Dynamic stability evaluation of trunk accelerations during walking in blind and sighted individuals.

BACKGROUND: Dynamic stability is a fundamental goal in standing activities. In this regard, monitoring, analysis, and interventions made to improve stability is a research topic investigated in the biomechanics of human movements. Vision has a major role to play in controlling human movement. Nonetheless, little is known about the effects of visual deprivation, especially from birth on dynamic gait stability. METHODS: The current study was conducted on 20 congenital blind and 10 sighted people (15-38 years). To evaluate the dynamic stability, descriptive data, harmonic ratio (HR), improved harmonic ratio (iHR), and root mean square (RMS), based on trunk acceleration data were measured in three axes: anteroposterior (AP), vertical (V), and mediolateral (ML) while participants walked an eight-meter straight path. RESULTS: In the comparison of blind and sighted people (eyes open), standard deviation, HR, iHR, and RMS indices were found to be significantly different in both AP and V directions. All the mentioned parameters were significantly lower in blind than in sighted participants. In the comparison of blind people and sighted ones with closed eyes, changes were observed in the maximum, range, standard deviation, and RMS only in the AP axis. In the comparison between eyes open and closed in sighted people, a significant difference was found only in the harmonic ratio of the vertical axis. CONCLUSION: Visual deprivation led to a decrease in dynamic stability parameters in the AP and V axes. Even the movement of sighted people in unchallenged conditions is dependent on visual information.

Quantitative EEG for the Monitoring of Walking Recovery in Chronic Stroke Patients Receiving Action Observation Training.

The current study aimed to evaluate the effects of action observation on the walking ability and oscillatory brain activity of chronic stroke patients. Fourteen chronic stroke patients were allocated randomly to the action observation (AO) or sham observation (SO) groups. Both groups received 12 sessions of intervention. Each session composed of 12 min of observational training, which depicted exercises for the experimental group but nature pictures for the sham group and 40 min of occupational therapy, which was the same for the both groups. Walking ability was assessed by a motion analysis system and brain activity was monitored using quantitative electroencephalography (QEEG) before and after the intervention. Brain asymmetry at alpha frequency, the percentage of stance phase, and step length showed significant changes in the AO group. Only the change in global alpha power was significantly correlated with the change in velocity after the intervention in AO group. Despite more improvements in walking and brain activity of patients in the AO group, our study failed to show significant correlations between the brain activity changes and functional improvements after the intervention, which might be mainly due to the small sample size in our study. Trial registration: IRCT20181014041333N1.

The comparison between various methods of mandibular reconstruction based on finite element analysis.

The Mandible can be damaged by pathological factors, tumors, trauma, infection, and needs a surgical operation for reconstruction and restoring function. There are different methods for the reconstruction of mandible. Based on the surgical approach, primary reconstruction of mandible by reconstruction plate after resection is necessary for maintaining mandibular symmetric and esthetic of the lower third of the face. A finite element model of mandible and masticatory muscles was produced from a normal person (male with 35-year-old). The normal model was resected from the left sixth tooth to the second tooth. The pathological model was reconstructed in different conditions by macro plate. Different conditions were analyzed and compared based on bite force on right fifth tooth, stress developed on screws and macro plate. The finite element analysis results showed that maximum bite force and lower stress on screws were seen in the pathological model (condition 5) when one macro plate and six screws were inserted in the mid-body. The findings showed that the use of two macro plates causes lower stress on it than when we use one. Use of one macro plate and six screws is the best choice in mandibular immobilization which decrease the stress applied on bone and increase the bite force. Because of less stress developed on macro plates and screws, use of two macro plates or one macro plate in mid-body area are also preferred.

Respiratory Function Assessment through Kinematic Analysis of Chest Wall Movements: Effects of Position and Gender.

