Gait & Posture

Contents List

2010-06-01

Editorial Board

2010-06-01

Gait adaptations in response to perturbations in adults with Down syndrome

Beth A. Smith, James A. Ashton-Miller, Beverly D. Ulrich — 2010-05-10

Abstract: Objectives: Ligamentous laxity, hypotonia and physiologic changes associated with aging lead to gait adaptations to increase control during comfortable unperturbed walking in adults with Down syndrome (DS). These changes appear at earlier ages than changes associated with aging in adults with typical development (TD) . Here we describe gait adaptation and stability when gait is perturbed in relatively older adults with DS compared to their peers with TD.Participants: A volunteer sample of 14 adults with DS and 14 adults with TD, all 35–65 years of age, participated.Methods: We used 3D motion analysis to capture walking patterns at self-selected pace and in seven environmentally relevant perturbation conditions. We tested for group differences in gait parameters and amount of variability by condition: specifically percent stance, step width and stride length, velocity and frequency. To quantify overall change in gait parameters and variability from baseline to each condition, we created summative parameters of the overall percent change from baseline to each condition for each dependent variable.Results: Adults with DS and TD made small but complex adjustments in gait parameters and variability in response to perturbations.Conclusions: Overall adults in both groups maintained group differences in gait patterns while adapting well to anticipated perturbations.

On the role of knee joint in balance control and postural strategies: Effects of total knee replacement in elderly subjects with knee osteoarthritis

2010-05-10

Abstract: This study aimed to evaluate the role of the knee joint in the neurosensory organization of balance control and the generation of postural sensorimotor strategies. Ten patients, aged over 60 years and having undergone unilateral total knee replacement (TKR) for osteoarthritis, and 20 controls were submitted to static and dynamic posturographic tests and to a sensory organization test (SOT) aiming at evaluating postural control in quiet stance and during movement. The patients were submitted to these evaluations after the disappearance of pain (TKR1) and at the end of a 6-week rehabilitation program (TKR2). Balance control being greatly improved at TKR2 compared to TKR1, the patients attain a quality of postural regulation similar to that of the controls; some postural abnormalities did however persist for the static test. Moreover, SOT values at TKR2 close to those of the controls highlighted an improvement in motor response, better management in altered proprioceptive information situations, and greater use of the ankle to control balance. This model of intervention on the knee joint, namely knee replacement due to osteoarthritis, has shown that gradual functional sensorimotor restoration after TKR, due to intrasensory proprioceptive compensation either at knee, or at other joint levels (hip/ankle), improves dynamic balance control. This reacquisition allows the knee joint to recover its corrective compensatory role in postural regulation allowing, through neuroplasticity, the modification of muscular activation sequences and, thus, the implementation of anticipatory sensorimotor strategies.

Attenuation of the evoked responses with repeated exposure to proprioceptive disturbances is muscle specific

Sébastien Caudron, Lucas Langlois, Vincent Nougier, Michel Guerraz — 2010-05-05

Abstract: In response to repetitive proprioceptive disturbances (vibration) applied to postural muscles, the evoked response has been shown to decrease in amplitude within the first few trials. The present experiment investigated whether this attenuation of the response to vibration stimulation (90Hz, 5s) was muscle specific or would be transferred to the antagonist muscles. Sixteen participants stood upright with eyes closed. One half of the participants practiced 15 tibialis vibrations followed by 15 calf vibrations (TIB-CALF order), while the other half practiced the opposite order (CALF-TIB order). Antero-posterior trunk displacements were measured at the level of C7 and centre of foot pressure (COP). EMG activity of the tibialis anterior (TA) and gastrocnemius lateralis (GL) was also measured. Results showed that evoked postural responses as well as EMG activity decreased with practice when vibration was applied to either calf or tibialis muscles. However, such attenuation of the response appeared muscle specific since it did not generalise when the same vibration stimulus was later applied onto the antagonist muscles.

