance and postural control abilities in patients with stroke. A larger scale multifactorial analysis is warranted to confirm the results of this pilot study.

Effects of heel lifting on transtibial amputee gait before and after treadmill walking: a case study.

BACKGROUND: Prosthetic alignment is usually unchanged once optimized. However, a previous study indicated that long-distance walking significantly altered gait patterns, suggesting some alignment adjustments after walking are required. This study investigated the effects of alignment changes (by inserting a heel lift) on gait of a transtibial amputee before and after treadmill walking. CASE DESCRIPTION AND METHODS: The subject walked, without heel lifts, on a treadmill until perception of fatigue. Gait changes upon heel lifting at the prosthetic side were studied before and after the treadmill walking FINDINGS AND OUTCOMES: For this subject before the treadmill walking, heel lifting induced drop-off with increased prosthetic-side knee flexion at mid-stance and pre-swing. The sound limb outreached to stabilize the gait. After the treadmill walking, the same heel lift did not induce drop-off. It reduced the plantar flexor power generation, potentially delaying its fatigue. CONCLUSION: After walking prosthetic-side heel lifting could be beneficial. CLINICAL RELEVANCE: Many lower-limb amputees have difficulties in long-distance walking due to muscle fatigue. This case study proposes that appropriate alignment changes after some walking potentially relieve fatigue and encourage them to walk longer distances.

Effects of long-distance walking on socket-limb interface pressure, tactile sensitivity and subjective perceptions of trans-tibial amputees.

PURPOSE: Many trans-tibial amputees could not tolerate long-distance walking. Lack of walking could explain for the increased cardiovascular diseases mortality rate. This study investigated the effects of long-distance walking (LDW) on socket-limb interface pressure, tactile sensitivity of the residual limb, and subjective feedbacks, which potentially identified the difficulties in LDW. METHOD: Five male unilateral trans-tibial amputees walked on a level treadmill for a total of one hour at comfortable speed. Tactile sensitivity of the residual limb and socket-limb interface pressure during over-ground walking were measured before and after the treadmill walking. Modified Prosthesis Evaluation Questionnaires were also administered. RESULTS: After the treadmill walking, the socket-limb interface pressure and the tactile sensitivity at the popliteal depression area were significantly reduced. This corresponds well with the questionnaire results showing that the level of discomfort and pain of the residual limb did not increase. The questionnaire revealed that there were significant increases in fatigue level at the sound-side plantar flexors, which could lead to impaired dynamic stability. CONCLUSIONS: Fatigue of sound-side plantar-flexor was the main difficulty faced by the five subjects when walking long-distances. This finding might imply the importance of refining prosthetic components and rehabilitation protocols in reducing the muscle fatigue. IMPLICATIONS FOR REHABILITATION: • After long-distance walking (LDW) of the trans-tibal amputee subjects, there were significant increases in fatigue level at the plantar flexors. These might explain the reduced walking stability as perceived by the subjects. • LDW did not produce any problems in residual-limb comfort and pain feeling. These were in line with the significant reductions of socket-limb interface pressure and the tactile sensitivity at the popliteal depression after LDW. • Refinements of prosthetic components and rehabilitation protocols should be attempted to reduce the fatigue of the plantar flexors and facilitate LDW.

The effect of varying the plantarflexion resistance of an ankle-foot orthosis on knee joint kinematics in patients with stroke.

Ankle-foot orthoses (AFOs) can improve gait in patients with hemiplegia. However, it is anecdotally known that excessive plantarflexion resistance of an AFO could induce undesired knee flexion at early stance. The aim of this study was to systematically investigate the effect of varying the degrees of plantarflexion resistance of an AFO on knee flexion angles at early stance in five subjects with chronic stroke who demonstrated two clear knee flexion peaks at early stance and swing. Each subject wore an experimental AFO constructed with an oil-damper type ankle joint and was instructed to walk at their self-selected walking speed under five plantarflexion resistance conditions. The sagittal plane ankle and knee joint kinematics and gait speed were analyzed using a 3-D Motion Analysis System. A number of significant differences (P<0.005) in maximum knee flexion angles at early stance amongst different plantarflexion resistance conditions were revealed. The knee flexion angle was 23.80 (3.25) degrees under the free hinge joint condition (condition 1), while that was 26.09 (3.79) degrees under the largest resistance condition (condition 5). It was therefore demonstrated that increasing the plantarflexion resistance of an AFO would induce more knee flexion at early stance phase in patients with stroke.

