Gait & Posture - Articles in Press

Kinematic adaptations of the hindfoot, forefoot, and hallux during cross-slope walking - Corrected Proof

Mohsen Damavandi, Philippe C. Dixon, David J. Pearsall — 2010-07-28

Abstract: Despite cross-slope surfaces being a regular feature of our environment, little is known about segmental adaptations required to maintain both balance and forward locomotion. The purpose of this study was to determine kinematic adaptations of the foot segments in relation to transverse (cross-sloped) walking surfaces. Ten young adult males walked barefoot along an inclinable walkway (level, 0° and cross-slope, 10°). Kinematic adaptations of hindfoot with respect to tibia (HF/TB), forefoot with respect to hindfoot (FF/HF), and hallux with respect to forefoot (HX/FF) in level walking (LW), inclined walking up-slope (IWU), i.e., the foot at the higher elevation, and inclined walking down-slope (IWD), i.e., the foot at the lower elevation, were measured. Multivariate analysis of variance (MANOVA) for repeated measures was used to analyze the data. In the sagittal plane, the relative FF/HF and HX/FF plantar/dorsiflexion angles differed across conditions (p=0.024 and p=0.026, respectively). More importantly, numerous frontal plane alterations occurred. For the HF/TB angle, inversion of IWU and eversion of IWD was seen at heel-strike (p<0.001). This pattern reversed with IWU showing eversion and IWD inversion in early stance (p=0.024). For the FF/HF angle, significant differences were observed in mid-stance with IWD revealing inversion while IWU was everted (p<0.004). At toe-off, the pattern switched to eversion of IWD and inversion of IWU (p=0.032). The information obtained from this study enhances our understanding of the kinematics of the human foot in stance during level and cross-slope walking.

Independent influence of gait speed and step length on stability and fall risk - Corrected Proof

D.D. Espy, F. Yang, T. Bhatt, Y.-C. Pai — 2010-07-26

Abstract: With aging, individuals’ gaits become slower and their steps shorter; both are thought to improve stability against balance threats. Recent studies have shown that shorter step lengths, which bring the center of mass (COM) closer to the leading foot, improve stability against slip-related falls. However, a slower gait, hence lower COM velocity, does the opposite. Due to the inherent coupling of step length and speed in spontaneous gait, the extent to which the benefit of shorter steps can offset the slower speed is unknown. The purpose of this study was to investigate, through decoupling, the independent effects of gait speed and step length on gait stability and the likelihood of slip-induced falls. Fifty-seven young adults walked at one of three target gait patterns, two of equal speed and two of equal step length; at a later trial, they encountered an unannounced slip. The results supported our hypotheses that faster gait as well as shorter steps each ameliorates fall risk when a slip is encountered. This appeared to be attributable to the maintenance of stability from slip initiation to liftoff of the recovery foot during the slip. Successful decoupling of gait speed from step length reveals for the first time that, although slow gait in itself leads to instability and falls (a one-standard-deviation decrease in gait speed increases the odds of fall by 4-fold), this effect is offset by the related decrease in step length (the same one-standard-deviation decrease in step length lowers fall risk by 6 times).

Leg extension is an important predictor of paretic leg propulsion in hemiparetic walking - Corrected Proof

Carrie L. Peterson, Jing Cheng, Steven A. Kautz, Richard R. Neptune — 2010-07-26

Abstract: Forward propulsion is a central task of walking that depends on the generation of appropriate anterior–posterior ground reaction forces (AP GRFs). The AP impulse (i.e., time integral of the AP GRF) generated by the paretic leg relative to the non-paretic leg is a quantitative measure of the paretic leg's contribution to forward propulsion and is variable across hemiparetic subjects. The purpose of this study was to investigate the underlying mechanisms of propulsion generation in hemiparetic walking by identifying the biomechanical predictors of AP impulses.Three-dimensional kinematics and GRFs were recorded from 51 hemiparetic and 21 age-matched control subjects walking at similar speeds on an instrumented treadmill. Hierarchical regression models were generated for each leg to predict the AP impulse from independent biomechanical variables.Leg extension was a significant predictor and positively related to the propulsive impulse in the paretic, non-paretic and control legs. Secondarily, the hip flexor moment impulse was negatively related to the propulsive impulse. Also, the relationship of paretic and non-paretic ankle moments with the propulsive impulse depended on the paretic step ratio, suggesting the plantar flexor contribution to the propulsive impulse depends on leg angle. These results suggest that increasing paretic leg extension will increase propulsion. Increasing paretic plantar flexor output and decreasing paretic hip flexor output could also increase paretic leg propulsion. While increased pre-swing hip flexor output has been suggested to compensate for decreased plantar flexor output, such output may further impair propulsion by the paretic leg if it occurs too soon in the gait cycle.