Background: The effect of position and gender on chest movements and respiratory volumes is controversial and investigated in only a few studies. Objective: This study aimed to investigate the effects of position and gender on the breathing pattern during four different positions in healthy individuals. Material and Methods: In this cross-sectional study, twenty-eight (14 males, 14 females) healthy individuals participated aged 20-45 years. The optoelectronic plethysmography (OEP) method was used for the three-dimensional evaluation of chest wall motions and the compartmental analysis of the breathing pattern in supine, sitting, standing, and active straight leg raised (ASLR) positions. Volume changes in different parts of the chest wall were also measured. Results: Position affected total and compartmental respiratory volumes in both genders. Respiratory volumes decreased in the supine position compared to sitting and standing. Total and abdominal respiratory volumes also decreased in females when comparing supine positions with the ASLR. A higher pulmonary rib cage contribution was identified in females, and males exhibited higher abdominal rib cage volume compared with females. Conclusion: The breathing pattern was affected by position and gender, and the respiratory volumes increased in more upright positions, perhaps due to a greater gravitational load. The ASLR decreases the respiratory volume, which is probably due to increased postural demand.

Evaluation of Various Fixation Methods in Acute Scapholunate Dissociation, A Finite Element Study.

Objective: This study aimed to compare the outcomes of fixing scapholunate with pins and screws in parallel, convergent, and divergent orientations. Materials and Methods: In this computer simulation study, the CT scan images of a healthy subject were used to construct a 3D model of the wrist joint using MIMICS software. The imposed force to scaphoid and 3D model lunate bones, as well as the scapholunate angle and distance, were compared in different surgical techniques using parallel, divergent, and convergent pins and screws. Results: In the absence of external force, the imposed stress applied to the scaphoid and lunate bones in cases of parallel pins and screws were 7.5MPa, 5.08MPa (pins), 1.134MPa, and 1.151MPa (screws), and 10.90MPa, 10.90MPa (pins), 9.7MPa, and 34.1MPa (screws) for 50N flexion force. The imposed stress in this approach is significantly lower compared to other interventions. Better outcomes were seen regarding scapholunate angle and scapholunate distance in using parallel pins or screws as well. Conclusion: In conclusion, implementing parallel pins and screws for scapholunate fixation had better results in terms of achieving carpal stability in scapholunate dissociation. However, fixation with pins and screws showed a statistically significant difference. Furthermore, a wide range of motion exercises with no additional forces can be used in the rehabilitation of patients undergoing this surgery.

Assessment of the effects of white cane variables on step symmetry of blind individuals.

BACKGROUND: Step symmetry is an important feature of human gait and is often regarded as a key index of healthy individuals' walking. This study evaluated the effects of height, white cane technique, and cane tip on symmetrical gait in blind individuals. MATERIALS AND METHODS: Twenty blind and ten sighted subjects, aged 15-38 years, participated in this study. The harmonic ratio (HR) and improved HR (iHR) were measured by trunk accelerometer as gait symmetry index in three axes: anteroposterior (AP), vertical, and mediolateral of the body. These parameters were measured in the sighted group in open-eye conditions and in the blind group in five experimental conditions with different two heights (standard and long), two tips (pencil and roller), and two techniques (two-point touch and constant contact) of white cane when they walked in the 6-m path. RESULTS: There was a significant difference between HR and iHR of the blind and sighted group, which indicates a significant reduction of symmetry loss in the blind group. Among the five different conditions studied in the group of blind people, an increase was observed in the HR and the iHR on the AP axis during the application of a standard cane with a roller tip, which indicated an increase in symmetry. CONCLUSION: Based on the results, a long cane with a pencil tip and a standard cane with a roller tip in the constant contact technique can increase step symmetry.

Custom-Made Ethyl Vinyl Acetate Insoles with Arch Support Could Improve Static Balance in Diabetic Women with Neuropathic Foot.

BACKGROUND: Individuals with diabetic neuropathy may experience plantar ulcers and postural instability. Although use of an insole with arch support has the potential to decrease the incidence of plantar ulcers, the choice of proper design and material density concerning postural stability is challenging. The objective of this pilot study was to conduct a preliminary evaluation of the immediate effects of custom-made ethyl vinyl acetate insoles with arch support and Shore A values of 30 or 50 on static balance in patients with diabetes and neuropathic foot/feet. METHODS: Ten women with diabetes participated in this study. Static balance was analyzed while in double-limb standing with eyes closed and eyes open and while standing on a dominant limb with eyes open wearing shoes only and wearing shoes and insoles with Shore A values of 30 and 50. RESULTS: With insole, the mean values of center of pressure excursions decreased significantly while standing on double limbs with eyes closed. The improvement in static balance was greater while using the insole with greater density; however, the difference was not statistically significant. CONCLUSIONS: An insole with arch support made of ethyl vinyl acetate Shore A of 30 and 50, which could decrease plantar pressure concentration, had no negative effect on the static balance of diabetes. Therefore, further research on the long-term effects of such insoles on the static balance of diabetes is suggested.