Is it important to position foot in subtalar joint neutral position during non-weight-bearing molding for foot orthoses?

When taking molds for foot orthoses, it is accepted practice to position the subtalar joint in its neutral position. However, foot orthoses have no contact with the talus, and this leads to a hypothesis that as long as there is correction available to appropriately align the forefoot relative to the hindfoot when taking a mold, changes in subtalar joint angles do not lead to significant alterations in the plantar surface shapes of the molds taken. This study tested this presumption with 20 subjects between 22 and 46 years old. During non-weight-bearing casting, the subtalar joints were aligned at positions of 4° of eversion, 2° of eversion, 2° of inversion, and in neutral. At each orientation, forces were applied over the forefoot such that the metatarsal heads were aligned with the rearfoot. Digital scanning was used to analyze the shape of each negative mold. There were significant changes in projection volume in different subtalar joint orientations. However, the changes in arch heights, navicular height, and protrusion were insignificant and very small. It is therefore suggested that as long as the forefoot and hindfoot are appropriately aligned, variations in the orientation of the subtalar joint would be acceptable.

Effect of ankle-foot orthoses on the sagittal plane displacement of the center of mass in patients with stroke hemiplegia: a pilot study.

BACKGROUND: Ankle-foot orthoses (AFOs) have been reported to have positive effects on the temporal-spatial parameters and kinematics and kinetics of gait in patients with stroke. The center of mass (COM) may be used to represent whole body movement and energy cost in gait, and therefore COM movement would also be positively influenced with use of an appropriate AFO. OBJECTIVE: To investigate the effect of AFOs on the sagittal plane displacement of the COM in patients with stroke hemiplegia. METHODS: Five male subjects with stroke hemiplegia participated in this pilot study. The trajectory of the COM in the sagittal plane, gait speed, bilateral step length, step width, and bilateral stance time were analyzed while participants ambulated under 2 test conditions: with an AFO or with footwear only. The height of the 2 peaks of the vertical displacement of the COM in a gait cycle was subsequently measured and normalized to body height. Statistical analyses were conducted using a nonparametric Friedman test. RESULTS: Gait speed, bilateral step length, and the normalized peak height of the vertical COM trajectory during stance phase on the affected leg all revealed statistically significant increases (P < .05), and step width showed significant decreases (P < .05) under the AFO condition when compared to the footwear-only condition. CONCLUSIONS: An AFO may influence the vertical displacement of the COM in patients with stroke hemiplegia. The results of this pilot study therefore suggested that vertical movement of COM could potentially serve as a useful parameter to evaluate the effect of an AFO.

Comparison of custom-moulded ankle orthosis with hinged joints and off-the-shelf ankle braces in preventing ankle sprain in lateral cutting movements.

BACKGROUND: A custom moulded ankle orthosis with hinged joints potentially offers a better control over the subtalar joint and the ankle joint during lateral cutting movements, due to total contact design and increase in material strength. OBJECTIVES: To test the above hypothesis by comparing it to three other available orthoses. STUDY DESIGN: Repeated measures. METHODS: Eight subjects with a history of ankle sprains (Grade 2), and 11 subjects without such history performed lateral cutting movements in four test conditions: 1) non-orthotic, 2) custom-moulded ankle orthosis with hinges, 3) Sport-Stirrup, and 4) elastic ankle sleeve with plastic support. A VICON motion analysis system was used to study the motions at the ankle and subtalar joints. RESULTS: The custom-moulded ankle orthosis significantly lowered the inversion angle at initial contact (p = 0.006) and the peak inversion angle (p = 0.000) during lateral cutting movements in comparison to non-orthotic condition, while the other two orthoses did not. The three orthoses did not affect the plantarflexion motions, which had been suggested by previous studies to be important in shock wave attenuation. CONCLUSIONS: The custom-moulded ankle orthosis with hinges could better control inversion and thus expected to better prevent ankle sprain in lateral cutting movements. CLINICAL RELEVANCE: Custom-moulded ankle orthoses are not commonly used in preventing ankle sprains. This study raises the awareness of the use of custom-moulded ankle orthoses which are expected to better prevent ankle sprains.