Torsional profile versus gait analysis: Consistency between the anatomic torsion and the resulting gait pattern in patients with rotational malalignment of the lower extremity - Corrected Proof

2010-07-26

Abstract: Measurements of femoral and tibial torsion obtained from radiographs or computed tomographic scans have been used to describe rotational malalignment of the lower extremities and to clarify indications for surgery. A weak relationship between anatomic torsion deformity and the resulting transverse plane gait pattern in patients with cerebral palsy has been described, but the observations have not yet been tested in an able-bodied patient population. We conducted a prospective study to investigate the correlation of femoral torsion and tibial torsion as measured by using computed tomography with transverse plane gait data for patients with rotational malalignment. Twenty-six lower limbs from 26 patients selected for surgery based on gait analysis were evaluated. Calculation of Pearson correlations showed that increase of femoral anteversion resulted in increase of pelvic range of motion. A very weak correlation between femoral torsion and hip rotation (determination coefficient, R2=0.22) was found in a linear regression model, whereas tibial torsion and knee rotation showed a strong correlation (determination coefficient, R2=0.71). The correlation between the foot progression angle and tibial torsion was higher than between the foot progression angle and femoral torsion. We conclude that there is a considerable dynamic influence of mechanisms of compensation, especially in the hip, that should be considered when evaluating the torsional profile. We therefore recommend conducting three-dimensional instrumented gait analysis for patients undergoing surgical correction of rotational malalignment.

A cross-sectional study about the relationship between morphology and step-time parameters in children between 15 and 36 months - Corrected Proof

M. Van Dam, A. Hallemans, S. Truijen, P. Aerts — 2010-07-26

Abstract: Morphology and step-time parameters were recorded in 100 children between 15 and 36 months to investigate the relation between morphology and the walking pattern. A footfall method was used to register step-time parameters. Next, the differences in step-time parameters between four morphological classes were assigned with a multiple analysis of variance. We also performed stepwise linear regressions with a correction for walking experience, to examine the relation between detailed morphological measurements and step-time parameters. The results of these regressions show a significant relation between pelvis span/ankle spread ratio and the relative radii of gyration in the frontal plane of head and pelvis. It is hypothesized that the morphology of the head and pelvis plays a role in the coordination of the walking pattern.

Test–retest reliability of step counts with the ActivPAL™ device in common daily activities - Corrected Proof

2010-07-23

Abstract: The ActivPAL device is a well-established physical activity monitor for assessment of physical activity. Aim: To investigate test–retest reliability of step counts and establish minimal detectable changes (MDC) in step count to account for intra device error over time in various physical activities. Methods: Healthy participants (n=24, age range, 19–28 years) performed activities on two occasions, 1 week apart, in a laboratory setting; self-paced floor walking, treadmill walking at three different speeds (3.2km/h, 4.5km/h and 4.5km/h with incline), treadmill jogging (8.0km/h), stair walking and cycling on an exercise bike at three speeds (45rpm, 60rpm and 75rpm). Relative reliability was calculated using intraclass correlation coefficient (ICC) and Spearman correlation. Absolute reliability was assessed using standard error of measurement (SEM) and coefficient of repeatability (CR). Results: The ActivPAL showed high to very high relative reliability for treadmill walking at all speeds and stair walking, while self-paced normal floor walking showed moderate reliability. The absolute reliability was the best for treadmill walking activities, slightly increased for self-paced walking, followed by stair walking and jogging. The use of activity monitors during cycling has been questioned and our results confirm a low absolute and relative reliability. MDC values varied according to the type of activity e.g. treadmill walking 4.5km/h (10 steps), walking on the floor (45 steps). Data loss in this study (10–13%) was higher than previously reported. Conclusions: The ActivPAL is reliable for treadmill walking, jogging and self-paced walking. MCD varies according to the activity and should be considered when establishing true change over time.

