Biomechanics Commons^™

Medicine Meets Virtual Reality 15, James D. Westwood, Matthew J. Fieldler, Shing-Jye Chen, Timothy N. Judkins, D. Oleynikov, Nikolaos Stergiou

Faculty Books and Monographs

Chapter, Virtual Reality for Robotic Laparoscopic Surgical Training, co-authored by Nicholas Stergiou, UNO faculty member.

Our culture is obsessed with design. Sometimes designers can fuse utility and fantasy to make the mundane appear fresh—a cosmetic repackaging of the same old thing. Because of this, medicine—grounded in the unforgiving realities of the scientific method and peer review, and of flesh, blood, and pain—can sometimes confuse “design” with mere “prettifying.” Design solves real problems, however. This collection of papers underwrites the importance of design for the MMVR community, within three different environments: in vivo, in vitro and in silico. in vivo: we …

Tibial Rotation Is Not Restored After Acl Reconstruction With A Hamstring Graft, Anastasios D. Georgoulis, Stavros Ristanis, Vasileios Chouliaras, Constantina O. Moraiti, Nikolaos Stergiou

Journal Articles

Recent research suggests ACL reconstruction does not re- store tibial rotation to normal levels during high demand activities when a bone-patellar tendon-bone graft is used. We asked if an alternative graft, the semitendinosus-gracilis (ST/G) tendon graft, could restore tibial rotation during a high demand activity. Owing to its anatomic similarity with the normal ACL we hypothesized the ST/G graft could re- store excessive tibial rotation to normal healthy levels along with a successful reinstatement of the clinical stability of the knee. We assessed tibial rotation in vivo, using gait analysis. We compared the knees of ACL reconstructed patients with an …

Kinetic And Kinematic Analysis Of A Judo Throwing Technique: Osoto-Gari, Noriko Narazaki, Kenji Narazaki, Nicholas Stergiou

Journal Articles

No abstract provided.

Effectiveness Of Reconstruction Of The Anterior Cruciate Ligament With Quadrupled Hamstrings And Bone-Patellar Tendon-Bone Autografts: An In Vivo Study Comparing Tibial Internal-External Rotation, Vasileios Chouliaras, Stavros Ristanis, Constantina Moraiti Moraiti, Nikolaos Stergiou, Anastasios D. Georgoulis

Journal Articles

Background: The 2 most frequently used autografts for anterior cruciate ligament reconstruction are the bone-patellar tendon- bone and the quadrupled hamstrings tendon.

Hypothesis: Hamstring tendon graft is superior to patellar tendon graft in restoring tibial rotation during highly demanding activities because of its superiority in strength and linear stiffness and because it is closer morphologically to the anatomy of the natural anterior cruciate ligament.

Study Design: Case control study; Level of evidence, 3.

Methods: Eleven patients with patellar tendon graft anterior cruciate ligament reconstruction, 11 patients with hamstring tendon graft anterior cruciate ligament reconstruction, and 11 …

Objective Assessment Of Proficiency With Bimanual Inanimate Tasks In Robotic Laparoscopy, Kenji Narazaki, D. Oleynikov, Nikolaos Stergiou

Journal Articles

Purpose: Development of objective criteria and optimum training protocols are priorities for robotic laparoscopy. However, studies that have attempted to objectify learning have been limited due to lack of task complexity and absence of comparisons between experts and novices. Our aim was to address these limitations and assess proficiency in robotic laparoscopy using bimanual inanimate tasks.

Materials and Methods: Six experts and 18 novice users of the da Vinci surgical system (Innovative Surgical, Sunnyvale, CA) performed three bimanual surgical manipulations, two of them in opposite directions, for a total of five different test tasks. During each task, elapsed time and …

A Kinematic Analysis Of Sprint Starts With Varied Starting Block Foot Placement Widths, Jesse Lee Rhoades

All-Inclusive List of Electronic Theses and Dissertations

This study examined the effect of relative lateral foot placement in the starting blocks on the sprint start. The sprinting kinematics during the first four steps out of the blocks were examined. Eight females from the a Midwest University Track and Field team performed sprint starts using a pair of modified Fusion I starting blocks. These starting blocks were made in double wide configuration to accommodate a variety of foot placements. Foot placements were determined using relative hip to ankle angle. Experimental hip-ankle angles were± five degrees (Narrow/Wide), and zero degrees (neutral). The sprinters were recorded with four cameras at …

Original Investigation Correlated Joint Fluctuations Can Influence The Selection Of Steady State Gait Patterns In The Elderly, Max J. Kurz, Nikolaos Stergiou