Anterior cruciate ligament reconstruction results in alterations in gait variability

2010-06-30

Abstract: Introduction: The temporal structure of gait variability has shown that healthy human gait exhibits long-range correlations and deterministic properties which allow the neuromuscular system to be flexible and adaptable to stresses. Pathology results in deterioration of these properties. We examined structure of gait variability after ACL reconstruction with either BPTB or quadrupled ST/G tendon autografts.Methods: Six patients with BPTB reconstruction, six with ST/G reconstruction and six healthy controls walked on a treadmill at their self-selected pace. Two minutes of continuous kinematic data were recorded with a 6-camera optoelectronic system. The nonlinear measure of the largest Lyapunov Exponent (LyE) was estimated from the knee flexion-extension time series from 100 continuous walking strides to assess the structure of gait variability.Results: The reconstructed limbs in both reconstructed groups exhibited significantly larger LyE values than the control limbs (p<0.05), even though clinical outcomes indicated complete restoration. No significant differences were found between the two autografts. In addition, the intact contralateral leg produced significant higher LyE values as compared with the ACL-reconstructed leg in both groups. No interaction was found.Discussion: The larger LyE values indicate that the reconstructed knees of both reconstructed groups exhibit more divergence in the movement trajectories during gait. The larger Lye values found in the intact leg in both reconstructed groups could be interpreted as a compensatory mechanism. However, the increased divergence found in both limbs may present an alternative explanation for the impaired neuromuscular performance and increased susceptibility to future pathology, which is supported by the increased amount of osteoarthritis found in ACL-reconstructed patients.

The effect of evenly distributed load carrying on lower body gait dynamics for normal weight and overweight subjects

Benjamin Smith, Michael Roan, Minhyung Lee — 2010-05-17

Abstract: The carrying of extra weight can cause significant injuries. This extra weight can be in the form of an external load carried by an individual or excessive body weight carried by an overweight individual. This study attempts to define the differences in lower body gait patterns caused by either external load carriage, excessive body weight, or a combination of both. Twenty-three subjects generated 115 trials of motion capture data for each loading condition. Path lengths of the phase portrait and the ranges of joint motions (hip, knee and ankle) were used to quantify subgroup differences. The study found significant gait differences due to external load carriage and excessive body weight. Within each class of normal weight and overweight subjects, differences were found in the hip and ankle path lengths when a subject carried an evenly distributed external load. This implies that these joints may be more prone to injury due to external load carriage.

Effective rocker shapes used by able-bodied persons for walking and fore-aft swaying: Implications for design of ankle–foot prostheses

Andrew H. Hansen, Charles C. Wang — 2010-05-17

Abstract: The use of rocker models to understand functional tasks of the human lower limb is attractive because of their simplicity. Recent studies have determined a consistent feature of able-bodied walking termed the roll-over shape (ROS), which is the effective rocker shape that the lower limb system conforms to between initial contact and contralateral initial contact during walking. However, it is unclear what effective rocker shapes are used for fore-aft swaying. A better understanding of these shapes could be used to develop improved prostheses for this task, perhaps improving balance and balance confidence, and reducing the occurrence of falling in lower limb prosthesis users. We measured effective rocker shapes used by 11 able-bodied persons during walking and fore-aft swaying. We hypothesized that the curvature of the swaying shapes would be smaller (radius larger) than that of the walking shapes, providing a more stable interface with the ground during swaying. The radius (measured as the inverse of the curvature of the shape) was found to be about 1/3 of the leg length for walking, but over two times the leg length for swaying. A model examining the effective ankle stiffness necessary to achieve these curvatures suggests that the stiffness of a biomimetic prosthetic ankle would need to be over three times higher for fore-aft swaying than for walking. These results suggest that two separate modes would be needed in an ankle–foot prosthesis to mimic the physiologic system for walking and swaying.

An exercise intervention to improve diabetic patients’ gait in a real-life environment