Normal pressure values and repeatability of the Emed® ST2 system - Corrected Proof

M. Maetzler, T. Bochdansky, R.J. Abboud — 2010-07-22

Abstract: Objectives: This study was designed to assess the repeatability of the Emed® ST2 system and identify the range of pressure values observed in the normal foot.Methods: Measurements were taken from twenty-three healthy subjects, 14 females and 9 males, on two occasions 7 days apart. Begin of contact (BC), end of contact (EC), contact time (CT), peak pressure (PP), instant of peak pressure (IPP), contact area (CA) and pressure–time integral (PTI) were recorded.Results: The coefficient of repeatability (CR) was less than 16.0% for all 63 parameters considered. In 87.3% of the parameters investigated (55 of 63) the CR (expressed as a percentage of the mean) was less than 10%. The highest areas of PP were found under the great toe and second metatarsal heads, with mean (S.D.) equal to 435kPa (202) and 407kPa (146), respectively, followed by the third metatarsal head 345kPa (96) and the hindfoot 332kPa (93). The CT (% ROP (range of pressure)) was in the range 74–85% under the metatarsal heads, and 71% under the great toe. CA was highest under the heel at 33.8cm2.Conclusion: Emed® ST2 system was found to be repeatable. The presented range of parameters compared very well to the results presented in the literature for the Emed® ST4 system.

Plantar pressures determinants in mild Hallux Valgus - Corrected Proof

2010-07-21

Abstract: While podobarometric techniques have been applied to the study of pressures in Hallux Valgus (HV), little is known about its clinical and radiological determinants. So, the aim of the present study was to determine the plantar pressure pattern in participants with mild HV, comparing to a control group, and their clinical and anthropometric determinants. Biofoot/IBV® in-shoe system was used to evaluate 79 participants with mild HV. Computerized measurements of the 1st intermetatarsal angle (IMA) and the hallux abductus angle (HAA) were made on antero-posterior radiographs. The clinical outcome was assessed using the AOFAS score. The dependent baropodometric variables and the independent clinical and anthropometric variables were subjected to a multiple regression analysis. In both groups, the highest average pressure was in the 2nd metatarsal head (MTH). The mean pressure under the Hallux was significantly higher in HV group (controls, 146.5±92.5kPa; HV, 328.5±113.2kPa; p<0.001). An 18.6% of average pressure under the 1st MTH was accounted for pain, first ray alignment and total AOFAS score. Variations of the HAA explained 26.8% of the mean Hallux pressure. Women with mild HV present with pathologically increased pressure under the Hallux, which is caused by the altered alignment of the first ray. Pain and clinical result were associated with the pressure under the 1st MTH and the remaining variables were only moderate predictors of dynamic plantar pressures.

Lateral ankle ligament anesthesia significantly alters single limb postural control - Corrected Proof

P.O. McKeon, M.J. Booi, B. Branam, D.L. Johnson, C.G. Mattacola — 2010-07-21

Abstract: Lateral ankle anesthesia has been used as a model to explore effects of ligament deafferentation related to ankle sprain on single limb postural control with conflicting results. Time-to-boundary (TTB) is a postural control measurement technique found to be sensitive in detecting subtle deficits in postural control in those with chronic ankle instability. The objective of this study was to determine the effects of lateral ankle ligament anesthesia on TTB measures of single limb postural control in healthy adults. Twenty-two healthy adults with no history of lower extremity injury within the past 6 months or balance disorders participated in the study. All subjects received a lidocaine injection to the lateral ankle structures on one of two testing days. On both testing days, subjects performed 3 eyes open and 3 eyes closed, 10-s trials of barefoot single limb stance on a forceplate. The dependent variables were the mean of TTB minima(s) and standard deviation of TTB minima(s) in mediolateral (ML) and anteroposterior (AP) directions. Separate condition (anesthesia, control) by vision (eyes open, eyes closed) ANOVAs with repeated measures were used for each TTB variable to determine the effects of anesthesia on postural control. Alpha level was set a priori at p≤0.05. The anesthesia day TTBAP magnitude (p=0.008) and variability (p=0.044) measures were significantly lower than the control day, regardless of vision. Anesthesia of the lateral ankle ligamentous structures significantly reduced the magnitude and variability of TTBAP measures. These findings are similar to deficits found in those with chronic ankle instability.

