Publications by authors named "Ugo Della Croce"

61 Publications

Motor-Cognitive Treadmill Training With Virtual Reality in Parkinson's Disease: The Effect of Training Duration.

Front Aging Neurosci 2021 5;13:753381. Epub 2022 Jan 5.

IRCCS Ospedale Policlinico San Martino, Genova, Italy.

Treadmill training with virtual reality (TT + VR) has been shown to improve gait performance and to reduce fall risk in Parkinson's disease (PD). However, there is no consensus on the optimal training duration. This study is a sub-study of the V-TIME randomized clinical trial (NCT01732653). In this study, we explored the effect of the duration of training based on the motor-cognitive interaction on motor and cognitive performance and on fall risk in subjects with PD. Patients in Hoehn and Yahr stages II-III, aged between 40 and 70 years, were included. In total, 96 patients with PD were assigned to 6 or 12 weeks of TT + VR intervention, and 77 patients completed the full protocol. Outcome measures for gait and cognitive performance were assessed at baseline, immediately after training, and at 1- and 6-month follow-up. The incident rate of falls in the 6-month pre-intervention was compared with that in the 6-month post-intervention. Dual-task gait performance (gait speed, gait speed variability and stride length under cognitive dual task and obstacle negotiation, and the leading foot clearance in obstacle negotiation) improved similarly in both groups with gains sustained at 6-month follow-up. A higher decrease in fall rate and fear of falling were observed in participants assigned to the 12-week intervention than the 6-week intervention. Improvements in cognitive functions (i.e., executive functions, visuospatial ability, and attention) were seen only in participants enrolled in 12-week training up to 1-month follow-up but vanished at the 6-month evaluation. Our results suggest that a longer TT + VR training leads to greater improvements in cognitive functions especially those directly addressed by the virtual environment.
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http://dx.doi.org/10.3389/fnagi.2021.753381DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8767105PMC
January 2022

Extension of the Rigid-Constraint Method for the Heuristic Suboptimal Parameter Tuning to Ten Sensor Fusion Algorithms Using Inertial and Magnetic Sensing.

Sensors (Basel) 2021 Sep 21;21(18). Epub 2021 Sep 21.

Department of Electronics and Telecommunications, Politecnico di Torino, 10129 Torino, Italy.

The orientation of a magneto-inertial measurement unit can be estimated using a sensor fusion algorithm (SFA). However, orientation accuracy is greatly affected by the choice of the SFA parameter values which represents one of the most critical steps. A commonly adopted approach is to fine-tune parameter values to minimize the difference between estimated and true orientation. However, this can only be implemented within the laboratory setting by requiring the use of a concurrent gold-standard technology. To overcome this limitation, a Rigid-Constraint Method (RCM) was proposed to estimate suboptimal parameter values without relying on any orientation reference. The RCM method effectiveness was successfully tested on a single-parameter SFA, with an average error increase with respect to the optimal of 1.5 deg. In this work, the applicability of the RCM was evaluated on 10 popular SFAs with multiple parameters under different experimental scenarios. The average residual between the optimal and suboptimal errors amounted to 0.6 deg with a maximum of 3.7 deg. These encouraging results suggest the possibility to properly tune a generic SFA on different scenarios without using any reference. The synchronized dataset also including the optical data and the SFA codes are available online.
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http://dx.doi.org/10.3390/s21186307DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8473403PMC
September 2021

The Accuracy and Precision of Gait Spatio-Temporal Parameters Extracted from an Instrumented Sock during Treadmill and Overground Walking in Healthy Subjects and Patients with a Foot Impairment Secondary to Psoriatic Arthritis.

Sensors (Basel) 2021 Sep 15;21(18). Epub 2021 Sep 15.

Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada.

The objectives of this study were to assess the accuracy and precision of a system combining an IMU-instrumented sock and a validated algorithm for the estimation of the spatio-temporal parameters of gait. A total of 25 healthy participants (HP) and 21 patients with foot impairments secondary to psoriatic arthritis (PsA) performed treadmill walking at three different speeds and overground walking at a comfortable speed. HP performed the assessment over two sessions. The proposed system's estimations of cadence (CAD), gait cycle duration (GCD), gait speed (GS), and stride length (SL) obtained for treadmill walking were validated versus those estimated with a motion capture system. The system was also compared with a well-established multi-IMU-based system for treadmill and overground walking. The results showed a good agreement between the motion capture system and the IMU-instrumented sock in estimating the spatio-temporal parameters during the treadmill walking at normal and fast speeds for both HP and PsA participants. The accuracy of GS and SL obtained from the IMU-instrumented sock was better compared to the established multi-IMU-based system in both groups. The precision (inter-session reliability) of the gait parameter estimations obtained from the IMU-instrumented sock was good to excellent for overground walking and treadmill walking at fast speeds, but moderate-to-good for slow and normal treadmill walking. The proposed IMU-instrumented sock offers a novel form factor addressing the wearability issues of IMUs and could potentially be used to measure spatio-temporal parameters under clinical conditions and free-living conditions.
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http://dx.doi.org/10.3390/s21186179DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8472002PMC
September 2021

Detecting Sensitive Mobility Features for Parkinson's Disease Stages Via Machine Learning.

Mov Disord 2021 09 6;36(9):2144-2155. Epub 2021 May 6.

Laboratory for Early Markers Of Neurodegeneration (LEMON), Center for the Study of Movement, Cognition and Mobility, Neurological Institute, Tel Aviv Medical Center, Tel Aviv, Israel.

Background: It is not clear how specific gait measures reflect disease severity across the disease spectrum in Parkinson's disease (PD).

Objective: To identify the gait and mobility measures that are most sensitive and reflective of PD motor stages and determine the optimal sensor location in each disease stage.

Methods: Cross-sectional wearable-sensor records were collected in 332 patients with PD (Hoehn and Yahr scale I-III) and 100 age-matched healthy controls. Sensors were adhered to the participant's lower back, bilateral ankles, and wrists. Study participants walked in a ~15-meter corridor for 1 minute under two walking conditions: (1) preferred, usual walking speed and (2) walking while engaging in a cognitive task (dual-task). A subgroup (n = 303, 67% PD) also performed the Timed Up and Go test. Multiple machine-learning feature selection and classification algorithms were applied to discriminate between controls and PD and between the different PD severity stages.

Results: High discriminatory values were found between motor disease stages with mean sensitivity in the range 72%-83%, specificity 69%-80%, and area under the curve (AUC) 0.76-0.90. Measures from upper-limb sensors best discriminated controls from early PD, turning measures obtained from the trunk sensor were prominent in mid-stage PD, and stride timing and regularity were discriminative in more advanced stages.