L. Allet, S. Armand, K. Aminian, Z. Pataky, A. Golay, R.A. de Bie, E.D. de Bruin — 2010-05-14

Abstract: Aims: Gait characteristics and balance are altered in diabetic individuals. Little is known about possible treatment strategies. This study evaluated the effect of a specific training program on diabetic patients’ gait.Methods: A randomized controlled trial (N=71) with an intervention (IG) (N=35), and control group (CG) (N=36). The intervention consisted of physiotherapeutic group training including gait and balance exercises with function-oriented strengthening. Controls received no treatment.Results: After intervention the IG increased their habitual walking speed by 0.149ms−1 (0.54kmh−1) on tarred terrain and by 0.169ms−1 (0.61kmh−1) on the cobblestones. This significant treatment effect (p<0.001) decreased slightly at the six-month follow-up, but remained significant (p<0.001). In a similar manner, significant improvement was observed for cadence, gait cycle time and stance time on both terrains. All outcomes except stance time on the tarred terrain remained significant at the six-month follow-up. No significant effect was observed for stride length and the coefficient of variation of gait cycle time (on either surface) at the corrected significance level of p<0.004. CG patients’ parameters all remained unchanged or progressively deteriorated compared to baseline values.Discussion: Cadence contributed 80%, whereas stride length only contributed 20% to the change of gait velocity. This may be due to the treatment or to diabetic patients’ potential to regulate their cadence and stride length.Conclusion: A specific training program can improve diabetic patients’ gait in a real life environment. A challenging environment highlights treatment effects on patients’ gait better than an evenly tarred surface.

Biomechanical analysis of ramp ambulation of transtibial amputees with an adaptive ankle foot system

Laetitia Fradet, Merkur Alimusaj, Frank Braatz, Sebastian I. Wolf — 2010-05-11

Abstract: The fixed neutral position of conventional prosthetic feet causes difficulties for transtibial amputees (TTAs) when walking on ramps. New microprocessor-controlled prosthetic ankles such as the Proprio-Foot® (Össur) aim to reduce these difficulties by modifying the prosthetic ankle angle according to the gait condition. The purpose of the present investigation was to assess the biomechanical effects of adaptation of the prosthetic ankle on ramp ambulation in TTAs. Sixteen TTAs and 16 controls underwent a conventional 3D gait analysis while walking up and down a ramp. TTAs walked with the prosthetic foot set to a neutral mode angle and set to the adapted mode. Norm distance, sagittal kinematics and kinetics were calculated for comparisons between TTAs and controls. During ramp ascent, the dorsiflexion brought about by the adapted prosthetic ankle reduced the increased knee extension noted on the TTAs’ involved side and the increased plantarflexion on their sound side. During ramp descent, the plantarflexion of the adapted mode increased the adaptation mechanisms observed in TTAs. These findings suggest that the adapted mode leads to more physiologic kinematics and kinetics in the lower limbs in TTAs during ramp ascent but not during ramp descent. However, in the adapted mode, patients reported feeling safer during ramp descent, thus indicating that there might be other safety related measures such as toe-clearance or coefficient of friction influencing this perception.

Effects of robot-driven gait orthosis treadmill training on the autonomic response in rehabilitation-responsive stroke and cervical spondylotic myelopathy patients

2010-06-01

Abstract: Body weight supported treadmill training (BWSTT) assisted with a robotic-driven gait orthosis is utilized in rehabilitation of individuals with lost motor skills. A typical rehabilitation session included: sitting, standing, suspension, robotic-assisted walking at 1.5 and 2.5km/h, respectively with 50% body weight support and recovery. While the effects of robotic-assisted BWSTT on motor performances were deeply studied, the influences on the cardiovascular control are still unknown.The aim of the study was to evaluate in stroke (ST) and cervical spondylotic myelopathy (CSM) patients: (1) the autonomic response during a traditional robotic-assisted BWSTT session of motor rehabilitation; (2) the effects of 30 daily sessions of BWSTT on cardiovascular regulation. The autonomic response was assessed through symbolic analysis of short-term heart rate variability in 11 pathologic subjects (5 ST and 6 CSM patients) whose motor skills were improved as a result of the rehabilitation therapy.Results showed variable individual responses to the rehabilitation session in ST patients at the beginning of the therapy. At the end of the rehabilitation process, the responses of ST patients were less variable and more similar to those previously observed in healthy subjects. CSM patients exhibited an exaggerated vagal response to the fastest walking phase during the first rehabilitative session. This abnormal response was limited after the last rehabilitative session.We conclude that robotic-assisted BWSTT is helpful in restoring cardiovascular control in rehabilitation-responsive ST patients and limiting vagal responses in rehabilitation-responsive CSM patients.

