Biomedical subjects

Zlatko Matjacić

Publications and source records attributed to Zlatko Matjacić.

11 recordsLinked to original sources

PubMed2007

Apparatus for dynamic balance training during treadmill walking.

OBJECTIVE: A presentation of a novel apparatus for dynamic balance training during treadmill walking, which was tested in a case study. SUBJECT: The subject was a man with incomplete chronic spinal cord injury (C5), graded D on the American Spinal Injury Association Impairment Scale. METHODS: Following a 6-month baseline period, 4 weeks of control treatment (treadmill walking) and a subsequent 4 weeks of experimental treatment (treadmill walking assisted by the apparatus) were compared. Outcome measures were Lower Extremities Motor Score, Berg Balance Scale, 10-metre walking test and 9-minute walking test. RESULTS: During the baseline period the changes in the outcome measures were small. After the control treatment the balance score remained unchanged, while walking speed and walking endurance increased moderately. Experimental treatment resulted in further substantial changes in balance and walking endurance scores, while further increase in walking speed was moderate. At follow-up these values were maintained. Lower Extremities Motor Scores were almost identical in all study phases. CONCLUSION: The subject's walking and balancing abilities improved moderately after the control treatment, while greater improvement occurred during experimental treatment. This indicates that the apparatus developed might be an important tool for facilitating dynamic balancing training during treadmill walking.

Adult↗

PubMed2006

Effects of dynamic balance training during standing and stepping in patients with hereditary sensory motor neuropathy.

PURPOSE: To quantitatively evaluate the effects of dynamic balance training in patients with hereditary sensory motor neuropathy (HSMN). METHODS: Sixteen patients with HSMN were randomly assigned to either an experimental or control group. The intervention session consisted of passive stretching, muscle strengthening and dynamic balance training during standing and stepping, which differed in that the experimental group used commercially available balance training mechanical apparatus while the patients from the control group were physically managed by a physiotherapist. The intervention period was 12 days. Balance and mobility functions were assessed by means of Berg Balance Scale, Up&go test and 10-m walk test before and after the intervention period. RESULTS: The within-group comparison (1-way repeated measures ANOVA) for the experimental group showed statistically significant improvement (p < 0.05) in Berg Balance Scale, Up&go test and 10-m walk test, while within-group comparison for the control group showed statistically significant improvement only in Berg Balance Scale (p < 0.05). The between-group comparison (2-way ANOVA) showed larger improvement in the experimental group, however, these differences were not statistically significant. CONCLUSION: Dynamic balance training is useful training modality for patients with HSMN. When exercised in the balance training mechanical apparatus used in this study enables efficient balance and mobility training without requiring physical assistance from a physiotherapist or a caregiver, which opens new possibilities for continuing and more frequent physical exercise and mobility training of patients with HSMN also at their homes.

Adolescent↗

PubMed2006

Biomechanical characterization and clinical implications of artificially induced crouch walking: Differences between pure iliopsoas, pure hamstrings and combination of iliopsoas and hamstrings contractures.

The purpose of this study was to characterize biomechanically three different crouch walking patterns, artificially induced in eight neurologically intact subjects and to compare them to selected cases of pathological crouch walking. The subjects were equipped with a lightweight mechanical exoskeleton with artificial muscles that acted in parallel with hamstrings and iliopsoas muscles. They walked at a speed of approximately 1m/s along the walkway under four experimental conditions: normal walking (NW), hamstrings contracture emulation (HAM), iliopsoas contracture emulation (IPS) and emulation of both hamstrings and iliopsoas contractures (IPSHAM). Reflective markers and force platform data were collected and ankle, knee and hip-joint angles, moments and powers were calculated. HAM and IPSHAM shifted ankle-angle rotation profiles into dorsiflexion during midstance compared to IPS and NW where ankle-angle trajectories were similar. HAM, IPS and IPSHAM shifted the knee angle of rotation profiles into flexion during stance, compared to NW. IPS and IPSHAM shifted hip angle of rotation profiles toward pronounced flexion while HAM shifted hip angle of rotation profile toward extension, compared to NW. HAM and IPSHAM significantly increased ankle moment during midstance, compared to IPS and NW where ankle moment profiles were similar. All experimental conditions exhibited similar behavior in the knee-moment profiles during midstance while IPS and IPSHAM knee-moment profiles exhibited significantly higher knee-extension moment during terminal stance and pre-swing. In the hip joint all experimental conditions exhibited similar shape of hip moment profiles throughout the gait cycle. HAM and IPS kinematic and kinetic patterns were qualitatively compared to two selected clinical cases, showing considerable similarity. This implies that distinct differences in kinematics and kinetics between HAM, IPS and IPSHAM may be clinically relevant in helping determine the relative contribution of hamstrings and iliopsoas muscles contractures to particular crouch walking.

