Biomechanics Commons^™

Stride-To-Stride Variability Is Altered During Backward Walking In Anterior Cruciate Ligament Deficient Patients, Franceska Zampeli, Constantina Moraiti Moraiti, Sofia Xergia, Vasilios Tsiaras, Nikolaos Stergiou, Anastasios D. Georgoulis

Journal Articles

Background: Recently backward walking is used by physical therapists to strengthen the hamstring muscles and thus improve the function of the knee joint of anterior cruciate ligament deficient patients. The aim of this study was to examine the stride-to-stride variability of anterior cruciate ligament deficient patients during backward walking. The variation of how a motor behavior emerges in time is best captured by tools derived from nonlinear dynamics, for which the temporal sequence in a series of values is the facet of interest.

Methods: Fifteen patients with unilateral anterior cruciate ligament deficiency and eleven healthy controls walked backwards …

The Effect Of Music On Robot-Assisted Laparoscopic Surgical Performance, Ka-Chun Siu, I. H. Suh, Mukul Mukherjee, D. Oleynikov, Nikolaos Stergiou

Journal Articles

Music is often played in the operating room to increase the surgeon’s concentration and to mask noise. It could have a beneficial effect on surgical performance. Ten participants with limited experience with the da Vinci robotic surgical system were recruited to perform two surgical tasks: suture tying and mesh alignment when classical, jazz, hip-hop, and Jamaican music were presented. Kinematics of the instrument tips of the surgical robot and surface electromyography of the subjects were recorded. Results revealed that a significant music effect was found for both tasks with decreased time to task completion (P = .005) and total …

A Comparison Of Interventions For Children With Cerebral Palsy To Improve Sitting Postural Control: A Clinical Trial, Regina T. Harbourne, Sandra L. Willett, Anastasia Kyvelidou, Joan E. Deffeyes, Nikolaos Stergiou

Journal Articles

Background The ability to sit independently is fundamental for function but delayed in infants with cerebral palsy (CP). Studies of interventions directed specifically toward sitting in infants with CP have not been reported.

Objective The purpose of this study was to compare 2 interventions for improving sitting postural control in infants with CP.

Design For this randomized longitudinal study, infants under 2 years of age and at risk for CP were recruited for intervention directed toward sitting independence.

Setting The intervention was conducted at home or at an outpatient facility.

Patients and Intervention Fifteen infants with typical development (mean age …

Acl Reconstructed Patients With A Bptb Graft Present An Impaired Vastus Lateralis Neuromuscular Response During High Intensity Running, Kostas Patras, Giorgos Ziogas, Stavros Ristanis, Elias Tsepis, Nikolaos Stergiou, Anastasios D. Georgoulis

Journal Articles

The purpose of the present study was to investigate whether the electromyographic response of the vastus lateralis (VL) muscle in the anterior cruciate ligament (ACL) reconstructed leg is similar to that of the intact contralateral leg and healthy controls, during moderate and high intensity running. Fourteen bone–patellar tendon–bone (BPTB) ACL reconstructed amateur soccer players and fourteen healthy control amateur soccer players volunteered to participate in the study. Electromyographic (EMG) traces from the vastus lateralis (VL) muscle were collected bilaterally, as athletes ran on a treadmill for 10 min on separate occasions, at moderate and high intensity. The dependent variable examined …

Gait Variability Patterns Are Altered In Healthy Young Individuals During The Acute Reperfusion Phase Of Ischemia-Reperfusion, Sara A. Myers, Nikolaos Stergiou, Iraklis Pipinos, Jason Johanning

Journal Articles

Background

The role of ischemia reperfusion contributing to functional impairment in lower extremity peripheral arterial disease (PAD) patients has not previously been elucidated. The evaluation of gait variability patterns has proven useful in many pathologic populations. Therefore, the purpose of this study is to isolate and determine the specific effect of the acute reperfusion phase of ischemia-reperfusion on gait variability in young individuals with no vascular disease.

Materials and Methods

Thirty healthy young individuals walked on a treadmill during baseline and the acute reperfusion phase of ischemia-reperfusion conditions while lower extremity joint kinematics were captured. Stride to stride variability was …

Severity And Characteristics Of Developmental Delay Can Be Assessed Using Variability Measures Of Sitting Posture, Anastasia Kyvelidou, Regina T. Harbourne, Nikolaos Stergiou

Journal Articles

Purpose: We sought to identify measures of variability from sitting postural sway that are significantly different among infants who were developing typically, those who were developmentally delayed or hypotonic, and those who later on had a diagnosis of spastic or athetoid cerebral palsy.

Methods: Sixty-five infants were evaluated when they were just developing the ability to sit upright by assessing center of pressure (COP) data, using measures of both amount and temporal organization of COP variability.