Knee kinetics during walking at different speeds in people who have undergone total knee replacement

Jodie A. McClelland, Kate E. Webster, Julian A. Feller, Hylton B. Menz — 2010-06-01

Abstract: Previous research suggests that most people who have undergone total knee replacement (TKR) walk with a sagittal knee moment profile and peak knee moments that are different from normal. However, most previous research has consisted of small samples of patients with prostheses that are no longer in use. The aim of this study was to compare the peak knee moments and patterns of the moment waveforms of walking at different speeds between a large cohort of TKR patients with the Genesis-II PS prosthesis (Smith and Nephew, Memphis, USA) and matched control participants. Forty patients 12months following TKR and 40 control participants were assessed during walking at self-selected comfortable and fast speeds using motion analysis. Individual sagittal plane knee moment graphs were assessed for the presence of a biphasic pattern. Peak sagittal and coronal plane knee moments were compared between groups using a univariate ANOVA with walking speed as a covariate. A biphasic moment pattern was present in 87% and 92% of TKR patients when walking at comfortable and fast speeds, respectively. The knee flexor (p<0.001 at both speeds), extensor (p=0.004 at comfortable speed and p<0.001 at fast speed) and adductor (p<0.001 at both speeds) moments were reduced in the TKR patients. The high proportion of TKR patients with biphasic moment patterns was unexpected, but suggests that modern prostheses can result in more normal outcomes. Nonetheless, the peak knee moments of patients were reduced compared to controls. Although these reductions may be beneficial to the survival of the prosthesis, these abnormalities may also indicate suboptimal functional outcome from TKR.

Effect of walking velocity on segment coordination during pre-planned turns in healthy older adults

Sakineh B. Akram, James S. Frank, Julia Fraser — 2010-06-03

Abstract: Background: Despite the prevalence of turning in daily activities and the challenges it poses to mobility-impaired individuals, far less is known about the multi-segmental control of turning than the control of straight walking. Gait slows with aging and neurological disorders such as Parkinson's disease and falls in these populations frequently occur when turning. Nevertheless, the influence of walking velocity on the complex inter-segmental coordination of the head, trunk and lower limbs during turning has not been examined. The purpose of this study was to examine the effect of walking velocity on the coordination of segment reorientation during turns embedded in locomotion in healthy older adults.Methods: Nineteen healthy older adults volunteered to participate. Participants made a 45° or 90° turn to their right while walking either at their natural self-selected speed or slower or faster than their natural speed. We quantified the timing and sequence of segments reorientation during the turns.Results: There was a top-down temporal sequence in initiation of segments reorientation during turning, i.e., head turned first, followed by shoulder, pelvis, and mediolateral foot displacement. Furthermore, results indicate that the top-down temporal sequence in segments reorientation during turning was a robust behavior which was not affected by the walking velocity or magnitude of the turn.Conclusions: Walking velocity does not affect segment coordination during pre-planned turns in healthy elderly. Therefore, we conclude that changes in coordination of segments reorientation during pre-planned turns in individuals with neurological disorders such as Parkinson's disease is not due to their slower gait.

Standing in an unstable shoe increases postural sway and muscle activity of selected smaller extrinsic foot muscles

Scott C. Landry, Benno M. Nigg, Karelia E. Tecante — 2010-05-24

Abstract: Inactivity or the under-utilization of lower limb muscles can lead to strength and functional deficits and potential injury. Traditional shoes with stability and support features can overprotect the foot and potentially contribute to the deterioration of the smaller extrinsic foot muscles. Healthy subjects (n=28) stood in an unstable MBT (Masai Barefoot Technology) shoe during their work day for a 6-week accommodation period. A two-way repeated measures ANOVA was used to determine (i) if unstable shoe wear increased electromyographic (EMG) activity of selected extrinsic foot muscles and increased postural sway compared to standing barefoot and in a stable control shoe and (ii) if postural sway and muscle activity across footwear conditions differed between a pre- and post-accommodation testing visit. Using an EMG circumferential linear array, it was shown that standing in the unstable shoe increased activity of the flexor digitorum longus, peroneal (PR) and anterior compartment (AC) muscles of the lower leg. No activity differences for the larger soleus (SOL) were identified between the stable and unstable shoe conditions. Postural sway was greater while standing in the unstable shoe compared to barefoot and the stable control shoe. These findings suggest that standing in the unstable MBT shoe effectively activates selected extrinsic foot muscles and could have implications for strengthening and conditioning these muscles. Postural sway while standing in the unstable MBT shoe also decreased over the 6-week accommodation period.