Conclusions: Applying machine-learning to multiple, wearable-derived features reveals that different measures of gait and mobility are associated with and discriminate distinct stages of PD. These disparate feature sets can augment the objective monitoring of disease progression and may be useful for cohort selection and power analyses in clinical trials of PD. © 2021 International Parkinson and Movement Disorder Society.
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http://dx.doi.org/10.1002/mds.28631DOI Listing
September 2021

Analysis of the Accuracy of Ten Algorithms for Orientation Estimation Using Inertial and Magnetic Sensing under Optimal Conditions: One Size Does Not Fit All.

Sensors (Basel) 2021 Apr 5;21(7). Epub 2021 Apr 5.

PolitoBIOMed Lab-Biomedical Engineering Lab and Department of Electronics and Telecommunications, Politecnico di Torino, 10129 Torino, Italy.

The orientation of a magneto and inertial measurement unit (MIMU) is estimated by means of sensor fusion algorithms (SFAs) thus enabling human motion tracking. However, despite several SFAs implementations proposed over the last decades, there is still a lack of consensus about the best performing SFAs and their accuracy. As suggested by recent literature, the filter parameters play a central role in determining the orientation errors. The aim of this work is to analyze the accuracy of ten SFAs while running under the best possible conditions (i.e., their parameter values are set using the orientation reference) in nine experimental scenarios including three rotation rates and three commercial products. The main finding is that parameter values must be specific for each SFA according to the experimental scenario to avoid errors comparable to those obtained when the default parameter values are used. Overall, when optimally tuned, no statistically significant differences are observed among the different SFAs in all tested experimental scenarios and the absolute errors are included between 3.8 deg and 7.1 deg. Increasing the rotation rate generally leads to a significant performance worsening. Errors are also influenced by the MIMU commercial model. SFA MATLAB implementations have been made available online.
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http://dx.doi.org/10.3390/s21072543DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8038545PMC
April 2021

A Survey on the Use and Barriers of Surface Electromyography in Neurorehabilitation.

Front Neurol 2020 2;11:573616. Epub 2020 Oct 2.

Department of Biomedical Sciences, University of Sassari, Sassari, Italy.

Historical, educational, and technical barriers have been reported to limit the use of surface electromyography (sEMG) in clinical neurorehabilitation settings. In an attempt to identify, review, rank, and interpret potential factors that may play a role in this scenario, we gathered information on (1) current use of sEMG and its clinical potential; (2) professional figures primarily dealing with sEMG; (3) educational aspects, and (4) possible barriers and reasons for its apparently limited use in neurorehabilitation. To this aim, an online 30-question survey was sent to 52 experts on sEMG from diverse standpoints, backgrounds, and countries. Participants were asked to respond to each question on a 5-point Likert scale or by ranking items. A cut-off of 75% agreement was chosen as the consensus threshold. Thirty-five invitees (67%) completed the electronic survey. Consensus was reached for 77% of the proposed questions encompassing current trends in sEMG use in neurorehabilitation, educational, technical, and methodological features as well as its translational utility for clinicians and patients. Data evidenced the clinical utility of sEMG for patient assessment, to define the intervention plan, and to complement/optimize other methods used to quantify muscle and physical function. The aggregate opinion of the interviewed experts confirmed that sEMG is more frequently employed in technical/methodological than clinical research. Moreover, the slow dissemination of research findings and the lack of education on sEMG seem to prevent prompt transfer into practice. The findings of the present survey may contribute to the ongoing debate on the appropriateness and value of sEMG for neurorehabilitation professionals and its potential translation into clinical settings.
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http://dx.doi.org/10.3389/fneur.2020.573616DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7566898PMC
October 2020

Visuomotor Integration for Coupled Hand Movements in Healthy Subjects and Patients With Stroke.

Front Bioeng Biotechnol 2020 30;8:591. Epub 2020 Jun 30.

Department of Biomedical Sciences, University of Sassari, Sassari, Italy.

Many studies have investigated the bilateral upper limb coordination during movements under different motor and visual conditions. Bilateral training has also been proposed as an effective rehabilitative protocol for patients with stroke. However, the factors influencing in-phase vs. anti-phase coupling have not yet been fully explored. In this study, we used a motion capture device based on two infrared distance sensors to assess whether the up and down oscillation of the less functional hand (the non-dominant one in healthy younger and older subjects and the paretic one in patients with stroke) could be influenced by in-phase or anti-phase coupling of the more functional hand and by visual feedback. Similar patterns were found between single hand movements and in-phase coupled movements, whereas anti-phase coupled movements were less ample, less sinusoidal, but more frequent. These features were particularly evident for patients with stroke who showed a reduced waveform similarity of bilateral movements in all conditions but especially for anti-phase movements under visual control. These results indicate that visuomotor integration in patients with stroke could be less effective than in healthy subjects, probably because of the attentional overload required when moving the two limbs in an alternating fashion.
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http://dx.doi.org/10.3389/fbioe.2020.00591DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7339959PMC
June 2020

Do Patients With Parkinson's Disease With Freezing of Gait Respond Differently Than Those Without to Treadmill Training Augmented by Virtual Reality?

Neurorehabil Neural Repair 2020 05 23;34(5):440-449. Epub 2020 Mar 23.

KU Leuven, Leuven, Belgium.

. People with Parkinson's disease and freezing of gait (FOG+) have more falls, postural instability and cognitive impairment compared with FOG-. . To conduct a secondary analysis of the V-TIME study, a randomized, controlled investigation showing a greater reduction of falls after virtual reality treadmill training (TT + VR) compared with usual treadmill walking (TT) in a mixed population of fallers. We addressed whether these treadmill interventions led to similar gains in FOG+ as in FOG-. . A total of 77 FOG+ and 44 FOG- were assigned randomly to TT + VR or TT. Participants were assessed pre- and posttraining and at 6 months' follow-up. Main outcome was postural stability assessed by the Mini Balance Evaluation System Test (Mini-BEST) test. Falls were documented using diaries. Other outcomes included the New Freezing of Gait Questionnaire (NFOG-Q) and the Trail Making Test (TMT-B). . Mini-BEST scores and the TMT-B improved in both groups after training ( = .001), irrespective of study arm and FOG subgroup. However, gains were not retained at 6 months. Both FOG+ and FOG- had a greater reduction of falls after TT + VR compared with TT ( = .008). NFOG-Q scores did not change after both training modes in the FOG+ group. . Treadmill walking (with or without VR) improved postural instability in both FOG+ and FOG-, while controlling for disease severity differences. As found previously, TT + VR reduced falls more than TT alone, even among those with FOG. Interestingly, FOG itself was not helped by training, suggesting that although postural instability, falls and FOG are related, they may be controlled by different mechanisms.
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http://dx.doi.org/10.1177/1545968320912756DOI Listing
May 2020

A Canine Gait Analysis Protocol for Back Movement Assessment in German Shepherd Dogs.