Results: The results indicated that measures of variability of COP could discriminate between infants with developmental delay and infants with cerebral palsy and add …

Reliability Of Center Of Pressure Measures For Assessing The Development Of Sitting Postural Control In Infants With Or At Risk Of Cerebral Palsy, Anastasia Kyvelidou, Regina T. Harbourne, Valerie K. Shostrom, Nikolaos Stergiou

Journal Articles

Objective

To establish the test-retest reliability of linear and nonlinear measures, including intra- and intersession reliability, when used to analyze the center of pressure (COP) time series during the development of infant sitting postural control in infants with or at risk for cerebral palsy (CP).

Design

Longitudinal study.

Setting

University hospital laboratory.

Participants

Infants with or at risk for CP (N=18; mean age ± SD at entry into the study, 13.7±3.6mo).

Interventions

Not applicable.

Main Outcome Measures

Infant sitting COP data were recorded for 3 trials at each session (2 sessions for each month within 1 week) for 4 consecutive …

Response To Chastin Et Al.: Analysis Of Nonlinear Patterns Of Activity, James T. Cavanaugh, Nicholas Stergiou

Journal Articles

We appreciate the thoughtful commentary by Chastin and colleagues regarding our recent article entitled “Nonlinear Analysis of Ambulatory Activity Patterns in Community-dwelling Older Adults.” (1) We fully agree with their observation that the application of nonlinear analytical tools to accelerometry data is an emerging area of research that shows potential for illuminating the complex nature of physical activity profiles. We also welcome the opportunity to discuss their concerns regarding (a) our application of detrended fluctuation analysis (DFA), entropy rate, and approximate entropy to natural activity data and (b) our narrow focus on stepping activity.

Treatment With Pharmacological Agents In Peripheral Arterial Disease Patients Does Not Result In Biomechanical Gait Changes, Jessie M. Huisinga, Iraklis Pipinos, Nikolaos Stergiou, Jason Johanning

Journal Articles

Pharmacological treatment has been used to alleviate the claudication symptoms and improve walking performance in peripheral arterial disease (PAD) patients. However, the effects of claudication treatments on gait mechanics have not been objectively indentified with biomechanical techniques. For this study, 20 PAD patients were assigned to take either pentoxifylline (n = 11) or cilostazol (n = 9), the two FDA-approved pharmacological therapies used to treat intermittent claudication symptoms. All patients completed a gait evaluation protocol that involved the acquisition of kinematic and kinetic gait data before use of the medication and after 12 weeks of treatment. Results showed that treatment …

Head And Shoulder Posture Affect Scapular Mechanics And Muscle Activity In Overhead Tasks, Charles A. Thigpen, Darin A. Padua, Lori A. Michener, Kevin M. Guskiewicz, Carol Guiliani, Jay D. Keener, Nikolaos Stergiou

Journal Articles

Forward head and rounded shoulder posture (FHRSP) is theorized to contribute to alterations in scapular kinematics and muscle activity leading to the development of shoulder pain. However, reported differences in scapular kinematics and muscle activity in those with forward head and rounded shoulder posture are confounded by the presence of shoulder pain. Therefore, the purpose of this study was to compare scapular kinematics and muscle activity in individuals free from shoulder pain, with and without FHRSP. Eighty volunteers were classified as having FHRSP or ideal posture. Scapular kinematics were collected concurrently with muscle activity from the upper and lower trapezius …

Abnormal Joint Powers Before And After The Onset Of Claudication Symptoms, Panagiotis Koutakis, Jason Johanning, Sara A. Myers, Nikolaos Stergiou, G. Matthew Longo, Iraklis Pipinos

Journal Articles

Objective: Claudication is the most common manifestation of peripheral arterial disease, producing significant ambulatory compromise. Our study evaluated patients with bilateral lower limb claudication and characterized their gait abnormality based on advanced biomechanical analysis using joint torques and powers.

Methods: Twenty patients with bilateral claudication (10 with isolated aortoiliac disease and 10 with combined aortoiliac and femoropopliteal disease) and 16 matched controls ambulated on a walkway while 3-dimensional biomechanical data were collected. Patients walked before and after onset of claudication pain. Joint torques and powers at early, mid, and late stance for the hip, knee, and ankle joints were calculated …

The Effect Of Virtual Reality On Gait Variability, Dimitrios Kastavelis, Mukul Mukherjee, Leslie M. Decker, Nikolaos Stergiou