Effects of maximal oxygen uptake test and prolonged cycle ergometer exercise on the quiet standing control

Roger Gomes Tavares Mello, Liliam Fernandes de Oliveira, Jurandir Nadal — 2010-06-14

Abstract: This work aims at testing the influence of peripheral and central fatigue, after maximal oxygen uptake test (Test1) and prolonged (Test2) cycle ergometer exercises, respectively, on sway density curve (SDC) parameters of postural control. Sixteen healthy male subjects were submitted to stabilometric tests, before and after the exercises. The Test1 was started at 12.5W, with 12.5W/min increments and 50rpm cadence until exhaustion. From the respiratory gas exchange signals, the first ventilatory threshold was obtained by the v-slope method. After a minimum of 72h, the subjects performed the Test2 for 60min, at a power output corresponding to 70% of such threshold. Before and just after these exercises, a set of 10 stabilometric trials of 50s was performed, alternating the eyes open and closed conditions, intercalated by a 10s resting period. The resulting signals were used to obtain the SDC. The Test1 caused decrease of the mean of peaks duration in SDC (p<0.05), decreasing the stability level, with small changes in the rates of central nervous system (CNS) and muscular torque controls. Conversely, Test2 increased the mean of time intervals between peaks in SDC (p<0.05), thus decreasing the CNS commands rate with minor changes in the stability level. Visual privation had a greater effect on body sway than these exercises, which were applied to muscles that are not the main actuators in body sway control. Concluding, this study allowed discriminating the effects of exercise intensities on body sway control.

Gait compensations caused by foot deformity in cerebral palsy

Julie Stebbins, Marian Harrington, Nicky Thompson, Amy Zavatsky, Tim Theologis — 2010-06-03

Abstract: Cerebral palsy (CP) is a complex syndrome, with multiple interactions between joints and muscles. Abnormalities in movement patterns can be measured using motion capture techniques, however determining which abnormalities are primary, and which are secondary, is a difficult task. Deformity of the foot has anecdotally been reported to produce compensatory abnormalities in more proximal lower limb joints, as well as in the contralateral limb. However, the exact nature of these compensations is unclear. The aim of this paper was to provide clear and objective criteria for identifying compensatory mechanisms in children with spastic hemiplegic CP, in order to improve the prediction of the outcome of foot surgery, and to enhance treatment planning. Twelve children with CP were assessed using conventional gait analysis along with the Oxford Foot Model prior to and following surgery to correct foot deformity. Only those variables not directly influenced by foot surgery were assessed. Any that spontaneously corrected following foot surgery were identified as compensations. Pelvic rotation, internal rotation of the affected hip and external rotation of the non-affected hip tended to spontaneously correct. Increased hip flexion on the affected side, along with reduced hip extension on the non-affected side also appeared to be compensations. It is likely that forefoot supination occurs secondary to deviations of the hindfoot in the coronal plane. Abnormal activity in the tibialis anterior muscle may be consequent to tightness and overactivity of the plantarflexors. On the non-affected side, increased plantarflexion during stance also resolved following surgery to the affected side.

Repeatability and reproducibility of OSSCA, a functional approach for assessing the kinematics of the lower limb

2010-05-26

Abstract: Marker-based gait analysis of the lower limb that uses assumptions of generic anatomical morphology can be susceptible to errors, particularly in subjects with high levels of soft tissue coverage. We hypothesize that a functional approach for assessing skeletal kinematics, based on the application of techniques to reduce soft tissue artefact and functionally identify joint centres and axes, can more reliably (repeatably and reproducibly) assess the skeletal kinematics than a standard generic regression approach.Six healthy adults each performed 100 repetitions of a standardized motion, measured on four different days and by five different observers. Using OSSCA, a combination of functional approaches to reduce soft tissue artefact and identify joint centres and axes, the lengths of the femora and tibiae were determined to assess the inter-day and inter-observer reliability, and compared against a standard generic regression approach. The results indicate that the OSSCA was repeatable and reproducible (ICC lowest bound 0.87), but also provided an improvement over the regression approach (ICC lowest bound 0.69). Furthermore, the analysis of variance revealed a statistically significant variance for the factor “observers” (p<0.01; low-reproducibility) when using the regression approach for determining the femoral lengths.Here, this non-invasive, rapid and robust approach has been demonstrated to allow the repeatable and reproducible identification of skeletal landmarks, which is insensitive to marker placement and measurement session. The reliability of the OSSCA thus allows its application in clinical studies for reducing the uncertainty of approach-induced systematic errors.