Vet Sci 2020 Feb 19;7(1). Epub 2020 Feb 19.

Veterinary Department, University of Sassari, 07100 Sassari, Italy.

Objective-To design and test a motion analysis protocol for the gait analysis of adult German Shepherd (GS) dogs with a focus in the analyses of their back movements. Animals-Eight clinically healthy adult large-sized GS dogs (age, 4 ± 1.3 years; weight, 38.8 ± 4.2 kg). Procedures-A six-camera stereo-photogrammetric system and two force platforms were used for data acquisition. Experimental acquisition sessions consisted of static and gait trials. During gait trials, each dog walked along a 6 m long walkway at self-selected speed and a total of six gait cycles were recorded. Results-Grand mean and standard deviation of ground reaction forces of fore and hind limbs are reported. Spatial-temporal parameters averaged over gait cycles and subjects, their mean, standard deviation and coefficient of variance are analyzed. Joint kinematics for the hip, stifle and tarsal joints and their average range of motion (ROM) values, and their 95% Confidence Interval (CI) values of kinematics curves are reported. Conclusions and Clinical Relevance-This study provides normative data of healthy GS dogs to form a preliminary basis in the analysis of the spatial-temporal parameters, kinematics and kinetics during quadrupedal stance posture and gait. Also, a new back movement protocol enabling a multi-segment back model is provided. Results show that the proposed gait analysis protocol may become a useful and objective tool for the evaluation of canine treatment with special focus on the back movement.
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http://dx.doi.org/10.3390/vetsci7010026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7158696PMC
February 2020

Falls Risk in Relation to Activity Exposure in High-Risk Older Adults.

J Gerontol A Biol Sci Med Sci 2020 05;75(6):1198-1205

Translational and Clinical Research Institute, Faculty of Medical Sciences, Clinical Ageing Research Unit, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, UK.

Background: Physical activity is linked to many positive health outcomes, stimulating the development of exercise programs. However, many falls occur while walking and so promoting activity might paradoxically increase fall rates, causing injuries, and worse quality of life. The relationship between activity exposure and fall rates remains unclear. We investigated the relationship between walking activity (exposure to risk) and fall rates before and after an exercise program (V-TIME).

Methods: One hundred and nine older fallers, 38 fallers with mild cognitive impairment (MCI), and 128 fallers with Parkinson's disease (PD) were randomly assigned to one of two active interventions: treadmill training only or treadmill training combined with a virtual reality component. Participants were tested before and after the interventions. Free-living walking activity was characterized by volume, pattern, and variability of ambulatory bouts using an accelerometer positioned on the lower back for 1 week. To evaluate that relationship between fall risk and activity, a normalized index was determined expressing fall rates relative to activity exposure (FRA index), with higher scores indicating a higher risk of falls per steps taken.

Results: At baseline, the FRA index was higher for fallers with PD compared to those with MCI and older fallers. Walking activity did not change after the intervention for the groups but the FRA index decreased significantly for all groups (p ≤ .035).

Conclusions: This work showed that V-TIME interventions reduced falls risk without concurrent change in walking activity. We recommend using the FRA index in future fall prevention studies to better understand the nature of intervention programs.
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http://dx.doi.org/10.1093/gerona/glaa007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7243591PMC
May 2020

Objective measures to investigate turning impairments and freezing of gait in people with Parkinson's disease.

Gait Posture 2019 10 5;74:187-193. Epub 2019 Sep 5.

Department of Neurology, Oregon Health & Science University, Portland, OR, United States.

Background: Turning is impaired in people with Parkinson's Disease (PD) and it is a common trigger for freezing of gait (FoG). Recent evidence suggests that people with PD who freeze (PD+FoG) have worse turning performance than those who don't have freezing (non-freezers, PD-FoG), and the freezing episodes are exacerbated by increasing the turn angular amplitude.

Research Question: We investigated the difference between turning 180° while walking versus turning 360° in place, in both single- and dual-task conditions, by means of objective measures in people with PD with and without FoG.

Methods: Twenty-four PD+FoG and eighteen PD-FoG performed 180° turns while walking and 360° turns in place during single- and dual-task conditions. Quantitative measures of turning and the dual-task cost were computed. Differences were investigated between groups and within turning types using ANOVA. Associations between turn measures and clinical scales were examined with Spearman correlations.

Results: Turn duration and the number of steps were greater, and peak angular velocity slower, in PD+FoG compared to PD-FoG (p < 0.001). Dual-task costs were similar across groups, but turn duration showed significant interaction (p = 0.03). Posture Instability and Gait Disability (PIGD) subscore was associated with all turn measures in PD-FoG; whereas PIGD was mainly associated with turning while walking in PD+FoG.

Significance: Objective measures of turning revealed differences between people with and without FoG, specifically, people with FoG showed more impairments in 360° turning in place compared to 180° turning while walking. However, as the turning challenges were increased by adding a dual-task, results from PD+FoG were similar to those from PD-FoG.
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http://dx.doi.org/10.1016/j.gaitpost.2019.09.001DOI Listing
October 2019

Isokinetic predictors of gait speed increase following high-intensity resistance training of the ankle dorsiflexors in people with multiple sclerosis: A pilot study.

Clin Biomech (Bristol, Avon) 2019 07 9;67:102-106. Epub 2019 May 9.

Department of Biomedical Sciences, University of Sassari, Sassari, Italy. Electronic address:

Background: Maximal strength is a predictor of functional capacity for people with multiple sclerosis (PwMS), who frequently exhibit unilateral weakness of the ankle dorsiflexors. Aims of this study were to investigate the relationships between dorsiflexors' weakness and gait speed, the effects of high-intensity training of the affected dorsiflexors on gait performance and to identify isokinetic predictors of changes in gait speed in PwMs.

Methods: Twenty patients aged 45 (10.3) years, illness duration 14.9 (8.5) years, median EDSS 3, underwent isokinetic dorsiflexors' strength testing at 10°/s and 45°/s angular velocities and gait analysis before and after a 6-week training of dorsiflexors. Pre-to-post differences in strength and gait parameters were analyzed by paired t-test; association between gait speed and isokinetic parameters was tested through correlation and regression analyses.

Findings: Dorsiflexors' strength (peak moment at 10°/s: +14.9%, p = 0.02; at 45°/s: +21.7%, p = 0.03) and gait parameters (speed: +9.6%; p = 0.004; stride time: -5.7%; p = 0.01; cadence: +6.2%; p = 0.001; ankle power: +27.5%, p = 0.003) increased significantly. Of the thirteen isokinetic descriptors of strength, only peak moment, maximal and total work significantly correlated with gait speed increase. Regression analyses revealed high beta coefficients only for maximal work (10°/s: B = -6.528; beta = -1.825; p = 0.008; 45°/s: B = -1.466; beta = -1.364; p = 0.03).