Investigating Glenohumeral Joint Contact Forces and Kinematics in Different Keyboard and Monitor Setups using Opensim.

Background: The musculoskeletal complaints of the shoulder are prevalent in people who work with computers for a long time. Objective: This study aimed to investigate the glenohumeral joint contact forces and kinematics in different keyboards and monitor setups using OpenSim. Material and Methods: Twelve randomly selected healthy males participated in an experimental study. A 3×3 factorial design was used in which three angles were considered for the monitor and three horizontal distances for the keyboard while performing standard tasks. The workstation was adjusted based on ANSI/HFES-100-2007 standard to maintain a comfortable ergonomic posture for controlling confounding variables. Qualisys motion capture system and OpenSim were used. Results: The maximum mean range of motion (ROM) of both shoulders' flexion and adduction was observed when the keyboard was 15 cm from the edge of the desk, and the monitor angle was 30°. The maximum mean ROM of both shoulders' internal rotation was recorded for the keyboard at the edge of the desk. Peak forces for most right shoulder complex muscles were obtained in two setups. 3D shoulder joint moments were significantly different among nine setups (P-value<0.05). The peak anteroposterior and mediolateral joint contact forces were recorded for the keyboard at 15 cm and the monitor at zero angles (0.751 and 0.780 N/BW, respectively). The peak vertical joint contact force was observed for the keyboard at 15 cm and the monitor at 15° (0.310 N/BW). Conclusion: The glenohumeral joint contact forces are minimum for the keyboard at 8 cm and the monitor at zero angles.

Evaluation of Mandibular Movements in Patients with Bell's Palsy Using Kinematic Variables.

Background: Since the function of muscles, and subsequently the mandibular joint, is affected in patients with Bell's palsy, therefore, the evaluation of facial muscles and mandibular function in these patients can be effective in diagnosis, prevention, and treatment planning. The present study aimed to evaluate the degree of displacement and range of motion (ROM) of the mandible and the ability of the facial symmetrical muscles of patients with Bell's palsy. Methods: This was a quasi-experimental comparative study. The variables evaluated were mandibular movement in a vertical direction and side-to-side displacement. Ten patients with Bell's palsy and 10 healthy eligible volunteers participated in the present study. Three mobile video cameras (to record jaw movements), 9 color markers, Kinovea software, House-Brackmann index, Toledo protocol, and a specialized patient questionnaire were used. Descriptive and inferential statistics were used for data analysis, the Kolmogorov-Smirnov test was used to investigate the normality of data distribution, and independent samples the t test and paired samples t test were used to compare means. Results: The maximum lateral on the sound side was 12.40 and 4.49 mm during lateral movements of the patients' mandible, while this value was between 12.30 and 3 mm on the involved side. There is a difference between the affected side and the nonaffected side in terms of the mean lateral movements of the patients' mandible. However, this difference in the mean ROM on both sides is not statistically significant. The maximum mouth opening in healthy individuals during mandibular movements was between 40 and 60 mm, while this value was between 25 and 50 mm in the patients with Bell's palsy. This study shows a significant difference (P = 0.007) between patients and healthy individuals in terms of the mean of maximum mouth opening ( P < 0.05). Conclusion: The results of this study showed that the ROM of temporomandibular joint (TMJ) of the patient is the same as that of normal subjects, but the side-to-side motion is more than normal which should be considered in rehabilitation treatments. The present study emphasizes the need to implement a mandibular kinematic evaluation protocol in patients with bell's palsy to prevent damage to the TMJ in the long term.

Static and local dynamic stability of subjects with knee joint osteoarthritis.