Foot progression angle and medial loading in individuals with diabetes mellitus, peripheral neuropathy, and a foot ulcer

2010-05-31

Abstract: Foot progression angle (FPA) and duration of foot medial column loading during walking were studied in individuals with diabetes mellitus (DM), peripheral neuropathy (PN), and a forefoot ulcer (DMPN), and in age-matched control subjects. FPA was calculated from EMED-ST P-2 pressure maps as the angle formed between the longitudinal axis of the foot and the forward line of progression during walking. The medial loading duration was calculated as the amount of time the center of pressure line spent in the medial side of the foot pressure map. FPA was increased in the DMPN group, on the involved and uninvolved sides [15(9)° and 13(4)° respectively] compared the control group [9(4)°]. FPA and medial loading duration were significantly correlated in the DMPN group on the involved and uninvolved sides (r>0.54, p<0.036), but were not significantly correlated in the control group (r 0.82). This study provides evidence that FPA is an important biomechanical contributor to the pattern of foot loading in individuals with DM, PN, and a forefoot ulcer.

Gait and neuromuscular adaptations after using a feedback-based gait monitoring knee brace

Jody L. Riskowski — 2010-06-17

Abstract: Purpose: The purpose of this study was to evaluate the gait and neuromuscular effects of a feedback-based gait monitoring knee brace. The aim of this paper was to explore how training with this knee brace affected the gait pattern utilized, rate of loading (ROL), and proprioceptive acuity.Methods: Fifteen healthy women wore this knee brace that provided audible feedback on gait kinematics for a 30-min training period. We performed pre- and post-gait analyses and proprioceptive acuity assessments to determine gait learning and adaptation with this training.Results: Post-training significant changes were seen in the knee angle prior to and at initial contact and peak knee extensor, flexor, and adductor moments, which ultimately led to a reduced ROL experienced. Subjects also had improved proprioceptive acuity post-training.Interpretations: Our results indicate that using a feedback-based gait monitoring knee brace can change the gait pattern by increasing the knee flexion angle during the swing to stance transition. Though there was an approximate 25% decrease in the ROL experienced, there was also an increase in the knee adductor moment. Future long-term studies are needed to further explore the positive and negative effects of feedback-based gait monitoring knee brace on individuals with a compromised knee joint, such as those post-anterior cruciate ligament injury.

Body size and walking cadence affect lower extremity joint power in children's gait

Sarah P. Shultz, Andrew P. Hills, Michael R. Sitler, Howard J. Hillstrom — 2010-05-31

Abstract: Obese children move less and with greater difficulty than normal-weight counterparts but expend comparable energy. Increased metabolic costs have been attributed to poor biomechanics but few studies have investigated the influence of obesity on mechanical demands of gait. This study sought to assess three-dimensional lower extremity joint powers in two walking cadences in 28 obese and normal-weight children. 3D-motion analysis was conducted for five trials of barefoot walking at self-selected and 30% greater than self-selected cadences. Mechanical power was calculated at the hip, knee, and ankle in sagittal, frontal and transverse planes. Significant group differences were seen for all power phases in the sagittal plane, hip and knee power at weight acceptance and hip power at propulsion in the frontal plane, and knee power during mid-stance in the transverse plane. After adjusting for body weight, group differences existed in hip and knee power phases at weight acceptance in sagittal and frontal planes, respectively. Differences in cadence existed for all hip joint powers in the sagittal plane and frontal plane hip power at propulsion. Frontal plane knee power at weight acceptance and sagittal plane knee power at propulsion were significantly different between cadences. Larger joint powers in obese children contribute to difficulty performing locomotor tasks, potentially decreasing motivation to exercise.