Interpretation: In PwMS, high-intensity training of weakened ankle dorsiflexors induced significant improvements in maximal strength and gait speed. The finding of maximal work as a significant predictor of training-induced changes in gait speed suggests that PwMS with reduced muscle work may benefit from strength training approaches aimed at increasing gait speed. Registration number: ClinicalTrials.gov Identifier: NCT02010398.
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http://dx.doi.org/10.1016/j.clinbiomech.2019.05.008DOI Listing
July 2019

Is every-day walking in older adults more analogous to dual-task walking or to usual walking? Elucidating the gaps between gait performance in the lab and during 24/7 monitoring.

Eur Rev Aging Phys Act 2019 3;16. Epub 2019 May 3.

1Center for the Study of Movement, Cognition and Mobility, Neurological Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.

Background: The traditional evaluation of gait in the laboratory during structured testing has provided important insights, but is limited by its "snapshot" character and observation in an unnatural environment. Wearables enable monitoring of gait in real-world environments over a week. Initial findings show that in-lab and real-world measures differ. As a step towards better understanding these gaps, we directly compared in-lab usual-walking (UW) and dual-task walking (DTW) to daily-living measures of gait.

Methods: In-lab gait features (e.g., gait speed, step regularity, and stride regularity) derived from UW and DTW were compared to the same gait features during daily-living in 150 elderly fallers (age: 76.5 ± 6.3 years, 37.6% men). In both settings, features were extracted from a lower-back accelerometer. In the real-world setting, subjects were asked to wear the device for 1 week and pre-processing detected 30-s daily-living walking bouts. A histogram of all walking bouts was determined for each walking feature for each subject and then each subject's typical (percentile 50, median), worst (percentile 10) and the best (percentile 90) values over the week were determined for each feature. Statistics of reliability were assessed using Intra-Class correlations and Bland-Altman plots.

Results: As expected, in-lab gait speed, step regularity, and stride regularity were worse during DTW, compared to UW. In-lab gait speed, step regularity, and stride regularity during UW were significantly higher (i.e., better) than the typical daily-living values ( < 0.001) and different ( < 0.001) from the worst and best values. DTW values tended to be similar to typical daily-living values ( = 0.205,  = 0.053,  = 0.013 respectively). ICC assessment and Bland-Altman plots indicated that in-lab values do not reliably reflect the daily-walking values.

Conclusions: Gait values measured during relatively long (30-s) daily-living walking bouts are more similar to the corresponding values obtained in the lab during dual-task walking, as compared to usual walking. Still, gait performance during most daily-living walking bouts is worse than that measured during usual and dual-tasking in the lab. The values measured in the lab do not reliably reflect daily-living measures. That is, an older adult's typical daily-living gait cannot be estimated by simply measuring walking in a structured, laboratory setting.
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http://dx.doi.org/10.1186/s11556-019-0214-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6498572PMC
May 2019

Associations between daily-living physical activity and laboratory-based assessments of motor severity in patients with falls and Parkinson's disease.

Parkinsonism Relat Disord 2019 05 29;62:85-90. Epub 2019 Jan 29.

Center for the study of Movement, Cognition and Mobility, Neurological Institute, Tel Aviv Sourasky Medical Center, Israel; Department of Physical Therapy, Sackler Faculty of Medicine, Israel; Sagol School of Neuroscience, Tel Aviv University, Israel; Rush Alzheimer's Disease Center and Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, USA. Electronic address:

Introduction: Recent work suggests that wearables can augment conventional measures of Parkinson's disease (PD). We evaluated the relationship between conventional measures of disease and motor severity (e.g., MDS-UPDRS part III), laboratory-based measures of gait and balance, and daily-living physical activity measures in patients with PD.

Methods: Data from 125 patients (age: 71.7 ± 6.5 years, Hoehn and Yahr: 1-3, 60.5% men) were analyzed. The MDS-UPDRS-part III was used as the gold standard of motor symptom severity. Gait and balance were quantified in the laboratory. Daily-living gait and physical activity metrics were extracted from an accelerometer worn on the lower back for 7 days.

Results: In multivariate analyses, daily-living physical activity and gait metrics, laboratory-based balance, demographics and subject characteristics together explained 46% of the variance in MDS-UPDRS-part III scores. Daily-living measures accounted for 62% of the explained variance, laboratory measures 30%, and demographics and subject characteristics 7% of the explained variance. Conversely, demographics and subject characteristics, laboratory-based measures of gait symmetry, and motor symptom severity together explained less than 30% of the variance in total daily-living physical activity. MDS-UPDRS-part III scores accounted for 13% of the explained variance, i.e., <4% of all the variance in total daily-living activity.

Conclusions: Our findings suggest that conventional measures of motor symptom severity do not strongly reflect daily-living activity and that daily-living measures apparently provide important information that is not captured in a conventional one-time, laboratory assessment of gait, balance or the MDS-UPDRS. To provide a more complete evaluation, wearable devices should be considered.
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http://dx.doi.org/10.1016/j.parkreldis.2019.01.022DOI Listing
May 2019

A wearable solution for accurate step detection based on the direct measurement of the inter-foot distance.

J Biomech 2019 02 31;84:274-277. Epub 2018 Dec 31.

Department of Biomedical Sciences, Bioengineering Unit, University of Sassari, Sassari (SS), Italy.

Accurate step detection is crucial for the estimation of gait spatio-temporal parameters. Although several step detection methods based on the use of inertial measurement units (IMUs) have been successfully proposed, they may not perform adequately when the foot is dragged while walking, when walking aids are used, or when walking at low speed. The aim of this study was to test an original step-detection method, the inter-foot distance step counter (IFOD), based on the direct measurement of the distance between feet. Gait data were recorded using a wearable prototype system (SWING), which integrates an IMU and two time-of-flight distance sensors (DSs). The system was attached to the medial side of the right foot with one DS positioned close to the forefoot (FORE) and the other close to the rearfoot (REAR). Sixteen healthy adults were asked to walk over ground for two minutes along a loop, including both rectilinear and curvilinear portions, during two experimental sessions. The accuracy of the IFOD step counter was assessed using a stereo-photogrammetric system as gold standard. The best performance was obtained for REAR with an accuracy higher than 99.8% for the instrumented foot step and 88.8% for the non-instrumented foot step during both rectilinear and curvilinear walks. Key features of the IFOD step counter are that it is possible to detect both right and left steps by instrumenting one foot only and that it does not rely on foot impact dynamics. The IFOD step counter can be combined with existing IMU-based methods for increasing step-detection accuracy.
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http://dx.doi.org/10.1016/j.jbiomech.2018.12.039DOI Listing
February 2019

Sardinian Folk Dance for Individuals with Parkinson's Disease: A Randomized Controlled Pilot Trial.