Journal Articles

This investigation utilized a Markov model to investigate the relationship of correlated lower extremity joint fluctuations and the selection of a steady state gait pattern in the young and elderly. Our model simulated the neuromuscular system by predicting the behavior of the joints for the next gait cycle based on the behavior exhibited in the preceding gait cycles. Such dependencies in the joint fluctuations have been noted previously in the literature. We speculated that compared to the young model, the characteristics of the correlated fluctuations in the elderly model would result in the selection of a different steady state gait …

The Locomotor Kinematics Of Asian And African Elephants: Changes With Speed And Size, John R. Hutchinson, Delf Schwerda, Daniel J. Famini, Robert H.I. Dale, Martin S. Fischer, Rodger Kram

Scholarship and Professional Work - LAS

For centuries, elephant locomotion has been a contentious and confusing challenge for locomotion scientists to understand, not only because of technical difficulties but also because elephant locomotion is in some ways atypical of more familiar quadrupedal gaits. We analyzed the locomotor kinematics of over 2400 strides from 14 African and 48 Asian elephant individuals (body mass 116-4632 kg) freely moving over ground at a 17-fold range of speeds, from slow walking at 0.40 m s^-1 to the fastest reliably recorded speed for elephants, 6.8 m s^-1. These data reveal that African and Asian elephants have some subtle …

In Situ Muscle Power Differs Without Varying In Vitro Mechanical Properties In Two Insect Leg Muscles Innervated By The Same Motor Neuron, Anna N. Ahn, Kenneth Meijer, Robert J. Full

All HMC Faculty Publications and Research

The mechanical behavior of muscle during locomotion is often predicted by its anatomy, kinematics, activation pattern and contractile properties. The neuromuscular design of the cockroach leg provides a model system to examine these assumptions, because a single motor neuron innervates two extensor muscles operating at a single joint. Comparisons of the in situ measurements under in vivo running conditions of muscle 178 to a previously examined muscle (179) demonstrate that the same inputs (e.g. neural signal and kinematics) can result in different mechanical outputs. The same neural signal and kinematics, as determined during running, can result in different mechanical functions, …

Optimal Movement Variability: A New Theoretical Perspective For Neurologic Physical Therapy, Nikolaos Stergiou, Regina T. Harbourne, James T. Cavanaugh

Journal Articles

Variability is a natural and important feature of human movement. Using existing theoretical frameworks as a foundation, we propose a new model to explain movement variability as it relates to motor learning and health. We contend that mature motor skills and healthy states are associated with an optimal amount of movement variability. This variability also has form and is characterized by a chaotic structure. Less than optimal movement variability characterizes biological systems that are overly rigid and unchanging, whereas greater than optimal variability characterizes systems that are noisy and unstable. Both situations characterize systems that are less adaptable to perturbations, …

Statistical Approach To Background Subtraction For Production Of High-Quality Silhouettes For Human Gait Recognition, Jennifer J. Samler

Theses and Dissertations

This thesis uses a background subtraction to produce high-quality silhouettes for use in human identification by human gait recognition, an identification method which does not require contact with an individual and which can be done from a distance. A statistical method which reduces the noise level is employed resulting in cleaner silhouettes which facilitate identification. The thesis starts with gathering video data of individuals walking normally across a background scene. From there the video is converted into a sequence of images that are stored as joint photographic experts group (jpeg) files. The background is subtracted from each image using a …

A 100 Meter Training Walk Using A Speed Trainers™ Device Does Not Strengthen The Hip Flexors In Collegiate Sprinters, Jayme Donald Jasper

All-Inclusive List of Electronic Theses and Dissertations

Context: Many types of resistance training programs have been implemented in order to enhance sprint performance, however, most programs have overlooked the importance of the hip flexor muscles. Objective: To determine if a training protocol using a Speed Trainers ™ device will increase hip flexion strength, and if that increase in strength has an effect on competition sprint times. Design: A 2 X 2 pre-test post-test design with treatment (hip flexor strength training and sham group) and time (pre-training and posttraining) as the independent variables. Setting: The strengthening program took place at the Indiana State University outdoor track. Competition sprint …

The Effect Of Prophylactic Ankle Bracing On Star Excursion Balance Measures In Uninjured Subjects, Lisa Marie Hardy

All-Inclusive List of Electronic Theses and Dissertations

Context: Reports of bracing on whole body bilateral movements and single directional motions are unclear about whether or not the performance of uninjured active people is affected. Objective: To isolate the braced limb, while performing multidirectional tasks, to gain a better understanding of the effects of bracing on performance. Design: A 1 X 3 repeated measures design with the bracing condition (unbraced, lace-up, and semi-rigid) as the independent variable. Setting: Laboratory. Patients or Other Participants: Thirtysix uninjured, physically-active, volunteers (M: 18, F: 18, age: 23 .6±2. 7y, ht: 173.8±9.3cm, mass: 74.4±12.7kg, reach leg length: 91.9±5.lcm). Main Outcome Measure(s): The average …