Journal Articles

Optic Flow (OF) plays an important role in human locomotion and manipulation of OF characteristics can cause changes in locomotion patterns. The purpose of the study was to investigate the effect of the velocity of optic flow on the amount and structure of gait variability. Each subject underwent four conditions of treadmill walking at their self-selected pace. In three conditions the subjects walked in an endless virtual corridor, while a fourth control condition was also included. The three virtual conditions differed in the speed of the optic flow displayed as follows – same speed (OFn), faster (OFf), and slower (OFs) …

The Effect Of Pharmacological Treatment On Gait Biomechanics In Peripheral Arterial Disease Patients, Jessie M. Huisinga, Iraklis Pipinos, Jason Johanning, Nikolaos Stergiou

Journal Articles

Background: Pharmacological treatment has been advocated as a first line therapy for Peripheral Arterial Disease (PAD) patients suffering from intermittent claudication. Previous studies document the ability of pharmacological treatment to increase walking distances. However, the effect of pharmacological treatment on gait biomechanics in PAD patients has not been objectively evaluated as is common with other gait abnormalities. Methods: Sixteen patients were prescribed an FDA approved drug (Pentoxifylline or Cilostazol) for the treatment of symptomatic PAD. Patients underwent baseline gait testing prior to medication use which consisted of acquisition of ground reaction forces and kinematics while walking in a pain free …

Effects Of Varying Amounts Of Pronation On The Mediolateral Ground Reaction Forces During Barefoot Versus Shod Running, Joanna B. Morley, Leslie M. Decker, Tracy Dierks, Daniel Blanke, Jeffrey French, Nikolaos Stergiou

Journal Articles

Despite extensive research on running mechanics, there is still a knowledge gap with respect to the degree of relationship between mediolateral ground reaction forces (ML-GRF) and foot pronation. Our goal was to investigate whether differences exist in ML-GRF among runners that exhibit different degrees of pronation. Seventeen male and 13 female recreational runners ran with and without shoes while ML-GRF and frontal kinematics were collected simultaneously. Subjects were divided into groups based upon their peak eversion (low pronation, middle pronation, high pronation). Discrete parameters from the ML-GRF were peak forces, respective times of occurrence, and impulses. No significant differences were …

Impact Of Resistance Training On Balance And Gait In Multiple Sclerosis, Mary Filipi, M. Patricia Leuschen, Jessie M. Huisinga, Lorene Schmaderer, Jeanna Vogel, Daryl Kucera, Nikolaos Stergiou

Journal Articles

Multiple sclerosis (MS) is an incurable neurodegenerative disease whose symptoms are only partially relieved by pharmaceutical intervention. Disability due to this disease process can impede activities of daily living and decrease quality of life, both for MS patients and for their care partners and families. A nonrandomized, nonblinded prospective cohort study of 45 patients with MS was undertaken to investigate the impact of an exercise program emphasizing resistance training on balance and gait. This article presents data for the first 33 participants to complete the study protocol. The exercise program consisted of twice-weekly 50-minute sessions for 6 months. At 3 …

A Remote Markerless Human Gait Tracking For E-Healthcare Based On Content-Aware Wireless Multimedia Communications, Haiyan Luo, Song Ci, Dalei Wu, Nikolaos Stergiou, Ka-Chun Siu

Journal Articles

Remote human motion tracking and gait analysis over wireless networks can be used for various e-healthcare systems for fast medical prognosis and diagnosis. However, most existing gait tracking systems rely on expensive equipment and take lengthy processes to collect gait data in a dedicated biomechanical environment, limiting their accessibility to small clinics located in remote areas. In this work we propose a new accurate and cost-effective e­ healthcare system for fast human gait tracking over wireless networks, where gait data can be collected by using advanced video content analysis techniques with low-cost cameras in a general clinic environment. Furthermore, based …

Lyapunov Exponent And Surrogation Analysis Of Patterns Of Variability: Profiles In New Walkers With And Without Down Syndrome, Beth A. Smith, Nikolaos Stergiou, Beverly D. Ulrich

Journal Articles

In previous studies we found that preadolescents with Down syndrome (DS) produce higher amounts of variability (Smith et al., 2007) and larger Lyapunov exponent (LyE) values (indicating more instability) during walking than their peers with typical development (TD) (Buzzi & Ulrich, 2004). Here we use nonlinear methods to examine the patterns that characterize gait variability as it emerges, in toddlers with TD and with DS, rather than after years of practice. We calculated Lyapunov exponent (LyE) values to assess stability of leg trajectories. We also tested the use of 3 algorithms for surrogation analysis to investigate mathematical periodicity of toddlers’ …

Joint Torques And Powers Are Reduced During Ambulation For Both Limbs In Patients With Unilateral Claudication, Panagiotis Koutakis, Iraklis Pipinos, Sara A. Myers, Nikolaos Stergiou, Thomas G. Lynch, Jason Johanning

Journal Articles

Objectives: Symptomatic peripheral arterial disease (PAD) results in significant gait impairment. In an attempt to fully delineate and quantify these gait alterations, we analyzed joint kinematics, torques (rotational forces), and powers (rotational forces times angular velocity) in patients with PAD with unilateral claudication for both the affected and nonaffected legs.