Functional reaching discloses perceptive impairment in diplegic children with cerebral palsy

Adriano Ferrari, Luca Tersi, Alberto Ferrari, Alice Sghedoni, Lorenzo Chiari — 2010-06-04

Abstract: The currently accepted definition classifies Cerebral Palsy (CP) as a mere posture and movement disorder. Conversely, some authors have recently associated the presence of several motor dysfunctions exhibited by diplegic children with CP to an impairment in the perceptive system. The aim of the present study was to investigate the influence of the Perceptive Impairment (PI) on motor control and to appraise if the PI can be revealed by a reaching task.A functional reach and touch experiment was accomplished from sitting posture considering different directions and distances. Typically developing and diplegic children with CP were enrolled and, the latter, a priori divided in two subgroups considering a positive or negative diagnosis of PI. The reaching trials were quantified by means of centre of pressure analysis in terms of the overall quality of the task, and accuracy and effectiveness of postural adjustments and Anticipatory Postural Adjustments (APAs).The three groups showed statistically significant differences in terms of percentage of touched target, and of time spent and maximum distance covered to reach the target. In particular, PI caused a major difficulty in accomplishing the reaching tasks, thus a lower autonomy level in action. Overall, the PI strongly affected the anticipatory control system. Children with PI, rarely recruited APAs, each of which was characterized by small amplitude and inaccuracy in direction. The lack of effective APAs indicated how PI strongly influenced the motor control strategy.The present study demonstrates that the PI is a primary syndrome responsible for the long-term prognosis beside the motor and the postural disorders in CP.

Influence of thigh muscle strength and balance on hop length in one-legged hopping in children aged 7–12 years

Anne Therese Tveter, Inger Holm — 2010-06-03

Abstract: Background: Lower extremity muscular strength and balance are essential components in many motor performance skills. One-legged hopping is considered to be the most advanced jumping skill, because it requires greater muscle strength and better balance than other jumping skills. To what degree muscle strength and balance have significant influence on hop length in children is, however, unknown.Objective: The purpose of the present study was to identify predictive factors for hop length in one-legged hopping. The main hypothesis was that both muscle strength of the thigh (quadriceps and hamstrings) and balance would be significant predictors in healthy children 7–12 years of age.Method: 341 girls and boys were included in the study. Hopping data was collected using the GAITRite system®, muscle strength was tested isokinetically by a Cybex 6000 and one leg static balance was measured by the KAT 2000 system.Results: Hop length and thigh muscle strength showed increased values from one age group to the next from 7 to 12 years of age, while static balance only showed minor fluctuation. Multiple regression analysis showed that thigh strength, static balance, age and gender all together explained 53.4% of the variance in hop length. Age, quadriceps strength and hamstrings strength made the largest contributions with Beta 0.32, p<0.001, Beta 0.26, p=0.001 and Beta 0.18, p=0.003, respectively. Static balance and gender did not contribute significantly.Conclusion: Of the measurements investigated in this study, age and thigh muscle strength are the strongest predictors for hop length in one-legged hopping skills in children.

Sagittal and frontal plane joint mechanics throughout the stance phase of walking in adolescents who are obese

A.G. McMillan, A.M.E. Pulver, D.N. Collier, D.S.B. Williams — 2010-06-23

Abstract: The incidence of obesity has increased dramatically in children and adolescents, and with this comes health risks typically associated with adult obesity. Among those health consequences are musculoskeletal damage and pain. Previous studies have demonstrated inconsistent effects of increased body mass on movement patterns in adults and children who are obese. The purpose of this study was to investigate frontal and sagittal plane mechanics during walking in adolescents who were obese. Adolescents (12–17 years) who were obese were recruited from a weight management program, and healthy weight peers (matched for age, race and gender) were recruited from the community. Three-dimensional motion analysis of the lower extremities was performed during walking. Analysis of kinematic and kinetic data from 36 adolescents who were obese and healthy weight revealed significant differences in mechanics at all lower extremity joints in both sagittal and frontal planes. Subjects who were obese seemed to use movement strategies that minimized joint moments, especially at the hip and knee during walking. The lower extremity mechanics during walking in the subjects who were obese raise concerns about maintenance of structural integrity of the lower extremity joints over time, given the repeated high stresses across the joints even with walking. Neither the long term consequences of these atypical movement patterns, nor the ability to alter these patterns through therapeutic activities or weight loss has been investigated in adolescents who are obese.