Robotic Surgery And Training: Electromyographic Correlates Of Robotic Laparoscopic Training, Timothy N. Judkins, D. Oleynikov, N. Karazaki, Nikolaos Stergiou

Journal Articles

Background: Robotic laparoscopic surgery has been shown to decrease task completion time, reduce errors, and decrease training time when compared to manual laparoscopic surgery. However, current literature has not addressed physiological effects, in particular muscle responses, to training with a robotic surgical system. We seek to determine the frequency response of electromyographic (EMG) signals of specific arm and hand muscles with training using the da Vinci Surgical System (dVSS).

Methods: Seven right-handed medical students were trained in three tasks with da Vinci Surgical System over four weeks. These subjects, along with eight controls, were tested before and after …

Examination Of Clinical And Laboratory Measures Of Postural Stability During Static And Dynamic Testing Between Stable And Unstable Ankles, Jason C. Mitchell

Human Movement Studies & Special Education Theses & Dissertations

The purposes of this study were to (1) examine the relationship between clinical and laboratory balance testing, (2) to examine the effect of functional ankle instability (FAI) on scored dynamic and static clinical balance tests, (3) to examine the effect of functional ankle instability (FAI) on a timed dynamic clinical balance test, (4) to examine the effect of FAI on a dynamic laboratory balance test, and (5) to examine the effect of FAI on a static laboratory balance test. Each subject performed four balance tests; (1) Balance Error Scoring System (BESS) Test, (2) Agility Hop test, (3) Laboratory Static Balance …

Follow-Up Evaluation 2 Years After Acl Reconstruction With Bone–Patellar Tendon–Bone Graft Shows That Excessive Tibial Rotation Persists, Stavros Ristanis, Nikolaos Stergiou, Kostas Patras, Elias Tsepis, Constantina O. Moraiti, Anastasios D. Georgoulis

Journal Articles

Objective: To investigate in vivo if the increased tibial rotation found in anterior cruciate ligament (ACL)-deficient patients before surgery is restored 2 years after the reconstruction, during 2 high-demanding activities.

Design: Prospective follow-up study.

Setting: A gait analysis laboratory.

Participants: Nine subjects with unilateral ACL rupture, reconstructed with a bone–patellar tendon–bone (BPTB) graft, and 10 healthy control subjects.

Interventions: All the ACL-deficient patients underwent a unilateral ACL reconstruction after prereconstruction data acquisition.

Main Outcome Measurements: Using a 6-camera motion analysis system, kinematics were collected as subjects (1) descended from a stair and, after foot …

Hper Biomechanics Laboratory 2005 Annual Report, Issue 4, Nebraska Biomechanics Core Facility

Biomechanics Annual Report

This issue features Dr. Stergiou Receives a K25 Award from the National Institutes of Health, Training Methods to Improve Robotic Laparoscopic Surgery, Progress Update for Federal Grant: The Development of Sitting Posture in Children with Cerebral Palsy, Pioneering Gait Analysis Research, Collaboration with UNMC Department of Surgery and VA Hospital: The Effects of Peripheral Arterial Disease on Gait, Sabbatical Strengthened Collaborations in Orthopedics, Computer Modeling with Dynamic Toys Reveals Human Gait Patterns, Prestigious Awards to Dr. Stergiou, Teachers Enriched During Final Year of Banneker 2000, New Staff Joins the HPER Biomechanics Laboratory, Noteworthy Events, Internationally Recognized Bioengineer Visited HPER Biomechanics …

A Novel Approach To Measure Variability In The Anterior Cruciate Ligament Deficient Knee During Walking: The Use Of The Approximate Entropy In Orthopaedics, Anastasios D. Georgoulis, Constantina O. Moraiti, Stavros Ristanis, Nikolaos Stergiou

Journal Articles

Objective. The evaluation of variability of biological rhythmic activities through measures such as Approximate Entropy (ApEn) has provided important information regarding pathology in disciplines such as cardiology and neurology. This research lead to the “loss of complexity hypothesis” where decreased variability is associated with loss of healthy flexibility rendering the system more rigid and unable to adapt to stresses. ApEn as a measure of variability and complexity, correlates well with pathology while, in some cases, it is predictive of subsequent clinical changes. The study of human gait could benefit from the application of ApEn since it is also a …