Long-distance walking effects on trans-tibial amputees compensatory gait patterns and implications on prosthetic designs and training.

Trans-tibial amputees are advised to walk as much as able people to achieve healthy and independent life. However, they usually have difficulties in doing so. Previous researches only included data from a few steps when studying the gait of amputees. Walking over a long distance was rarely examined. The objective of this study was to investigate the changes in spatial-temporal, kinetic and kinematic gait parameters of trans-tibial amputees after long-distance walking. Six male unilateral trans-tibial amputees performed two sessions of 30-min walking on a level treadmill at their self-selected comfortable speed. Gait analysis was undertaken over-ground: (1) before walking, (2) after the 1st walking session and (3) after the 2nd walking session. After the long-distance walking, changes in spatial-temporal gait parameters were small and insignificant. However, the sound side ankle rocker progression and push-off were significantly reduced. This was due to the fatigue of the sound side plantar flexors and was compensated by the greater effort in the prosthetic side. The prosthetic side knee joint showed significantly increased flexion and moment during loading response to facilitate the anterior rotation of the prosthetic shank. The prosthetic side hip extensors also provided more power at terminal stance to facilitate propulsion. Endurance training of the sound side plantar flexors, and improvements in the prosthetic design to assist anterior rotation of the prosthetic shank should improve long-distance walking in trans-tibial amputees.

Effectiveness of adjustable dorsiflexion night splint in combination with accommodative foot orthosis on plantar fasciitis.

Foot orthoses and night splints have been used separately to treat patients with plantar fasciitis, but were not always successful. Combined use of both orthoses might give better outcomes. This study evaluated the effectiveness of a soft and self-adjustable dorsiflexion night splint in combination with an accommodative foot orthosis for patients with plantar fasciitis. Twenty-eight patients were assigned to group A (foot orthosis only) and group B (combination of foot orthosis and dorsiflexion night splints). A foot function index (FFI) questionnaire was used to evaluate the pain and functions of feet just before, 2 weeks after, and 8 weeks after the treatments. Results showed that subjects in group B had significantly reduced pain scores at week 2 (p < 0.001) and week 8 (p < 0.001). In group A, no statistical differences were noted in the pain (p = 0.15), disability (p = 0.56), activity limitation (p = 0.75), and total FFI (p = 0.35) scores for the three time periods. The application of foot orthoses with adjustable dorsiflexion night splints was found to be more effective than the application of foot orthoses alone in relieving foot pain in patients with plantar fasciitis.

Techniques to measure rigidity of ankle-foot orthosis: a review.

We performed this review to provide a clearer understanding of how to effectively measure ankle-foot orthosis (AFO) rigidity. This information is important to ensure appropriate orthotic intervention in the treatment of patients with pathological gait. The two main approaches to the investigation of AFO rigidity are (1) bench-testing analyses, in which an AFO is fixed or attached to a measurement device, and (2) functional analyses, in which measurements are taken while a subject is walking with an AFO in situ. This review summarizes and classifies the current state of knowledge of AFO rigidity testing methods. We analyzed the strengths and weaknesses of the methods in order to recommend the most reliable techniques to measure AFO rigidity. The information obtained from this review article would, therefore, benefit both clinicians and engineers involved in the application and design of AFOs.

Effect of heel height on in-shoe localized triaxial stresses.