Lower limb biomechanics during gait do not return to normal following total hip arthroplasty

Mélanie L. Beaulieu, Mario Lamontagne, Paul E. Beaulé — 2010-06-14

Abstract: Although total hip arthroplasty (THA) is known to be a successful surgical procedure to alleviate hip pain and to improve health-related quality of life, these outcome measures in THA patients do not reach those of the general population. As a result, several investigators have assessed THA patients’ gait mechanics, but most of them have ignored adjacent joints, as well as the effect that THA may have on the non-operated limb. The purpose of this investigation was to determine the effect of THA on the pelvis, hip, knee and ankle joint kinematics, as well as the hip, knee and ankle kinetics of both the operated and non-operated limbs during walking. These data were recorded for 20 patients having undergone unilateral THA and 20 healthy, matched control participants. Results revealed that the gait mechanics of THA patients did not return to normal 10.6 months, on average (±2.6 mo), following surgery. THA patients walked with lower operated-hip abduction moments, sagittal-plane range of motion, as well as lower generated and absorbed power, that may be consequential to pain-avoidance strategies adopted pre-operatively or to apprehensions associated with their new prosthesis. They also displayed various kinematic adaptations at the ankle joint of the operated limb and at the non-operated hip joint that may be leaving them at risk of developing other joint diseases. Further investigation is needed to confirm the reasons why THA patients’ gait mechanics do not return to normal following surgery to develop better surgical techniques and/or rehabilitation programs.

The effects of shoe fit on gait in community-dwelling older adults

2010-06-14

Abstract: Shoes have a beneficial function in physical performance, particularly for gait. The purpose of this study was to investigate the association of shoe fit with gait parameters in community-dwelling older people. The fit of habitual shoes (HS) was evaluated in healthy older subjects and subjects were classified into well-fit (n=48) and poorly-fit (n=37) groups. The sizes of their feet were measured using an optical laser scanning system to provide newly-fitted shoes (NFS). Gait experiments were performed while wearing HS and NFS, separately. Trunk linear accelerations were measured along the vertical, anteroposterior and mediolateral axes using a tri-axial accelerometer attached to the L3 spinous process. Measurements were sampled at 200-Hz during a 20-m gait task at a self-selected speed. After signal processing, the gait velocity, stride duration, stride length and gait regularity (Reg) were obtained. Among the poorly-fit group, 86% wore shoes that were too loose. Subjects wearing ill-fitting shoes had a tendency to walk slower, had shorter stride lengths and lower Reg in the vertical direction than those wearing well-fitting shoes. Whereas NFS increased the gait velocity, the stride length and the Reg in the vertical direction, the increases in subjects that previously wore ill-fitting HS was significantly greater than in subjects that originally wore well-fitting HS. In conclusion, our study indicates that a significant proportion of older adults wear ill-fitting shoes and that well-fitting shoes are important to improve gait performance.

A new method for synchronization of motion capture and plantar pressure data

Adam L. Miller — 2010-06-11

Abstract: A common plantar pressure analysis technique requires dividing the pressure distribution into regions based on key landmarks of the foot. Typically, this is done using visual inspection of the footprint and is subject to error when there is abnormal foot contact. A novel, robust method of synchronizing motion capture and plantar pressure data was created that allows for motion capture markers to be projected onto the plantar pressure mat for accurate subdivision of the foot. Validation studies showed that spatial synchronization of the plantar pressure and motion capture systems was determined to be accurate within 1 sensel.

Repeatability of a new protocol for gait analysis in adult subjects

2010-06-11

Abstract: The reliability of kinematic measurements has a top priority in gait analysis. The aim of the present work was to assess the inter-trial, inter-session and inter-examiner variability of an anatomical-based protocol by an established method. The gait of two young adult volunteers was analyzed by four examiners with different degrees of experience in three sessions 1 week apart. The data of five trials of level walking were collected and the rotations in the three anatomical planes of the pelvis, hip, knee and ankle were calculated. The mean value over the gait cycle of the standard deviation of these rotations was calculated for each of the 24 groups of five trials (inter-trial), the eight groups of five trials multiplied by three sessions (inter-session), and the two groups of five trials multiplied by three sessions multiplied by four examiners (inter-examiner). For each rotation, the inter-examiner variability was larger than the inter-session, and the latter larger than the inter-trial. The present ratio between inter-examiner and inter-trial variability was found to be smaller than that of the conventional protocol for each of the gait variables.

SIAMOC Sociey Announcements

2010-06-01