An Improved Surrogate Method For Detecting The Presence Of Chaos In Gait, David J. Miller, Nikolaos Stergiou, Max J. Kurz

Journal Articles

It has been suggested that the intercycle variability present in the time series of biomechanical gait data is of chaotic nature. However, the proper methodology for the correct determination of whether intercycle fluctuations in the data are deterministic chaos or random noise has not been identified. Our goal was to evaluate the pseudoperiodic surrogation (PPS) [Small et al., 2001. Surrogate test for pseudoperiodic time series data. Physical Review Letters 87(18), 188,101–188,104], and the surrogation algorithms of Theiler et al. [1992. Testing for nonlinearity in time series: the method of surrogate data. Physica D 58(1–4), 77–94] and of Theiler and Rapp …

Recovery Of Postural Control After Cerebral Concussion: New Insights Using Approximate Entropy, James T. Cavanaugh, Kevin M. Guskiewicz, Carol Giuliani, Stephen Marshall, Vicki S. Mercer, Nikolaos Stergiou

Journal Articles

Context: The return-to-play decision after sport-related cerebral concussion depends in part on knowing when an athlete has fully recovered postural control after injury.

Objective: To describe the postconcussion recovery of postural control using approximate entropy (ApEn), a regularity statistic from nonlinear dynamics.

Design: Retrospective case series analysis.

Setting: Sports medicine research laboratory.

Patients or Other Participants: Collegiate athletes from whom center-of-pressure and symptom data were collected at preseason, less than 48 hours after injury, and 48 to 96 hours after injury.

Main Outcome Measure(s): Approximate entropy values reflecting the amount of randomness contained in center-of-pressure oscillations were calculated for anterior-posterior …

Sight-Reading Versus Repertoire Performance On The Piano: A Case Study Using High-Speed Motion Analysis, Brenda Wristen, Sharon Evans, Nikolaos Stergiou

Journal Articles

The purpose of the study was to examine whether differences exist in the motions employed by pianists when they are sight-reading versus performing repertoire and determine whether these differences could be quantified using high speed motion capture technology. A secondary question of interest was whether or not an improvement in the efficiency of motion could be observed between two sight-reading trials of the same musical excerpt. This case study employed a six digital infrared camera system (Motion Analysis, Inc.) to capture the motion of pianists playing two trials of a repertoire piece and two trials of a sight-reading excerpt. Angular …

Joint Kinetics Of The Ankle And Knee When Running Over Obstacles, Alan Hreljac, Nikolaos Stergiou, Shane D. Scholten

Journal Articles

When running over obstacles of increasing height, heelstrike runners switch to a forefoot landing pattern once a critical obstacle height is reached. The primary purpose of this study was to determine whether ankle or knee joint kinetic variables trigger the gait change from a heelstrike to a forefoot striking pattern as obstacle height increases. Ten subjects were filmed from the sagittal plane as they ran at their preferred running speed over a force platform during six obstacle height conditions ranging from 10% to 22.5% of standing height, as well as an additional baseline condition with no obstacle (0%). An inverse …

A Nonlinear Dynamic Approach For Evaluating Postural Control, James T. Cavanaugh, Kevin M. Guskiewicz, Nikolaos Stergiou

Journal Articles

Recent research suggests that traditional biomechanical models of postural stability do not fully characterise the nonlinear properties of postural control. In sports medicine, this limitation is manifest in the postural steadiness assessment approach, which may not be sufficient for detecting the presence of subtle physiological change after injury. The limitation is especially relevant given that return-to-play decisions are being made based on assessment results. This update first reviews the theoretical foundation and limitations of the traditional postural stability paradigm. It then offers, using the clinical example of athletes recovering from cerebral concussion, an alternative theoretical proposition for measuring changes in …

Excessive Tibial Rotation During High-Demand Activities Is Not Restored By Anterior Cruciate Ligament Reconstruction, Stavros Ristanis, Nikolaos Stergiou, Kostas Patras, Haris S. Vasiliadis, Giannis Giakas, Anastasios D. Georgoulis

Journal Articles

Purpose: Recent in vitro research has suggested that anterior cruciate ligament (ACL) reconstruction does not restore control of tibial rotation. The purpose of this study was to explore these findings in vivo and investigate rotational knee stability during landing and subsequent pivoting. Such an activity places higher demands on the knee, almost similar to those found during high-level sports.

Type of Study: Case control series study.