J Altern Complement Med 2019 Mar 9;25(3):305-316. Epub 2019 Jan 9.

1 Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy.

Objectives: Among different exercise models proposed for individuals with Parkinson's disease (IwPD), the popularity of traditional forms of dance is increasing. The aim of this study was to evaluate the effects of Sardinian folk dance (Ballu Sardu, BS) on functional performance and motor and nonmotor symptoms in IwPD.

Design: Single-blind, randomized controlled pilot trial.

Settings: Outpatient health clinic.

Subjects And Interventions: Twenty IwPD (13M, 7F; 67.4 ± 6.1 years) were randomly assigned to BS (n = 10) or usual care (n = 10). The dance program consisted of two sessions/week, 90-min/class, for 12 weeks.

Outcome Measures: Motor and nonmotor symptoms, as well as functional performance, were evaluated using different questionnaires and tests such as the Unified Parkinson's Disease Rating Scale Part-III (UPDRS-III), 6-min walking test (6MWT), Berg Balance Scale (BBS), Timed Up-and-Go (TUG) test, Five Times Sit-to-Stand Test (FTSST), Back Scratch Test (BST), Sit-and-Reach Test (SRT), instrumented gait analysis, Parkinson's Disease Fatigue Scale (PFS-16), Beck Depression Inventory, Starkstein Apathy Scale (SAS), and Montreal Cognitive Assessment (MOCA) scale.

Results: Repeated-measures analysis of variance revealed significant Time × Group interactions for UPDRS-III and functional variables such as the 6MWT, BBS, FTSST, TUG (all, p < 0.001), BST (p = 0.04), and gait analysis parameters (stride length, p = 0.031; gait speed, p = 0.049; and gait fatigue index (GFI), p = 0.005). For nonmotor symptoms, significant Time × Group interactions for depression (p < 0.001), apathy (p = 0.016), and MOCA scores (p = 0.012) were observed. Of note, for GFI and SAS, the BS group only showed a trend toward improvement, while the condition of the controls worsened significantly. No between-group differences were observed for SRT and PFS-16.

Conclusions: BS is an enjoyable activity, which has been proved to be superior to usual care alone in inducing changes in different motor and nonmotor symptoms associated with PD. Results show that BS can be considered a safe tool for contrasting impairments observed in IwPD due to the intrinsic nature of the neurodegenerative disease.
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http://dx.doi.org/10.1089/acm.2018.0413DOI Listing
March 2019

Knee joint sagittal plane movement in cerebral palsy: a comparative study of 2-dimensional markerless video and 3-dimensional gait analysis.

Acta Orthop 2018 Dec;89(6):656-661

f Department of Orthopedics , Skaraborg Hospital Skövde and Mölndal Hospital Sahlgrenska , Gothenburg , Sweden.

Background and purpose - Gait analysis is indicated in children with cerebral palsy (CP) to identify and quantify gait deviations. One particularly difficult-to-treat deviation, crouch gait, can progress in adolescence and ultimately limit the ability to ambulate. An objective quantitative assessment is essential to early identify progressive gait impairments in children with CP. 3-dimensional gait analysis (3D GA) is considered the gold standard, although it is expensive, seldom available, and unnecessarily detailed for screening and follow-up. Simple video assessments are time-consuming when processed manually, but more convenient if used in conjunction with video processing algorithms; this has yet been validated in CP. We validate a 2-dimensional markerless (2D ML) assessment of knee joint flexion/extension angles of the gait cycle in children and young adults with CP. Patients and methods - 18 individuals, mean age 15 years (6.5-28), participated. 11 had bilateral, 3 unilateral, 3 dyskinetic, and 1 ataxic CP. In the Gross Motor Function Classification System, 6 were at level I, 11 at level II, and 1 at level III. We compared 2D ML, using a single video camera with computer processing, and 3D GA. Results - The 2D ML method overestimated the knee flexion/extension angle values by 3.3 to 7.0 degrees compared with 3D GA. The reliability within 2D ML and 3D GA was mostly good to excellent. Interpretation - Despite overestimating, 2D ML is a reliable and convenient tool to assess knee angles and, more importantly, to detect changes over time within a follow-up program in ambulatory children with CP.
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http://dx.doi.org/10.1080/17453674.2018.1525195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6300740PMC
December 2018

Estimation of spatio-temporal parameters of gait from magneto-inertial measurement units: multicenter validation among Parkinson, mildly cognitively impaired and healthy older adults.

Biomed Eng Online 2018 May 9;17(1):58. Epub 2018 May 9.

Department of Biomedical Sciences, University of Sassari, Sassari, Italy.

Background: The use of miniaturized magneto-inertial measurement units (MIMUs) allows for an objective evaluation of gait and a quantitative assessment of clinical outcomes. Spatial and temporal parameters are generally recognized as key metrics for characterizing gait. Although several methods for their estimate have been proposed, a thorough error analysis across different pathologies, multiple clinical centers and on large sample size is still missing. The aim of this study was to apply a previously presented method for the estimate of spatio-temporal parameters, named Trusted Events and Acceleration Direct and Reverse Integration along the direction of Progression (TEADRIP), on a large cohort (236 patients) including Parkinson, mildly cognitively impaired and healthy older adults collected in four clinical centers. Data were collected during straight-line gait, at normal and fast walking speed, by attaching two MIMUs just above the ankles. The parameters stride, step, stance and swing durations, as well as stride length and gait velocity, were estimated for each gait cycle. The TEADRIP performance was validated against data from an instrumented mat.

Results: Limits of agreements computed between the TEADRIP estimates and the reference values from the instrumented mat were - 27 to 27 ms for Stride Time, - 68 to 44 ms for Stance Time, - 31 to 31 ms for Step Time and - 67 to 52 mm for Stride Length. For each clinical center, the mean absolute errors averaged across subjects for the estimation of temporal parameters ranged between 1 and 4%, being on average less than 3% (< 30 ms). Stride length mean absolute errors were on average 2% (≈ 25 mm). Error comparisons across centers did not show any significant difference. Significant error differences were found exclusively for stride and step durations between healthy elderly and Parkinsonian subjects, and for the stride length between walking speeds.

Conclusions: The TEADRIP method was effectively validated on a large number of healthy and pathological subjects recorded in four different clinical centers. Results showed that the spatio-temporal parameters estimation errors were consistent with those previously found on smaller population samples in a single center. The combination of robustness and range of applicability suggests the use of the TEADRIP as a suitable MIMU-based method for gait spatio-temporal parameter estimate in the routine clinical use. The present paper was awarded the "SIAMOC Best Methodological Paper 2017".
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http://dx.doi.org/10.1186/s12938-018-0488-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5941594PMC
May 2018

SIAMOC position paper on gait analysis in clinical practice: General requirements, methods and appropriateness. Results of an Italian consensus conference.