Moiré topography: Characteristics and clinical application - Corrected Proof

2010-07-21

Abstract: Since 1970, the Moiré phenomenon has been employed as a method of clinical diagnosis in topographical analyses of the human body. The objective of this study was to review the literature on the main characteristics of the Moiré phenomenon and its use as a topographical method for clinical applications, particularly those related to postural deviations. A systematic search for papers written in English between 1966 and 2010 was performed according to pre-established selection criteria and the selected studies underwent a content analysis. The results showed an evolution in the method of Moiré topography (MT), which reflect an increasing effort to improve the accuracy and precision of the method, as well as to facilitate the interpretation of topograms using specific software. The Shadow and Projection Moiré techniques have more frequently been used in comparison with other techniques. On the other hand, the methodological procedures of MT are apparently not well defined in the literature. Although MT was shown to be useful in the detection of spinal deformities, there is still a lack of research in clinical settings, especially in the elderly. For the most part, the studies involve the tracking of scoliosis in school age children. Japan appears to be the most advanced country in terms of the application of MT.

Perceived pain, fear of falling and physical function in women with osteoporosis - Corrected Proof

Markus Hübscher, Lutz Vogt, Katharina Schmidt, Matthias Fink, Winfried Banzer — 2010-07-21

Abstract: The aim of this cross-sectional study was to evaluate pain intensity-related differences in physical performance and fear of falling in elderly women with osteoporosis. A sample of 82 osteoporotic women (73.8±8.1 years) with and without vertebral fractures was included. Numeric rating scale (NRS) measures (0=no pain, 10=unbearable) were applied to obtain actual pain intensity and to stratify between patients with mild (0–3), moderate (4–6) and severe (7–10) pain. Activity-related fear of falling was evaluated with the Falls Efficacy Scale-International Version (FES-I). Physical performance measures included maximum voluntary quadriceps strength, postural sway and gait speed measures. Controlling for age, fractures, and history of falls ANCOVA with Scheffe's post hoc test indicated significant slower walking velocities and greater postural sway for patients with severe pain. Furthermore, significant group differences could be detected for muscle strength and fear of falling. Patients with more intense pain (NRS≥5) were 6.4 times (odds ratio; 95%CI: 1.5–26.7) more likely to score below average in fall-related self-efficacy and all physical performance tests. Among women with osteoporosis, heightened back pain intensity increases fear of falling and decreases physical performance irrespective of vertebral fractures and history of falls.

Does human gait exhibit comparable and reproducible long-range autocorrelations on level ground and on treadmill? - Corrected Proof

2010-07-16

Abstract: Stride duration of young healthy subjects walking at spontaneous speed fluctuates over the long-term in a very complex way. The presence of long-range autocorrelations among these fluctuations has already been highly suggested for subjects walking on level ground, but the mathematical methods used among studies are variable. Moreover, despite the frequent use of a treadmill in research and in rehabilitation, the presence of such autocorrelations was nearly exclusively assessed during level-ground walking.The first aim of this study was to confirm the presence of long-range autocorrelations among stride duration variability on level ground with a good level of confidence. The stride duration fluctuations of 10 young healthy subjects were assessed on a 37-meter-long track using an integrated approach that combines the results of rescaled range analysis and power spectral analysis. Secondly, the results obtained from treadmill tests were compared with the outcomes of the level-ground walking tests in order to challenge the persistence of the long-range autocorrelations during treadmill walking. Finally, the third aim of this study was to test the reproducibility of the outcomes by comparing the results obtained on the treadmill during two different trials.The outcomes of this study provide significant evidence to confirm the hypothesis that long-range autocorrelations are present among stride duration variability, not only on level ground but also on the treadmill. The reproducibility of the results obtained during treadmill walking further validates the use of a treadmill to assess the long-term fluctuations of gait.

Suspected feigned knee extensor weakness: Usefulness of 3D gait analysis. Case report - Corrected Proof

Joaquim Chaler, Bertram Müller, Anna Maiques, Eduard Pujol — 2010-07-15

Abstract: The purpose of the present case report is to show the potential for use of 3D gait analysis as an assessment method of feigned muscle weakness.We describe a patient complaining of right leg pain and weakness. Physical examination showed severe quadriceps muscle weakness in a highly abnormal gait pattern context. Conventional diagnostic workup did not show any relevant findings. Three-dimensional (3D) gait analysis was performed with a 3D motion capture system. Joint angles, internal moments and powers were computed from the motion data. Lower leg muscle surface-electromyography was also performed. During the late stance phase, flexor moment and negative power peaks (indicating eccentric knee extensor activity) were generated in the knee, together with relevant Rectus femoris activity. All findings were highly inconsistent with true quadriceps weakness and gave objective ground to suspect insincerity of patient complaints. 3D gait analysis might be a valuable clinical assessment tool in suspected feigned lower limb muscle weakness.