Stability is defined as the ability to control the amplitude and velocity of center of gravity (CoG) changes during quiet standing, and to decrease the risk of falling during walking. Few studies exist which examine the local dynamic stability of those with knee joint osteoarthritis (OA). Nevertheless, it is debatable whether the stability of OA subjects differs from that of normal subjects or not. The aim of this study was to evaluate the static and local dynamic stability of the subjects with knee OA in comparison to normal subjects. Fifteen OA subjects and 15 healthy subjects with matching age, weight, and gender participated in this study. A Qualysis motion analysis system incorporating a Kistler force plate was used to record data during quiet standing and when walking on a treadmill. Static stability was evaluated based on center of pressure (COP) sways excursion, path length and velocity in mediolateral and anteroposterior axes. Local dynamic stability was evaluated by the use of short Lyapunov exponent when subjects walk on treadmill. A two-sample test-test was used for the final analysis (α = 0.05). Mean values of the COP excursion in mediolateral and anteroposterior directions, and the velocity of COP in both mediolateral and anteroposterior directions, differed significantly between healthy and OA subjects (p < 0.05). Local dynamic stability of OA subjects appeared to be reduced compared to healthy subjects, especially when ambulating at higher walking speeds (p-value < 0.05). Study results demonstrated that both static and local dynamic stability decreased in OA subjects. This may be in part due to altered control mechanisms which are required for response to perturbations during standing and walking to ensure stability. As a decrease in local dynamic stability is correlated to an increased risk of falling, it is important that this group should receive appropriate treatment interventions to improve standing and walking stability.

The effect of toe-only rocker sole shoes on gait variability of the elderly.

Gait variability could associate with fall risk in older people. Rocker sole shoes are commonly prescribed to reduce plantar pressure and facilitate forward movement. Thus, it may affect gait stability. The purpose of this study was to investigate the effects of toe-only rocker shoes on gait variability in the elderly. Seventeen healthy elderly participants walked on a treadmill under six different conditions including barefoot (BF), normal shoe (NS), and four types of toe-only rocker sole shoes with various degrees of rocker angle (RS10, RS20, RS30, and RS40). Then the step length variability (SLV), the step time variability (STV), the step width variability (SWV), and the stance time variability were measured. Increasing rocker angle in toe-only rocker did not significantly affect gait variability more than the standard shoe. It seems that different rocker angles in toe-only rocker sole shoes do not pose a threat to gait variability compared to the standard shoes in healthy elderly. Findings of the study suggested that the toe-only rocker sole can be used to facilitate forward progression in the elderly. Further investigation is also required to examine the long-term effects of toe-only rocker sole shoes on gait variability in frail elderly.

Investigating the Effect of Keyboard Distance on the Posture and 3D Moments of Wrist and Elbow Joints among Males Using OpenSim.

Musculoskeletal disorders (MSDs) of the upper extremities and computer use are common in modern societies, and both show a growing trend. This study was conducted to determine the posture and 3D moments of wrist and elbow joints at different keyboard distances on a desk. Twelve healthy right-handed male volunteers attended the motion analysis laboratory. A keyboard was placed at three different distances from the participants' bodies while performing a standard computer task. The workstation was adjusted according to ANSI/HFES-100-2007 standard for each participant to maintain a comfortable ergonomic posture for controlling confounding variables. Qualisys motion capture system, OpenSim (Ver. 4.1), and visual analog scale were used to collect and analyze the data. The highest levels of wrist flexion and radial deviation as well as elbow flexion and pronation were observed when the keyboard was at the edge of the desk. When the keyboard was 8 cm away from the edge of the desk, the right wrist flexion and radial deviation decreased 83% and 89%, respectively. In the left wrist, flexion and radial deviation decreased 94%. With increasing the distance of the keyboard from the edge of the desk, the right elbow flexion, pronation, and left elbow flexion decreased, 95%, 76%, and 85%, respectively. No significant difference was found for the left elbow pronation, wrist, and elbow joint moments, in the studied keyboard distances. However, a cut-off point has to be specified because large keyboard distances cause high extension and flexion of the limbs. The keyboard position relative to the body is an important parameter in computer work and has a significant impact on the posture of the upper extremities. A keyboard should be located at a distance that allows the upper extremities to remain in a neutral position so that the risk of MSDs is reduced.