Methods: We assessed 11 patients who had undergone ACL reconstruction with the same arthroscopic technique using a bone–patellar tendon–bone graft, 11 ACL-deficient subjects who had sustained the injury more than 1 year prior to …

Functional Electric Stimulation Cycle Ergometry Training Effect On Lower Limb Muscles In Acute Sci Individuals, Timothy J. Demchak, Jon K. Linderman, W. Jerry Mysiw, Rebecca Jackson, Jihong Sunn, Steven T. Devor

Health and Sport Science Faculty Publications

The purpose of this study was to compare three different intervals for a between sets rest period during a common isokinetic knee extension strength-testing protocol of twenty older Brazilian men (66.30 ± 3.92 yrs). The volunteers underwent unilateral knee extension (Biodex System 3) testing to determine their individual isokinetic peak torque at 60, 90, and 120° ·s-1. The contraction speeds and the rest periods between sets (30, 60 and 90 s) were randomly performed in three different days with a minimum rest period of 48 hours. Significant differences between and within sets were analyzed using a One Way Analysis of …

An Artificial Neural Network That Utilizes Hip Joint Actuations To Control Bifurcations And Chaos In A Passive Dynamic Bipedal Walking Model, Max J. Kurz, Nikolaos Stergiou

Journal Articles

Chaos is a central feature of human locomotion and has been suggested to be a window to the control mechanisms of locomotion. In this investigation, we explored how the principles of chaos can be used to control locomotion with a passive dynamic bipedal walking model that has a chaotic gait pattern. Our control scheme was based on the scientific evidence that slight perturbations to the unstable manifolds of points in a chaotic system will promote the transition to new stable behaviors embedded in the rich chaotic attractor. Here we demonstrate that hip joint actuations during the swing phase can provide …

Electromechanical Delay Of The Knee Extensor Muscles Is Not Altered After Harvesting The Patellar Tendon As A Graft For Acl Reconstruction: Implications For Sports Performance, Anastasios D. Georgoulis, Stavros Ristanis, Anastasios Papadonikolakis, Elias Tsepis, U. Moebius

Journal Articles

Although the scar tissue, which heals the donor site defect, has different elasticity from the neighbouring patellar tissue, it remains unclear if this scar tissue can lead to the changes of the electromechanical delay (EMD) of the knee extensor muscles. If such changes do exist, they can possibly affect both the utilization of the stored energy in the series elastic component, as well as the optimal performance of the knee joint movement. The purpose of this study was to investigate the influence of harvesting the patellar tendon during anterior cruciate ligament (ACL) reconstruction and the associated patellar tendon scar tissue …

Anterior Cruciate Ligament Reconstruction With A Quadrupled Hamstring Autograft Does Not Restore Tibial Rotation, Anastasios D. Georgoulis, Stavros Ristanis, Vasilis Chouliaras, Constantina O. Moraiti, Nikolaos Stergiou

Journal Articles

As a result of the morbidity associated with anterior cruciate ligament (ACL) reconstruction with a bone–patellar–tendon– bone graft, many orthopaedic surgeons prefer hamstrings as the graft for ACL reconstruction. However, this selection is not based on solid scientific evidence. In vitro research shows that this graft cannot restore control of tibial rotation. Our recent in vivo research work has also demonstrated the same result. In particular, patients undergoing ACL repair who were reconstructed with a quadrupled hamstring tendon graft showed excessive tibial rotation during a dynamic activity when compared with healthy control subjects. Although the hamstring tendon graft has a …

The Influence Of Landing Technique Versus Technique And Strength Training On Valgus Knee Deformity In Females, Kirsten R. Holmes

Masters Theses

The purpose of this study was to evaluate the effectiveness of landing technique training versus landing technique and plyometric/strength training program on knee valgus during landing in females. Subjects participated in a 6-week training program. A 2 X 3 repeated measures ANOVA with two within subjects’ factors Test and Group was used to test for differences in the knee valgus angle in the landing condition and the five jump condition. A 2 x 2 repeated measures ANOVA with two within subjects’ factors, was used to test for difference in knee extension strength and knee flexion strength. Pre-test knee-valgus 4.76 ± …

Ankle Bracing Does Not Affect Force Development During A Single-Legged Vertical Jump, John M. Ibarra

All-Inclusive List of Electronic Theses and Dissertations

Objective: The effect of prophylactic ankle bracing on functional performance and isolated joint torque has been well studied. However, the potential effect of external 111 ankle support on force production during a sport-specific task remains unknown. Thus, the purpose of this study was to examine the potential effects of two widely used prophylactic ankle braces on lower extremity force development while performing a onelegged vertical jump. Design and Setting: A 1 x 3 factorial was used in this study. The single independent variable was ankle brace with 3 levels: 1) Semi-rigid ankle brace; 2) Lace-up style brace; and 3) control …