Principal component analysis detects sleepiness-related changes in balance control - Corrected Proof

Pia Forsman, Edward Hæggström, Anders E. Wallin, Esko Toppila, Ilmari Pyykkö — 2010-07-15

Abstract: Computerized posturography exploits balance scores that quantify the size, dynamics, or structure of the recorded sway. Since people employ different balance strategies, one single balance score will not detect balance changes in all subjects. Principal component analysis (PCA) can combine balance scores that quantify different features into one new balance score. We tested the score with 20 subjects by measuring their balance every 2h during 28h of sustained waking. The new balance score was more sensitive than its components (p<0.001 vs. p≥0.051) to the small sleepiness-related balance decrements that occurred during the short 28-h period. PCA provided a more sensitive balance score that applied to all of the subjects.

Gait pathology assessed with Gillette Gait Index in patients after CNS tumour treatment - Corrected Proof

2010-07-14

Abstract: Brain tumour is the third leading cause of death in children and adolescents younger than 16 years of age. The increasing survival rate of these patients makes their follow-up and quality of life assessment an important task. This study evaluated the gait pathology of the patients after the combined treatment for central nervous system (CNS) tumours. It assessed if the severity of gait deviation depended on the tumour site or age of illness onset. Gait analysis was performed on patients who completed the treatment (neurosurgery, chemo- and radiotherapy) and were disease-free at the time of the study. One hundred and five patients, 42 girls and 63 boys, aged 5–24 years of age, participated in the study. Depending on the location of the tumour, patients were divided into six groups.The Gillette Gait Index (GGI) was used to quantify gait deviation of patients compared to healthy subjects. Gait analysis was undertaken using VICON 460 movement analysis system. The Helen Hayes marker set was used, together with the Vicon Plug-in-Gait model. For each child the GGI was calculated separately for the left and right legs using data extracted from the subjects’ averaged data. The results from left and right legs were then pooled together. To determine the effect of the tumour site and the onset of illness the ANOVA Kruskal–Wallis and correlation tests were used.The GGI did not depend on the tumour site, but demonstrated significant gait pathology in all patients. The age of illness onset appeared to influence the severity of gait deviation.

Balance recovery after an evoked forward fall in unilateral transtibial amputees - Corrected Proof

Carolin Curtze, At L. Hof, Bert Otten, Klaas Postema — 2010-07-07

Abstract: Falls are a common and potentially dangerous event, especially in amputees. In this study, we compared the mechanisms of balance recovery of 17 unilateral transtibial amputees and 17 matched able-bodied controls after being released from a forward-inclined orientation of 10%. Kinematic analysis revealed statistically significant differences in response time and knee flexion at heel-strike between both groups. However, there were no statistically significant differences in step length of the leading and trailing limb, swing time of the leading limb, and maximal knee flexion during swing.In the amputees, we found spatial and temporal differences when recovering with the sound versus prosthetic limb first. When leading with the prosthetic limb, they responded faster and also the interval between heel-strike of the leading and trailing limb was shorter. Furthermore, amputees made a longer step and showed less knee flexion at heel-strike when leading with the prosthetic limb. Interestingly, amputees as a group had no specific limb preference, prosthetic or sound, to recover after a forward fall, despite the asymmetry in their locomotor system. Analyses of dynamic stability (extrapolated center of mass) revealed that the amputees were equally efficient in recovering from an impending fall as controls, irrespective whether they lead with their prosthetic or sound limb. We suggest that in amputee rehabilitation, balance recovery after a fall should be trained with both sides, as this can increase confidence in fall-prone situations.