Comparison of the knee joint reaction force between individuals with and without acute anterior cruciate ligament rupture during walking.

BACKGROUND: Anterior cruciate ligament plays a significant role in knee joint stability. It is claimed that the incidence of knee osteoarthritis increases in individuals with anterior cruciate ligament (ACL) rupture. The aim of this study was to evaluate the knee joints reaction force in ACL rupture group compared to normal subjects. METHOD: Fifteen patients with acute ACL rupture and 15 healthy subjects participated in this study. The ground reaction force (GRF) and kinematic data were collected at a sampling rate of 120 Hz during level-ground walking. Spatiotemporal parameters, joint angles, muscle forces and moments, and joint reaction force (JRF) of lower extremity were analyzed by OpenSIM software. RESULTS: The hip, knee and ankle joints reaction force at loading response and push-off intervals of the stance phase during walking was significantly higher in individuals with ACL rupture compared to healthy controls (p value < 0.05). Walking velocity (p value < 0.001), knee (p value = 0.065) and ankle (p value = 0.001) range of motion in the sagittal plane were significantly lower in the patients with ACL rupture compared to healthy subjects. The mean value of vertical GRF in the mid-stance, the peak of the hip adduction moment in loading response and push-off phases, the hip abductor, knee flexor and vastus intermedius part of quadriceps muscle forces were significantly higher compared to healthy subjects (p < 0.05) while vastus medialis and vastus lateralis produced significantly lower force (p < 0.001). CONCLUSIONS: Based on results of this study, lower limb JRF was higher in those with ACL rupture compared to healthy subjects may be due to the compensatory mechanisms used by this group of subjects. An increase in knee JRF in patients with ACL rupture may be the reason for the high incidence of knee OA.

The effect of rocker sole shoes on ground reaction force in the elderly.

Aging is associated with decreases in gait performance and mobility. Toe-only rocker sole is prescribed as a common shoe modification in restricted foot and ankle joints mobility. Therefore, this study aimed to determine the effect of toe-only rocker sole shoes on the ground reaction force (GRF) in the elderly. Twenty-one older adults walked on a walkway equipped with one force plate under six different conditions including barefoot (BF), normal shoe (NS), and four types of toe-only rocker sole shoes (RS) with various degrees of rocker angle (RS10, RS20, RS30, and RS40). The peaks of the GRFs in three planes were obtained. Different rocker angles could affect GRF parameters. The first peak of GRF (FZ1) significantly increased with both RS30 and RS40 compared to BF, NS, RS10, and RS20. FZ1 significantly decreased with RS30 compared to RS40. The braking force (FX1) was significantly lower with NS compared to RS30 and RS40. FX1 was significantly higher with RS40 compared to the other shoe conditions. The propulsive force (FX2) significantly decreased during walking with BF compared to NS, RS20, RS30, and RS40. A higher FX2 was observed in RS40 than the other shoe conditions except RS30. Also, FX2 was significantly lower with RS10 compared to RS30. Increasing rocker angle may result in an increase in the peak magnitude of FZ1, FX1, FX2 in the elderly without any improvement in walking speed.

The effects of action observation training as an add-on rehabilitation strategy on the walking ability of patients with chronic stroke.

OBJECTIVE: Stroke is one of the most debilitating neurological disorders that commonly results in both cognitive and motor dysfunctions. Although the recovery of gait is one of the main goals of patients with stroke, only 50-60% of the patients commonly reach this target. This study aimed to evaluate the effects of action observation training, based on mirror neurons, as an add-on therapy to the conventional physical rehabilitation on the gait performance of patients with stroke. METHODS: Fourteen patients with chronic stroke were randomly assigned to the sham or the experimental group. Both groups received a 40-min conventional physical training following a 12-min observation training depicting exercises for the experimental group but nature pictures for the sham group each session. The patients' walking was recorded using a motion analysis system at baseline and after the 12-session intervention. Spatiotemporal parameters of gait and ground reaction forces were measured. RESULTS: Significant improvements were found in most measured spatiotemporal parameters of gait on the unaffected side of the patients in the experimental group, while in the sham group, the recovery was observed only in the percentage of the stance phase. Regarding the affected side, the stride and step length of the patients in the experimental group were parameters with a significant amelioration. CONCLUSION: The results of this study showed that the action observation training had the potential to improve the walking quality of the patients with hemiplegia in the chronic phase of stroke.