Abnormal and excessive plantar pressure and shear are potential risk factors for high-heeled related foot problems, such as forefoot pain, hallux valgus deformity and calluses. Plantar shear stresses could be of particular importance with an inclined supporting surface of high-heeled shoe. This study aimed to investigate the contact pressures and shear stresses simultaneously between plantar foot and high-heeled shoe over five major weightbearing regions: hallux, heel, first, second and fourth metatarsal heads, using in-shoe triaxial force transducers. During both standing and walking, peak pressure and shear stress shifted from the lateral to the medial forefoot as the heel height increased from 30 to 70mm. Heel height elevation had a greater influence on peak shear than peak pressure. The increase in peak shear was up to 119% during walking, which was about five times that of peak pressure. With increasing heel height, peak posterolateral shear over the hallux at midstance increased, whereas peak pressure at push-off decreased. The increased posterolateral shear could be a contributing factor to hallux deformity. It was found that there were differences in the location and time of occurrence between in-shoe peak pressure and peak shear. In addition, there were significant differences in time of occurrence for the double-peak loading pattern between the resultant horizontal ground reaction force peaks and in-shoe localized peak shears. The abnormal and drastic increase of in-shoe shear stresses might be a critical risk factor for shoe-related foot disorders. In-shoe triaxial stresses should therefore be considered to help in designing proper footwear.

Design of a stiffness-adjustable ankle-foot orthosis and its effect on ankle joint kinematics in patients with stroke.

Ankle-foot orthoses (AFOs) are commonly prescribed to improve gait. The stiffness of an AFO is central for successful prescription; however, the recommended level of stiffness is currently based on the experience of clinicians. Therefore, the aim of this study was to design an experimental AFO (EAFO) whose stiffness was adjustable using commercially available oil-damper joints, and to demonstrate its potential capability in investigating the effects of altering AFO stiffness on gait. The influence of the EAFO stiffness on ankle joint kinematics in sagittal plane was evaluated in 10 patients with stroke by altering the stiffness of its oil-damper- type orthotic ankle joints using the four levels pre-set and defined by the manufacturer in dorsi- and plantarflexion directions independently. The mean peak plantarflexion angle was reduced by 105%, showing a change from 8.18 (3.14) degrees of plantarflexion to 0.38 (4.17) degrees of dorsiflexion, whilst the mean peak dorsiflexion angle was reduced by 44%, showing a change from 11.46 (5.57) degrees of dorsiflexion to 6.47 (5.23) degrees of dorsiflexion by altering the EAFO stiffness. The EAFO would therefore serve as a convenient tool when investigating the influence of AFO stiffness on gait in both clinical and research settings.

Evaluating the contribution of a neural component of ankle joint resistive torque in patients with stroke using a manual device.

PRIMARY OBJECTIVE: To investigate the methodology using a manual ankle joint resistive torque measurement device to evaluate the contribution of the neural component of ankle joint resistive torque in patients with stroke. RESEARCH DESIGN: Within-subject comparison to compare the ankle joint resistive torque between fast and slow stretching conditions. METHODS AND PROCEDURES: Ten patients with stroke participated in this study. The incremental ratio of ankle joint resistive torque at the ankle angular position of 5degrees dorsiflexion under the fast stretching condition in comparison to the slow one was calculated in each patient. MAIN OUTCOMES AND RESULTS: A significant increase (p<0.01) in the ankle joint resistive torque was demonstrated under the fast stretching condition in comparison to the slow one in all patients and the mean ankle joint resistive torque was 4.6 (SD=1.7) Nm under the slow stretching condition, while it was 8.4 (SD=4.1) Nm under the fast stretching condition at the ankle angular position of 5 degrees dorsiflexion. The incremental ratio ranged from 9.4-139.3% among the patients. CONCLUSIONS: The results of this study demonstrated the potential advantage of the device to evaluate the contribution of the neural component of ankle joint resistive torque.

Design of an automated device to measure sagittal plane stiffness of an articulated ankle-foot orthosis.

The purpose of this study was to design a new automated stiffness measurement device which could perform a simultaneous measurement of both dorsi- and plantarflexion angles and the corresponding resistive torque around the rotational centre of an articulated ankle-foot orthosis (AAFO). This was achieved by controlling angular velocities and range of motion in the sagittal plane. The device consisted of a hydraulic servo fatigue testing machine, a torque meter, a potentiometer, a rotary plate and an upright supporter to enable an AAFO to be attached to the device via a surrogate shank. The accuracy of the device in reproducing the range of motion and angular velocity was within 4% and 1% respectively in the range of motion of 30° (15° plantarflexion to 15° dorsiflexion) at the angular velocity of 10°/s, while that in the measurement of AAFO torque was within 8% at the 0° position. The device should prove useful to assist an orthotist or a manufacturer to quantify the stiffness of an AAFO and inform its clinical use.