Gait Posture 2017 10 5;58:252-260. Epub 2017 Aug 5.

Azienda Sanitaria Universitaria Integrata di Udine, Italy.

Gait analysis is recognized as a useful assessment tool in the field of human movement research. However, doubts remain on its real effectiveness as a clinical tool, i.e. on its capability to change the diagnostic-therapeutic practice. In particular, the conditions in which evidence of a favorable cost-benefit ratio is found and the methodology for properly conducting and interpreting the exam are not identified clearly. To provide guidelines for the use of Gait Analysis in the context of rehabilitation medicine, SIAMOC (the Italian Society of Clinical Movement Analysis) promoted a National Consensus Conference which was held in Bologna on September 14th, 2013. The resulting recommendations were the result of a three-stage process entailing i) the preparation of working documents on specific open issues, ii) the holding of the consensus meeting, and iii) the drafting of consensus statements by an external Jury. The statements were formulated based on scientific evidence or experts' opinion, when the quality/quantity of the relevant literature was deemed insufficient. The aim of this work is to disseminate the consensus statements. These are divided into 13 questions grouped in three areas of interest: 1) General requirements and management, 2) Methodological and instrumental issues, and 3) Scientific evidence and clinical appropriateness. SIAMOC hopes that this document will contribute to improve clinical practice and help promoting further research in the field.
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http://dx.doi.org/10.1016/j.gaitpost.2017.08.003DOI Listing
October 2017

Static and Dynamic Accuracy of an Innovative Miniaturized Wearable Platform for Short Range Distance Measurements for Human Movement Applications.

Sensors (Basel) 2017 Jun 24;17(7). Epub 2017 Jun 24.

Information Engineering Unit, Department of Information Engineering, Political Sciences and Communication Sciences, University of Sassari, Sassari 07100 (SS), Italy.

Magneto-inertial measurement units (MIMU) are a suitable solution to assess human motor performance both indoors and outdoors. However, relevant quantities such as step width and base of support, which play an important role in gait stability, cannot be directly measured using MIMU alone. To overcome this limitation, we developed a wearable platform specifically designed for human movement analysis applications, which integrates a MIMU and an Infrared Time-of-Flight proximity sensor (IR-ToF), allowing for the estimate of inter-object distance. We proposed a thorough testing protocol for evaluating the IR-ToF sensor performances under experimental conditions resembling those encountered during gait. In particular, we tested the sensor performance for different (i) target colors; (ii) sensor-target distances (up to 200 mm) and (iii) sensor-target angles of incidence (AoI) (up to 60 ∘ ). Both static and dynamic conditions were analyzed. A pendulum, simulating the oscillation of a human leg, was used to generate highly repeatable oscillations with a maximum angular velocity of 6 rad/s. Results showed that the IR-ToF proximity sensor was not sensitive to variations of both distance and target color (except for black). Conversely, a relationship between error magnitude and AoI values was found. For AoI equal to 0 ∘ , the IR-ToF sensor performed equally well both in static and dynamic acquisitions with a distance mean absolute error <1.5 mm. Errors increased up to 3.6 mm (static) and 11.9 mm (dynamic) for AoI equal to ± 30 ∘ , and up to 7.8 mm (static) and 25.6 mm (dynamic) for AoI equal to ± 60 ∘ . In addition, the wearable platform was used during a preliminary experiment for the estimation of the inter-foot distance on a single healthy subject while walking. In conclusion, the combination of magneto-inertial unit and IR-ToF technology represents a valuable alternative solution in terms of accuracy, sampling frequency, dimension and power consumption, compared to existing technologies.
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http://dx.doi.org/10.3390/s17071492DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5539655PMC
June 2017

Automatic classification of gait in children with early-onset ataxia or developmental coordination disorder and controls using inertial sensors.

Gait Posture 2017 02 2;52:287-292. Epub 2016 Dec 2.

The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy.

Early-Onset Ataxia (EOA) and Developmental Coordination Disorder (DCD) are two conditions that affect coordination in children. Phenotypic identification of impaired coordination plays an important role in their diagnosis. Gait is one of the tests included in rating scales that can be used to assess motor coordination. A practical problem is that the resemblance between EOA and DCD symptoms can hamper their diagnosis. In this study we employed inertial sensors and a supervised classifier to obtain an automatic classification of the condition of participants. Data from shank and waist mounted inertial measurement units were used to extract features during gait in children diagnosed with EOA or DCD and age-matched controls. We defined a set of features from the recorded signals and we obtained the optimal features for classification using a backward sequential approach. We correctly classified 80.0%, 85.7%, and 70.0% of the control, DCD and EOA children, respectively. Overall, the automatic classifier correctly classified 78.4% of the participants, which is slightly better than the phenotypic assessment of gait by two pediatric neurologists (73.0%). These results demonstrate that automatic classification employing signals from inertial sensors obtained during gait maybe used as a support tool in the differential diagnosis of EOA and DCD. Furthermore, future extension of the classifier's test domains may help to further improve the diagnostic accuracy of pediatric coordination impairment. In this sense, this study may provide a first step towards incorporating a clinically objective and viable biomarker for identification of EOA and DCD.
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http://dx.doi.org/10.1016/j.gaitpost.2016.12.002DOI Listing
February 2017

An innovative training program based on virtual reality and treadmill: effects on gait of persons with multiple sclerosis.

Disabil Rehabil 2017 07 3;39(15):1557-1563. Epub 2016 Nov 3.

d Laboratory for Gait Analysis & Neurodynamics, Movement Disorders Unit, Department of Neurology , Tel Aviv Sourasky Medical Center , Tel Aviv , Israel.

Aim: In this single blind randomized controlled trial, we examined the effect of a virtual reality-based training on gait of people with multiple sclerosis.

Methods: Twenty-five individuals with multiple sclerosis with mild to moderate disability were randomly assigned to either the control group (n = 11) or the experimental group (n = 14). The subjects in the control group received treadmill training. Subjects in the experimental group received virtual reality based treadmill training. Clinical measures and gait parameters were evaluated.

Result: Subjects in both the groups significantly improved the walking endurance and speed, cadence and stride length, lower limb joint ranges of motion and powers, during single and dual task gait. Moreover, subjects in the experimental group also improved balance, as indicated by the results of the clinical motor tests (p < 0.05). Between-group comparisons revealed that the experimental group improved significantly more than control group in hip range of motion and hip generated power at terminal stance at post-training.