Methods: Twelve patients with unilateral PAD (age, 61.69 ± 10.53 years, ankle-brachial index [ABI]: affected limb 0.59 ± 0.25; nonaffected limb 0.93 ± 0.12) and 10 healthy controls (age, 67.23 ± 12.67 years, ABI >1.0 all subjects) walked over a force platform to acquire gait kinetics, while joint kinematics were …

Nonlinear Analysis Of Ambulatory Activity Patterns In Community-Dwelling Older Adults, James T. Cavanaugh, Naomi Kochi, Nikolaos Stergiou

Journal Articles

Background The natural ambulatory activity patterns of older adults are not well understood. User-worn monitors illuminate patterns of ambulatory activity and generate data suitable for analysis using measures derived from nonlinear dynamics.

MethodsAmbulatory activity data were collected continuously from 157 community-dwelling older adults for 2 weeks. Participants were separated post hoc into groups based on the mean number of steps per day: highly active (steps ≥ 10,000), moderately active (5,000 ≤ steps < 10,000 steps), and inactive (steps

Results All groups displayed patterns of fluctuating step count values containing complex temporal structure. DFA, ER, and ApEn parameter values increased monotonically and significantly with increasing activity …

Complexity And Human Gait, Leslie M. Decker, Fabien Cignetti, Nikolaos Stergiou

Journal Articles

Recently, the complexity of the human gait has become a topic of major interest within the field of human movement sciences. Indeed, while the complex fluctuations of the gait patterns were, for a long time, considered as resulting from random processes, the development of new techniques of analysis, so-called nonlinear techniques, has open new vistas for the understanding of such fluctuations. In particular, by connecting the notion of complexity to the one of chaos, new insights about gait adaptability, unhealthy states in gait and neural control of locomotion were provided. Through methods of evaluation of the complexity, experimental results obtained …

Anterior Cruciate Ligament Reconstruction Results In Alterations In Gait Variability, Constantina O. Moraiti, Nikolaos Stergiou, Haris S. Vasiliadis, Eustathios Motsis, Anastasios D. Georgoulis

Journal Articles

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 …

Attractor Divergence As A Metric For Assessing Walking Balance, Max J. Kurz, Katerina Markopoulou, Nikolaos Stergiou

Journal Articles

: Individuals with Parkinson's disease and the aged have a high prevalence of falls. Since an increase in the number of falls is associated with physical and psychological harm, it is prudent that biomechanical metrics be established that will accurately assess an individual's walking balance. In this investigation, we initially used a simple bipedal walking computer model to theoretically establish the relationship between attractor divergence and walking balance. The Lyapunov exponent was used to quantify the amount of divergence present in the walking attractor. Simulations from our model indicated that attractors that have a greater amount of divergence are more …

The Impact Of Environmental Noise On Robot-Assisted Laparoscopic Surgical Performance, Ka-Chun Siu, I. H. Suh, Mukul Mukherjee, D. Oleynikov, Nikolaos Stergiou

Journal Articles

Background. An operating room is a noisy environment. How noise affects performance during robotic surgery remains unknown. We investigated whether noise during training with the da Vinci surgical robot (Intuitive Surgical, Inc., Sunnyvale, CA) would affect the performance of simple operative tasks by the surgeon.

Methods. Twelve medical students performed 3 inanimate operative tasks (bimanual carrying, suture tying, and mesh alignment) on the da Vinci Surgical System with or without the presence of noise. Prerecorded noise from an actual operating room was used. The kinematics of the robotic surgical instrument tips and the muscle activation patterns of the subjects were …

Variability Of Lower Extremity Joint Kinematics During Backward Walking In A Virtual Environment, Dimitrios Kastavelis, Mukul Mukherjee, Leslie M. Decker, Nikolaos Stergiou

Journal Articles

Backward walking (BW) shows significant differences with forward walking (FW) and these differences are potentially useful in rehabilitation. However the lack of visual cues makes BW risky. The purpose of this study was to investigate the effect of visual cues provided by a virtual environment on FW and BW on gait variability. Each subject underwent four conditions of treadmill walking at self-selected pace. The subjects walked backwards in three conditions and forwards in the fourth condition. A virtual corridor was displayed to the subjects in the FW condition (forward optic flow) and two of the backward conditions (forward and backward …