Gait patterns comparison of children with Duchenne muscular dystrophy to those of control subjects considering the effect of gait velocity - Corrected Proof

Nathaly Gaudreault, Denis Gravel, Sylvie Nadeau, Sylvie Houde, Denis Gagnon — 2010-07-05

Abstract: 3D analysis of the gait of children with Duchenne muscular dystrophy (DMD) was the topic of only a few studies and none of these considered the effect of gait velocity on the gait parameters of children with DMD. Gait parameters of 11 children with DMD were compared to those of 14 control children while considering the effect of gait velocity using 3D biomechanical analysis. Kinematic and kinetic gait parameters were measured using an Optotrak motion analysis system and AMTI force plates embedded in the floor. The data profiles of children with DMD walking at natural gait velocity were compared to those of the control children who walked at both natural and slow gait velocities. When both groups walked at similar velocity, children with DMD had higher cadence and shorter step length. They demonstrated a lower hip extension moment as well as a minimal or absent knee extension moment. At the ankle, a dorsiflexion moment was absent at heel strike due to the anterior location of the center of pressure. The magnitude of the medio-lateral ground reaction force was higher in children with DMD. Despite this increase, the hip abductor moment was lower. Hip power generation was also observed at the mid-stance in DMD children. These results suggest that most of the modifications observed are strategies used by children with DMD to cope with possible muscle weakness in order to provide support, propulsion and balance of the body during gait.

Re-interpreting detrended fluctuation analyses of stride-to-stride variability in human walking - Corrected Proof

Jonathan B. Dingwell, Joseph P. Cusumano — 2010-07-05

Abstract: Detrended fluctuation analyses (DFA) have been widely used to quantify stride-to-stride temporal correlations in human walking. However, significant questions remain about how to properly interpret these statistical properties physiologically. Here, we propose a simpler and more parsimonious interpretation than previously suggested. Seventeen young healthy adults walked on a motorized treadmill at each of 5 speeds. Time series of consecutive stride lengths (SL) and stride times (ST) were recorded. Time series of stride speeds were computed as SS=SL/ST. SL and ST exhibited strong statistical persistence (α≫0.5). However, SS consistently exhibited slightly anti-persistent (α<0.5) dynamics. We created three surrogate data sets to directly test specific hypotheses about possible control processes that might have generated these time series. Subjects did not choose consecutive SL and ST according to either independently uncorrelated or statistically independent auto-regressive moving-average (ARMA) processes. However, cross-correlated surrogates, which preserved both the auto-correlation and cross-correlation properties of the original SL and ST time series successfully replicated the means, standard deviations, and (within computational limits) DFA α exponents of all relevant gait variables. These results suggested that subjects controlled their movements according to a two-dimensional ARMA process that specifically sought to minimize stride-to-stride variations in walking speed (SS). This interpretation fully agrees with experimental findings and also with the basic definitions of statistical persistence and anti-persistence. Our findings emphasize the necessity of interpreting DFA α exponents within the context of the control processes involved and the inherent biomechanical and neuro-motor redundancies available.

Walking while talking—Difficulties incurred during the initial stages of multiple sclerosis disease process - Corrected Proof

Alon Kalron, Zeevi Dvir, Anat Achiron — 2010-07-01

Abstract: Patients with multiple sclerosis (MS) frequently experience poor gait and/or cognitive impairment, even in the early stages of the disease. As gait is often executed simultaneously with different cognitive tasks, it is essential to test gait during a cognitive load. Therefore, the main objective of this study was to assess gait and gait variations while simultaneously performing a cognitive task in patients with a clinically isolated syndrome (CIS) suggestive of MS. Fifty-two CIS patients, aged 33.8±0.2 years with an Expanded Disability Status Scale (EDSS) score of 1.7±0.2 were included in the study. The control group consisted of 28 age- and gender-matched healthy subjects. Major spatio-temporal parameters were collected via an electronic walkway (GAITRite electronic walkway system). Participants were instructed to walk under three different conditions: normal, fast, and at a normal pace while performing the modified word list generation (WLG) test. Compared to healthy subjects, the CIS patients’ gait was slower and asymmetrical with a wider base of support. The combined walking and cognitive task was expressed in prolonged double support (% gait cycle) and reduced velocity in patients only. As these findings are associated with the very early phase of MS, it appears that the ongoing pathological disease process is already taking place with regard to gait abilities. Since in early MS patients, gait-cognitive dual tasking may lead to an increased risk of falling, this important function should be addressed by physical rehabilitation clinicians.

A regression method for strength comparisons in children - Corrected Proof

B.A. MacWilliams, A.L. Shuckra, T.P. Mavor — 2010-06-30

Abstract: A method to estimate means and variance of strength based on anthropometric data is presented. The method is applied using a database of 10 lower extremity strength measures recorded from 48 typically developing children with a handheld dynamometer. Seven anthropometric variables are considered, and the combination of height and BMI is determined as a set of variables best suited to model these muscle groups. This regression scheme accounts for 45–58% of the observed variance. A clinical example illustrating the utility of the method is presented.