Conclusion: Our results support the perceived benefits of training programs that incorporate virtual reality to improve gait measures in individuals with multiple sclerosis. Implication of rehabilitation Gait deficits are common in multiple sclerosis (85%) and worsen during dual task activities. Intensive and progressive treadmill training, with and without virtual reality, is effective on dual task gait in persons with multiple sclerosis. Virtual reality-based treadmill training requiring obstacle negotiation increases the range of motion and the power generated at the hip, consequently allowing longer stride length and, consequently, higher gait speed.
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http://dx.doi.org/10.1080/09638288.2016.1224935DOI Listing
July 2017

Effects of a virtual reality and treadmill training on gait of subjects with multiple sclerosis: a pilot study.

Mult Scler Relat Disord 2016 Jan 6;5:91-6. Epub 2015 Nov 6.

Department of Neurology, Laboratory for Gait Analysis & Neurodynamics, Movement Disorders Unit, Tel Aviv Sourasky Medical Center, 6 Weizmann Street, Tel Aviv, Israel; Sackler school of Medicine, Department of Neurology, Tel Aviv University, Tel Aviv, Israel.

Gait and cognitive deficits are common in multiple sclerosis (MS) and are negatively affected during dual-task walking. Treadmill (TM) training has been previously used to preserve locomotor activity in MS. Virtual reality (VR) engages the user in cognitive and motor activities simultaneously. A training combining TM and VR has been successfully adopted in several neurological diseases, but not in MS. This study aims at investigating the feasibility of a VR-based TM training program on gait of subjects with MS. Eight persons with relapsing-remitting MS were recruited to participate in a six-week VR-based TM training program. Gait analysis was performed both in single and dual task conditions. Clinical tests were used to assess walking endurance and obstacle negotiation. All the evaluations were performed before, immediately and one month after the training. Gait speed and stride length improved in dual task post-intervention and were retained at follow-up. An improved ability in negotiating obstacles was found across the evaluations. VR-based TM training program is feasible and safe for MS subjects with moderate disabilities and may positively affect gait under complex conditions, such as dual tasking and obstacle negotiation.
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http://dx.doi.org/10.1016/j.msard.2015.11.002DOI Listing
January 2016

Hidden Markov model-based strategy for gait segmentation using inertial sensors: Application to elderly, hemiparetic patients and Huntington's disease patients.

Annu Int Conf IEEE Eng Med Biol Soc 2015 ;2015:5179-82

A solution to discriminate stance and swing in both healthy and abnormal gait using inertial sensors is proposed. The method is based on a two states hidden Markov model trained in a supervised way. The proposed method can generalize across different groups of subjects, without the need of parameters tuning. Leave-one-subject-out validation tests showed 20 ms and 16 ms errors on average in the determination of foot strike and toe off events across the three groups of subjects including 10 elderly, 10 hemiparetic patients and 10 Huntington's disease patients. The proposed methodology can be implemented online in portable devices to be used in clinical practice or in everyday personal health assessment.
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http://dx.doi.org/10.1109/EMBC.2015.7319558DOI Listing
September 2016

Feasibility of an Exoskeleton-Based Interactive Video Game System for Upper Extremity Burn Contractures.

PM R 2016 05 25;8(5):445-52. Epub 2015 Sep 25.

Department of Physical Medicine & Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA(‖).

Background: Burn contractures are common and difficult to treat. Measuring continuous joint motion would inform the assessment of contracture interventions; however, it is not standard clinical practice. This study examines use of an interactive gaming system to measure continuous joint motion data.

Objective: To assess the usability of an exoskeleton-based interactive gaming system in the rehabilitation of upper extremity burn contractures.

Design: Feasibility study.

Setting: Eight subjects with a history of burn injury and upper extremity contractures were recruited from the outpatient clinic of a regional inpatient rehabilitation facility.

Methods: Subjects used an exoskeleton-based interactive gaming system to play 4 different video games. Continuous joint motion data were collected at the shoulder and elbow during game play.

Main Outcome Measures: Visual analog scale for engagement, difficulty and comfort. Angular range of motion by subject, joint, and game.

Results: The study population had an age of 43 ± 16 (mean ± standard deviation) years and total body surface area burned range of 10%-90%. Subjects reported satisfactory levels of enjoyment, comfort, and difficulty. Continuous joint motion data demonstrated variable characteristics by subject, plane of motion, and game.

Conclusions: This study demonstrates the feasibility of use of an exoskeleton-based interactive gaming system in the burn population. Future studies are needed that examine the efficacy of tailoring interactive video games to the specific joint impairments of burn survivors.
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http://dx.doi.org/10.1016/j.pmrj.2015.09.012DOI Listing
May 2016

A 2D Markerless Gait Analysis Methodology: Validation on Healthy Subjects.

Comput Math Methods Med 2015 30;2015:186780. Epub 2015 Apr 30.

Department of Information Engineering, Political Sciences and Communication Sciences, University of Sassari, 07100 Sassari, Italy ; Interuniversity Centre of Bioengineering of the Human Neuromusculoskeletal System, Sassari, Italy.

A 2D markerless technique is proposed to perform lower limb sagittal plane kinematic analysis using a single video camera. A subject-specific, multisegmental model of the lower limb was calibrated with the subject in an upright standing position. Ankle socks and underwear garments were used to track the feet and pelvis segments, whereas shank and thigh segments were tracked by means of reference points identified on the model. The method was validated against a marker based clinical gait model. The accuracy of the spatiotemporal parameters estimation was found suitable for clinical use (errors between 1% and 3% of the corresponding true values). Comparison analysis of the kinematics patterns obtained with the two systems revealed high correlation for all the joints (0.82 < R(2) < 0.99). Differences between the joint kinematics estimates ranged from 3.9 deg to 6.1 deg for the hip, from 2.7 deg to 4.4 deg for the knee, and from 3.0 deg to 4.7 deg for the ankle. The proposed technique allows a quantitative assessment of the lower limb motion in the sagittal plane, simplifying the experimental setup and reducing the cost with respect to traditional marker based gait analysis protocols.
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http://dx.doi.org/10.1155/2015/186780DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4430646PMC
April 2016

Bulk effect of the deltoid muscle on the glenohumeral joint.

J Exp Orthop 2014 Dec 4;1(1):14. Epub 2014 Nov 4.

Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Stoneman 10, Boston, 02215, MA, USA.

Background: There remains controversy on the role of the deltoid on glenohumeral translations during basic and pitching motions. We thus studied the passive effect of the deltoid on the deltoid glenohumeral joint center (GHJC).

Methods: Six shoulders were tested using an automated mechanical system. A baseline motion pattern of the intact specimen was contrasted with glenohumeral translation after removal of the deltoid. Each condition was evaluated in abduction (ABD) and an abbreviated throwing motion (ATM) using retro-reflective, bone-embedded markers. The absolute trajectory and the area under the curve (AUC) for each motion were calculated and glenohumeral kinematics with respect to the GH translation were compared.