Adult↗

PubMed2006

Biomechanical characterization and clinical implications of artificially induced toe-walking: differences between pure soleus, pure gastrocnemius and combination of soleus and gastrocnemius contractures.

The purpose of this study was to characterize biomechanically three different toe-walking gait patterns, artificially induced in six neurologically intact subjects and to compare them to selected cases of pathological toe-walking. The subjects, equipped with lightweight mechanical exoskeleton with elastic ropes attached to the left leg's heel on one end and on shank and thigh on the other end in a similar anatomical locations where soleus and gastrocnemius muscles attach to skeleton, walked at speed of approximately 1m/s along the walkway under four experimental conditions: normal walking (NW), soleus contracture emulation (SOL), gastrocnemius contracture emulation (GAS) and emulation of both soleus and gastrocnemius contractures (SOLGAS). Reflective markers and force platform data were collected and ankle, knee and hip joint angles, moments and powers were calculated using inverse dynamic model for both legs. Characteristic peaks of averaged kinematic and kinetic patterns were compared among all four experimental conditions in one-way ANOVA. In the left leg SOL contracture mainly influenced the ankle angle trajectory, while GAS and SOLGAS contractures influenced the ankle and knee angle trajectories. GAS and SOLGAS contractures significantly increased ankle moment during midstance as compared to SOL contracture and NW. All three toe-walking experimental conditions exhibited significant power absorption in the ankle during loading response, which was absent in the NW condition, while during preswing significant decrease in power absorption as compared to NW was seen. In the knee joint SOL contracture diminished, GAS contracture increased while SOLGAS contracture approximately halved knee extensor moment during midstance as compared to NW. All three toe-walking experimental conditions decreased hip range of motion, hip flexor moment and power requirements during stance phase. Main difference in the right leg kinematic and kinetic patterns was seen in the knee moment trajectory, where significant increase in the knee extensor moment took place in terminal stance for GAS and SOLGAS experimental conditions as compared to SOL and NW. The kinetic trajectories under SOL and GAS experimental conditions were qualitatively compared to two selected clinical cases showing considerable similarity. This implies that distinct differences in kinetics between SOL, GAS and SOLGAS experimental conditions, as described in this paper, may be clinically relevant in determining the relative contribution of soleus and gastrocnemius muscles contractures to toe-walking in particular pathological gait.

Adaptation, Physiological↗

PubMed2005

Sensory supported FES control in gait training of incomplete spinal cord injury persons.

Sensory supported electrical stimulation of the peroneal nerve during treadmill walking is proposed as a gait-training modality in incomplete spinal cord injury (SCI) patients. A multisensor device provides information on the tilt of the shank during gait. The information provided significantly improves the triggering instant of the electrical stimulation. Simultaneously, swing-phase estimation serves as a reference to determine the required motor augmentation support. Both approaches, as well as triggering using intensity control of the functional electrical stimulation were applied on a healthy person and on an incomplete C4-5 SCI patient.

Biofeedback, Psychology↗

PubMed2005

Methods for dynamic balance training during standing and stepping.

The regaining of walking ability is one of the main goals of rehabilitation following stroke. An important aspect of bipedal locomotion is efficient balancing of the trunk. In this article a novel methodology for dynamic balance training during standing and stepping is presented in a commercially available mechanical balance training device. A case study that lasted for two-weeks with two half-hour training sessions per day, involving a single subject with chronic hemiparesis, investigated the effects of the proposed dynamic balance training. Instrumented kinesiological evaluation of the subject's gait indicated important improvement in the subject's postural control during walking. Finally, the possibility of combining therapeutic functional electrical stimulation of selected lower extremity muscles with the methodology for dynamic balance training presented here is discussed.

Hemiplegia↗

PubMed2003

Foot-sole reflex receptive fields for human withdrawal reflexes in symmetrical standing position.