Balance problems during obstacle crossing in children with Developmental Coordination Disorder - Corrected Proof

F.J.A. Deconinck, G.J.P. Savelsbergh, D. De Clercq, M. Lenoir — 2010-06-28

Abstract: The present study investigated the visuomotor and balance limitations during obstacle crossing in typically developing (TD) children and those with Developmental Coordination Disorder (DCD) (7–9 years old; N=12 per group). Spatiotemporal gait parameters as well as range and velocity of the centre of mass (COM) were determined in three conditions: overground walking at a self-selected speed, crossing a low obstacle and crossing a high obstacle (5% or 30% of the leg length, respectively). Both groups walked more slowly during obstacle crossing than walking over level ground. In addition, both groups exhibited a significant decrease in the spatial variability of their foot placements as they approached the obstacle, which was then negotiated with a similar strategy. There were no differences in approach distance, length of lead and trail step, or lead and trail foot elevation. Compared to walking over level ground, obstacle crossing led to a longer swing phase of the lead and trail foot and increased maximal medio-lateral COM velocity. In children with DCD, however, medio-lateral COM velocity was higher and accompanied by significantly greater medio-lateral COM amplitude. In conclusion, the results indicate that while TD-children and those with DCD exhibit satisfactory anticipatory control and adequate visual guidance, the latter group have a reduced ability to control the momentum of the COM when crossing obstacles that impose increased balance demands.

Identification of peripheral neuropathy in type-2 diabetic subjects by static posturography and linear discriminant analysis - Corrected Proof

S. Fioretti, M. Scocco, L. Ladislao, G. Ghetti, R.A. Rabini — 2010-06-25

Abstract: Background: An early diagnosis of peripheral neuropathy in diabetic patients is useful in order to slow down the progress of this complication. Nerve conduction tests are the gold standard for this diagnosis but they are challenging for the patients. This study examines whether it is possible to assess the presence of diabetic neuropathy at an early stage by static posturography tests.Methods: Static posturography tests were performed on 37 type-2 diabetic subjects (25 neuropathic patients and 12 non-neuropathic control subjects). Each subject was tested twice under two visual conditions: open and closed eyes. Both “global” (classic) and “structural” (model-based) posturographic parameters (PP) were derived from centre-of-pressure trajectories. A total of 65 PP were computed but only five were selected, normalized and fed to a linear classifier based on linear discriminant analysis.Results: This method correctly classified 86.5% of the patients. Five subjects were misclassified and only 2 false negatives out of 25 neuropathic subjects were erroneously diagnosed as control subjects.Conclusions: This paper shows that “global” and “structural” parameters derived by static posturography tests, and classic linear statistical approaches, can be used for the diagnosis of neuropathy provided PP are properly chosen and normalized.

Ambulatory assessment of 3D ground reaction force using plantar pressure distribution - Corrected Proof

H. Rouhani, J. Favre, X. Crevoisier, K. Aminian — 2010-06-24

Abstract: This study aimed to use the plantar pressure insole for estimating the three-dimensional ground reaction force (GRF) as well as the frictional torque (TF) during walking. Eleven subjects, six healthy and five patients with ankle disease participated in the study while wearing pressure insoles during several walking trials on a force-plate. The plantar pressure distribution was analyzed and 10 principal components of 24 regional pressure values with the stance time percentage (STP) were considered for GRF and TF estimation. Both linear and non-linear approximators were used for estimating the GRF and TF based on two learning strategies using intra-subject and inter-subjects data. The RMS error and the correlation coefficient between the approximators and the actual patterns obtained from force-plate were calculated. Our results showed better performance for non-linear approximation especially when the STP was considered as input. The least errors were observed for vertical force (4%) and anterior–posterior force (7.3%), while the medial-lateral force (11.3%) and frictional torque (14.7%) had higher errors. The result obtained for the patients showed higher error; nevertheless, when the data of the same patient were used for learning, the results were improved and in general slight differences with healthy subjects were observed. In conclusion, this study showed that ambulatory pressure insole with data normalization, an optimal choice of inputs and a well-trained nonlinear mapping function can estimate efficiently the three-dimensional ground reaction force and frictional torque in consecutive gait cycle without requiring a force-plate.