Results: The removal of the deltoid resulted in significant changes of the GH translation. During 30-60° of ABD, it resulted in a superior and more anterior GH translation, while in the 60-90° segment in a more inferior and medial GH translation. During 90-120°, the GH translation was medialized. In the pitching motion from maximum external rotation to 90° of external rotation (ER), the removal of the deltoid resulted in a more superior, anterior and lateral GH translation. Thus limits anterior translation in the abduction-external rotation position. In the remaining segments (90-80° and 80-45° of ER), it resulted in a lateralization of the GH translation.

Conclusions: Modelling the throwing shoulder, the deltoid has a significant influence on glenohumeral motion. Athletes with deltoid dysfunction and limited range of motion are at risk for injury due to the resulting change in their throwing mechanics.
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http://dx.doi.org/10.1186/s40634-014-0014-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4546007PMC
December 2014

Estimation of step-by-step spatio-temporal parameters of normal and impaired gait using shank-mounted magneto-inertial sensors: application to elderly, hemiparetic, parkinsonian and choreic gait.

J Neuroeng Rehabil 2014 Nov 11;11:152. Epub 2014 Nov 11.

Information Engineering Unit, Department of Political Sciences, Communication Sciences and Information Engineering (POLCOMING), University of Sassari, V,le Mancini 5, 07100 Sassari, Italy.

Background: The step-by-step determination of the spatio-temporal parameters of gait is clinically relevant since it provides an estimation of the variability of specific gait patterns associated with frequent geriatric syndromes. In recent years, several methods, based on the use of magneto-inertial units (MIMUs), have been developed for the step-by-step estimation of the gait temporal parameters. However, most of them were applied to the gait of healthy subjects and/or of a single pathologic population. Moreover, spatial parameters in pathologic populations have been rarely estimated step-by-step using MIMUs. The validity of clinically suitable MIMU-based methods for the estimation of spatio-temporal parameters is therefore still an open issue. The aim of this study was to propose and validate a method for the determination of both temporal and spatial parameters that could be applied to normal and heavily compromised gait patterns.

Methods: Two MIMUs were attached above each subject's ankles. An instrumented gait mat was used as gold standard. Gait data were acquired from ten hemiparetic subjects, ten choreic subjects, ten subjects with Parkinson's disease and ten healthy older adults walking at two different gait speeds. The method detects gait events (GEs) taking advantage of the cyclic nature of gait and exploiting some lower limb invariant kinematic characteristics. A combination of a MIMU axes realignment along the direction of progression and of an optimally filtered direct and reverse integration is used to determine the stride length.

Results: Over the 4,514 gait cycles analyzed, neither missed nor extra GEs were generated. The errors in identifying both initial and final contact at comfortable speed ranged between 0 and 11 ms for the different groups analyzed. The stride length was estimated for all subjects with less than 3% error.

Conclusions: The proposed method is apparently extremely robust since gait speed did not substantially affect its performance and both missed and extra GEs were avoided. The spatio-temporal parameters estimates showed smaller errors than those reported in previous studies and a similar level of precision and accuracy for both healthy and pathologic gait patterns. The combination of robustness, precision and accuracy suggests that the proposed method is suitable for routine clinical use.
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http://dx.doi.org/10.1186/1743-0003-11-152DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4242591PMC
November 2014

In vivo glenohumeral translation under anterior loading in an open-MRI set-up.

J Biomech 2014 Nov 28;47(15):3771-5. Epub 2014 Sep 28.

Orthopaedic Department, University Hospital Basel, University of Basel, Basel, Switzerland.

The evaluation of the glenohumeral joint laxity requires the estimate of displacements of the humeral head centre (HHC) with respect to the glenoid. To the authors׳ knowledge, several studies have been conducted to estimate HHC translations in vivo but data under anterior loading conditions has not been collected yet. Aim of this study was to develop a non-invasive experimental methodology based on magnetic resonance (MR) imaging for the in vivo evaluation of the HHC translations due to an anteriorly directed force. Fourteen asymptomatic shoulders were acquired using a horizontal open MR scanner with the subjects in the supine position both at 15° and 90° of arm abduction with and without an anterior force of 20N applied at the HHC level. When no load was applied, from 15° to 90° of arm abduction, the HHC moved, anteriorly (1.5±1.3mm) and superiorly (1.8±1.3mm) while smaller displacements were observed medio-laterally (0.4±0.7mm). Under the application of the anterior force the 3D displacement of the HHC with respect to the glenoid was 1.6±1.2mm and 1.3 ±0.7mm, respectively at 15° and 90° of arm abduction. The level of precision associated to the GHJ translation was less than 0.33mm along all directions i.e. one order of magnitude smaller than the relevant translations. In conclusion, the MRI-based methodology allowed for the analysis of HHC displacements under conditions of anterior loads within an acceptable level of reliability.
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http://dx.doi.org/10.1016/j.jbiomech.2014.09.021DOI Listing
November 2014

The effect of supraspinatus tears on glenohumeral translations in passive pitching motion.

Am J Sports Med 2014 Oct 8;42(10):2455-62. Epub 2014 Sep 8.

Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.

Background: Supraspinatus tears are common in pitchers. However, the effect of these tears on glenohumeral (GH) mechanics is incompletely understood.

Purpose/hypothesis: To describe the effect of supraspinatus tears and repairs on GH kinematics during an abbreviated throwing motion using the intact shoulder girdle. The hypothesis was that supraspinatus tears would lead to an increase of GH translation in the coronal plane and supraspinatus repairs would restore GH kinematics.

Study Design: Controlled laboratory study.

Methods: Six shoulders from 3 fresh-frozen cadavers were tested in a novel 7 degrees of freedom robotic testing system. Torsos were mounted and the wrist was pinned to an actuator mounted on an upper frame. After the deltoid was removed, the shoulders were studied during an abbreviated throwing motion (ATM) from maximum external rotation to the midcoronal plane to establish a baseline. The ATM was repeated after creation of a 1-cm supraspinatus tear, after creation of a 3-cm supraspinatus tear, and after repair with a transosseous equivalent (TOE) technique. Retroreflective bone markers and high-speed infrared cameras were used to measure GH kinematics and calculate the center of rotation of the GH joint (CORGH) instantaneously.

Results: The 1- and 3-cm supraspinatus tears did not significantly alter GH translation. The TOE repair shifted the CORGH posteriorly, as evidenced by a significant decrease in the overall GH translation in all 3 planes (P = .003, .019, and .026, for x-y, y-z, and x-z planes, respectively).

Conclusion: In contrast to a TOE repair of the supraspinatus tendon, isolated supraspinatus tears did not perturb GH kinematics in this cadaveric model of the throwing shoulder.

Clinical Relevance: In throwing athletes, treatment of rotator cuff tears should be addressed with caution to avoid an unintended alteration in GH kinematics due to overtightening of the tendon.
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http://dx.doi.org/10.1177/0363546514547348DOI Listing
October 2014
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