Human withdrawal-reflex receptive fields were assessed in 10 healthy subjects during standing with even support on both legs. Two electrical-stimulus intensities (1.2 and 2.2 times the pain threshold, PTh) were used. The painful stimuli were delivered in random order to 12 positions distributed over the foot sole. Tibialis anterior (TA), soleus (SO), vastus lateralis (VL), semitendinosus (ST), and iliopsoas (IL) reflexes were recorded. Further, the vertical force was recorded and the center or pressure (CoP) was assessed in the frontal and sagittal planes on both legs. Reflexes were observed at both intensities with the strongest reflexes at the high intensity. Around the ankle joint, SO reflexes dominated, which is in contrast to previous observations for subjects sitting. An unloading of the limb was found on the stimulated leg associated with a simultaneous loading of the contralateral leg. The shift in load was most pronounced for stimulation of the heel. The flexors ST and IL also had strong reflexes with reflex patterns correlated to the pattern of unloading. The shift in vertical force was accomplished by a move of the CoP in the anterior direction on the stimulated limb (contraction of SO), which simultaneously caused a small movement of the CoP in the lateral direction. In the present standing conditions, the ankle extensor played a dominant role in the withdrawal pattern in contrast to previous studies during sitting, relaxed conditions.

Adult↗

PubMed2003

Development of a gait re-education system in incomplete spinal cord injury.

OBJECTIVE: The aim of the paper is to present the development of a system for swing phase restoration in patients with incomplete spinal cord injury. METHODS: The functional electrical stimulation based gait re-education system comprises a sensory system, a system providing cognitive feedback and a motor augmentation system facilitating and correcting the movement of the swinging extremity. Mathematical algorithms estimate swing quality and classify the swing phase of walking into 3 levels, termed cognitive feedback, which is provided to the patient as an auditory signal. A single-channel peroneal functional electrical stimulation was applied as a motor augmentation system to provide the patient with the motor assistance required. The important novelty of the proposed system is that motor assistance is provided only at the level that enables the patient to perform a good swing. RESULTS: The developed system was tested in a patient with incomplete spinal cord injury, with C4-5 lesion, whilst walking on a treadmill. The results show that the automated sensory-driven functional electrical stimulation augmentation system, providing only the minimal assistance required based on the subject's performance, is a viable approach that successfully releases a therapist from the task of delivering properly timed stimulation of adequate intensity in assisting the swing phase of walking.

Adult↗

PubMed2003

BalanceReTrainer: a new standing-balance training apparatus and methods applied to a chronic hemiparetic subject with a neglect syndrome.

In this paper we present a mechanical apparatus and methods named BalanceReTrainer for standing-balance training in neurologically impaired individuals. BalanceReTrainer provides an impaired individual with a fall-safe balancing environment, where the balancing efforts of a standing individual are augmented by stabilizing forces acting at the level of pelvis in the sagittal and frontal planes of motion, assisting the balancing activity ankle and hip muscles and at the level of shanks, assisting the knee extensor muscles. A range of different levels of supporting forces is generated by passive, compliant means. Additionally, movement in the sagittal and frontal planes, acquired by transducers is fed to an electronic interface which transforms the current inclinations into a computer mouse signals, which are interfaced to a personal computer (PC) where balance training and evaluation program is running. The level of stiffness support and level of difficulty of computer task can be selected according to current balancing abilities of the impaired individual. We further present results of a case study where an ambulatory chronic hemiparetic subject with neglect syndrome received ten days of balance training on BalanceReTrainer. Biomechanical evaluation of weight-shifting activity before and after treatment shows a substantial functional improvement.

Adult↗

PubMed2002

Paraplegic standing supported by FES-controlled ankle stiffness.

The objective of this paper was to investigate whether a paraplegic subject is able to maintain balance during standing by means of voluntary and reflex activity of the upper body while being supported by closed loop controlled ankle stiffness using FES. The knees and hips of the subject were held in extended positions by a mechanical apparatus, which restricted movement to the sagittal plane. The subject underwent several training sessions where the appropriate level of stiffness around the ankles was maintained by the mechanical apparatus. This enabled the subject to learn how to use the upper body for balancing. After the subject gained adequate skills closed-loop FES was employed to regulate ankle stiffness, replacing the stiffness provided by the apparatus. A method to control antagonist muscle moment was implemented. In subsequent standing sessions, the subject had no difficulties in maintaining balance. When the FES support was withheld, the ability to balance was lost.

Adult↗

PubMed2002

The biomechanics of standing and balancing in paralyzed people.

Prolonged immobilization results in several physiological problems. It has been demonstrated that standing exercises can ameliorate many of these problems. Standing exercises can be performed efficiently with the help of functional electrical stimulation (FES). A novel robotic mechanism which aids the unsupported standing of paraplegics, providing balancing exercise has been developed. The balancing strategy is based on voluntary activity of the paraplegic's upper body and artificially controlled stiffness in the ankles.

Adult↗