Gillette Gait Index in adults - Corrected Proof

Armel Cretual, Kristell Bervet, Laurent Ballaz — 2010-06-24

Abstract: Gillette Gait Index (GGI) is a very useful tool to assess gait abnormalities. However, it seems that it has only been validated in children with cerebral palsy. Nevertheless, the parameters used to compute GGI are not specific to children population. Our aim is to demonstrate that GGI could also be used to evaluate adults gait abnormalities. 44 adults (25 healthy and 19 pathological) participated to this study. Pathological subjects had a diagnosis of central nervous system pathology (6 with spinal cord injury and 13 with brain injury). We first, compared the kinematic parameter values of our healthy adult group to healthy children group in previous studies. It appears that those parameters’ variability is a bit lower in adults, which makes the GGI more sensitive. Moreover, the GGI in adults is too much dependent on one parameter among the 16 proposed by Schutte et al. (2000), the “Time of Peak Flexion”. Finally, the Edinburgh Visual Gait Score (EVGS) is correlated to GGI in children. To emphasize the relevance of GGI in adults, we have evaluated the correlation between EVGS and GGI in our pathological group. Those two parameters are indeed highly correlated. All these results allow us to conclude that the GGI computed with the 15 remaining parameters is a useful tool to assess gait abnormalities in adults.

Energy expenditure of stroke patients during postural control tasks - Corrected Proof

2010-06-23

Abstract: Two common impairments in patients after stroke are loss of balance control and fatigue. We propose that both could be inter-related. The purpose of this study was to investigate the metabolic energy demand for balance control in patients after stroke during upright standing. Ten stroke patients and 12 able-bodied controls performed four 5-min upright standing tasks on a force plate; unperturbed (SU), blindfolded (SUB), on foam surface (SUF) and with feet parallel against each other (SUP). Metabolic energy expenditure, posturography measures and muscle activity (EMG) of lower leg muscles were measured. Patients required on average 125% (33Jkg−1s−1) more metabolic energy for upright standing under the various conditions than controls. In addition, balance manipulation significantly (p<0.05) affected energy expenditure (21% higher in SUB, 52% in SUF, 40% in SUP compared to SU). Although the increase in energy expenditure was on average twice as high in patients than controls no significant group by condition interaction effect was found. Overall correlations between posturography measures, EMG and energy expenditure (r=0.33–0.60) were significant (p<0.001). We conclude that impaired balance control puts an extra demand on the energy expenditure during motor activities in stroke patients. This should be considered when prescribing interventions aimed at reducing physiological strain.

Temporal–spatial parameters of the upper limb during a Reach & Grasp Cycle for children - Corrected Proof

Erin E. Butler, Amy L. Ladd, Lauren E. LaMont, Jessica Rose — 2010-06-17

Abstract: The objective of this study was to characterize normal temporal–spatial patterns during the Reach & Grasp Cycle and to identify upper limb motor deficits in children with cerebral palsy (CP). The Reach & Grasp Cycle encompasses six sequential tasks: reach, grasp cylinder, transport to self (T1), transport back to table (T2), release cylinder, and return to initial position. Three-dimensional motion data were recorded from 25 typically developing children (11 males, 14 females; ages 5–18 years) and 12 children with hemiplegic CP (2 males, 10 females; ages 5–17 years). Within-day and between-day coefficients of variation for the control group ranged from 0 to 0.19, indicating good repeatability of all parameters. The mean duration of the Cycle for children with CP was nearly twice as long as controls, 9.5±4.3s versus 5.1±1.2s (U=37.0, P=.002), partly due to prolonged grasp and release durations. Peak hand velocity occurred at approximately 40% of each phase and was greater during the transport (T1, T2) than non-transport phases (reach, return) in controls (P<.001). Index of curvature was lower during transport versus non-transport phases for all children. Children with CP demonstrated an increased index of curvature during reach (U=46.0, P=.0074) and an increased total number of movement units (U=16.5, P<.0001) compared to controls, indicating less efficient and less smooth movements. Total duration of the Reach & Grasp Cycle (rho=.957, P<.0001), index of curvature during reach and T1 (rho=.873, P=.0002 and rho=.778, P=.0028), and total number of movement units (rho=.907, P<.0001) correlated strongly with MACS score. The consistent normative data and the substantial differences between children with CP and controls reflect utility of the Reach & Grasp Cycle for quantitative evaluation of upper limb motor deficits.