Evaluation the Efficiency of Electrical Stimulation Advanced Methods on Management of Bowel and Bladder Functions in Spinal Cord Injury Subject; A Systematic Review of Literature.

OBJECTIVE: To evaluate the efficiency of various methods used for SCI subjects in this regard based on the available literature. METHODS: A search was done in some data bases such as Google scholar, ISI web of knowledge, PubMed, and Scopus. Some keywords such as bowel, bladder control and management were used in combination with SCI. The studies' quality was evaluated with Pedro scale. RESULTS: From 100 articles found, 21 papers were selected based on abstracts and titles. The quality of the studies varied between 5 and 7 based on Pedro scale. There were 3 studies on abdominal muscles stimulation, 1 on stimulation of tibial nerve, 8 on stimulation of sacral nerve root, 2 on combination of stimulation and exercise, 4 on Brindley bladder control and 3 on sacralizotomy. CONCLUSION: The bowel and bladder management functions is not the main problem of SCI subjects anymore. Some advantages of the mentioned procedures used for SCI subjects are including improved quality of life, socialization, and decreased bladder infection.

Nonlinear analysis of dynamic stability in walking with toe-only rocker sole shoes in elderly.

BACKGROUND: Elderly subjects are at the risk of falling. One type of shoe intervention used for this group of the subjects is the shoe with rocker. The aim of this study was to investigate the effects of shoes with various degrees of rockers on dynamic stability of elderly subjects while walking. METHOD: 15 elderly subjects were recruited in this study. A motion analysis system was used to record the motions of body while walking on a treadmill. The local dynamic stability (LDS) was evaluated based on use of Lyapunov exponent of center of mass (COM) movement. The subjects were asked to walk barefoot, with shoe with no rocker and with shoe with various rockers (10, 20, 30 and 40°). RESULTS: The mean values of LDS (λmax-S) in anteroposterior direction were 0.95 ± 0.46, 0.78 ± 0.51 and 0.74 ± 0.54 in bare foot, shoes with no rocker and shoe with 10° rocker, respectively. The mean value of LDS (λmax-S) in vertical direction varied between 1.21 and 1.23. There was no significant difference between LDS of elderly subjects while walking with shoes with various rocker angles. DISCUSSION: Use of shoes with various rocker angles dose not influence on dynamic stability of elderly subjects while walking. Therefore, it is recommended to use this kind of shoe intervention for other trapeutic purposes.

The Effects of Lower Limb Orthoses on Health Aspects of the Spinal Cord Injury Patients: A Systematic Review Using International Classification of Functioning, Disability, and Health (ICF) as a Reference Framework.

Background: One of the most important approaches in the rehabilitation of spinal cord injury (SCI) patients is the use of different orthoses. To date, no review has been published that analyzed the effects of orthoses on health aspects of spinal cord injury clients using the International Classification of Functioning, Disability and Health (ICF). Methods: A systematic literature search was done in some databases, including Medline, PubMed, Cochrane centered register of the controlled trial (CCTR), Cochrane database of systematic reviews (CDSR), a database of abstracts of reviews of effects (DARE), Embase, Google Scholar, and ISI Web of Knowledge. SCI was used in conjunction with terms like orthotic device, mechanical orthoses, external power orthoses, assistive devices, and functional electrical. The time frame for this search was from 1970 to 2022. Results: A total of 200 papers were found. Based on the titles and abstracts, 100 related papers were detected. After careful evaluation of the papers, 47 studies were selected for final analysis-53 papers were excluded due to duplication, non-English language, and lack of full-text. Conclusion: The results of 32 studies (70% of studies) support the efficiency of orthoses in walking and standing of SCI patients. In most of the included studies, the efficiency of orthoses was evaluated mostly based on body functions and structures, and their impact on other outcomes such as participation and quality of life (QoL) of SCI patients was unclear.