Jeroen H. M. Bergmann

A portable system for collecting anatomical joint angles during stair ascent: a comparison with an optical tracking device

BackgroundAssessments of stair climbing in real-life situations using an optical tracking system are lacking, as it is difficult to adapt the system for use in and around full flights of stairs. Alternatively, a portable system that consists of inertial measurement units (IMUs) can be used to collect anatomical joint angles during stair ascent. The purpose of this study was to compare the anatomical joint angles obtained by IMUs to those calculated from position data of an optical tracking device.MethodsAnatomical joint angles of the thigh, knee and ankle, obtained using IMUs and an optical tracking device, were compared for fourteen healthy subjects. Joint kinematics obtained with the two measurement devices were evaluated by calculating the root mean square error (RMSE) and by calculating a two-tailed Pearson product-moment correlation coefficient (r) between the two signals.ResultsStrong mean correlations (range 0.93 to 0.99) were found for the angles between the two measurement devices, as well as an average root mean square error (RMSE) of 4 degrees over all the joint angles, showing that the IMUs are a satisfactory system for measuring anatomical joint angles.ConclusionThese highly portable body-worn inertial sensors can be used by clinicians and researchers alike, to accurately collect data during stair climbing in complex real-life situations.

Contribution of the Reverse Endoprosthesis to Glenohumeral Kinematics

AbstractAfter placement of a reverse shoulder endoprosthesis, range of motion is usually still compromised. To what extent this occurs from limitation in motion of the reverse endoprosthesis is, however, unclear. We measured the motion pattern of 16 patients (18 shoulders) during three active and passive range of motion tasks using a six degree-of-freedom electromagnetic tracking device. Despite rotator cuff deficiencies, glenohumeral elevation contributed roughly two-thirds of the total thoracohumeral elevation, which is comparable to healthy subjects. However, patients could not actively use the full range of motion provided by the prosthesis. Although we found considerable interindividual differences in shoulder kinematics, the limitation in glenohumeral range of motion appears related to a lack of generated muscle force and not the design of the prosthesis. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Kinematic and clinical evaluation of shoulder function after primary and revision reverse shoulder prostheses.

HYPOTHESIS Results of the reverse shoulder prosthesis on pain are generally satisfying; however, active range of motion (ROM) is often not optimal, especially after revision. A kinematic and clinical analysis of the reverse prosthesis was performed to provide more precise information on its glenohumeral motion pattern. We hypothesized that the difference in the primary and revision cases is due to differences in the motion in the glenohumeral joint. MATERIALS AND METHODS The motion pattern of 31 patients with a reverse prosthesis (35 shoulders, 19 primary and 16 revisions) was measured during 3 active ROM tasks-forward flexion, abduction, and axial rotation. Average age was 71 ± 8 years (range, 58-85 years). Average follow-up was 23 ± 14 months (range, 4-63 months). Kinematic measurements were performed with a 3-dimensional electromagnetic tracking device. Clinical evaluation was performed by obtaining Constant score, Disabilities of Arm, Shoulder and Hand (DASH) score, and the Simple Shoulder Test (SST). Acromial-prosthetic distance was measured on anteroposterior radiographs. RESULTS Primary placed prostheses showed significantly better active glenohumeral motion than revisions for forward flexion (71° ± 18° vs 53° ± 26°, P < .05), abduction (64° ± 15° vs 46° ± 24°, P < .05), and active external rotation (31° ± 25° vs 13° ± 16°, P < .05). Constant score improved for the whole group from 24 (range, 5-47) to 50 (range, 8-87; P < .001), for the primary group from 28 (range, 13-47) to 60 (range, 8-87; P < .001) and for revisions from 20 (range, 5-47) to 38 (range, 11-73; P < .001). Acromial-prosthetic distance showed no significant correlation for active glenohumeral motion. Five shoulders with a deficient teres minor muscle showed no significant decrease of external rotation. CONCLUSION Active ROM is better in primary placed prosthesis, and this difference takes place mainly in the glenohumeral joint. In all our patients, Constant scores improved significantly postoperatively. However, we could not find any clinical correlating parameters to explain this difference.

Procedural differences directly affect timed up and go times.

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Postural prioritization is differentially altered in healthy older compared to younger adults during visual and auditory coded spatial multitasking

Many daily activities require appropriate allocation of attention between postural and cognitive tasks (i.e. dual-tasking) to be carried out effectively. Processing multiple streams of spatial information is important for everyday tasks such as road crossing. Fifteen community-dwelling healthy older (mean age=78.3, male=1) and twenty younger adults (mean age=25.3, male=6) completed a novel bimodal spatial multi-task test providing contextually similar spatial information via separate sensory modalities to investigate effects on postural prioritization. Two tasks, a temporally random visually coded spatial step navigation task (VS) and a regular auditory-coded spatial congruency task (AS) were performed independently (single task) and in combination (multi-task). Response time, accuracy and dual-task costs (% change in multi-task condition) were determined. Results showed a significant 3-way interaction between task type (VS vs. AS), complexity (single vs. multi) and age group for both response time (p ≤ 0.01) and response accuracy (p ≤ 0.05) with older adults performing significantly worse than younger adults. Dual-task costs were significantly greater for older compared to younger adults in the VS step task for both response time (p ≤ 0.01) and accuracy (p ≤ 0.05) indicating prioritization of the AS over the VS stepping task in older adults. Younger adults display greater AS task response time dual task costs compared to older adults (p ≤ 0.05) indicating VS task prioritization in agreement with the posture first strategy. Findings suggest that novel dual modality spatial testing may lead to adoption of postural strategies that deviate from posture first, particularly in older people. Adoption of previously unreported postural prioritization strategies may influence balance control in older people.

A novel method for determining ground-referenced contacts during stair ascent: Comparing relative hip position to quiet standing hip height

Stair climbing can be measured using body-fixed sensors, whereby the origin and axes of the coordinate system are fixed with respect to the geometry of a body segment. These sensors can be part of a portable system, which provides the possibility to collect data in complex real-life environments. However due to the fact that the sensors are body-fixed, difficulties in determining the ground-based parameters of stair ascent can occur. The purpose of this study is to present a new approach for determining initial contacts based on a multi-chain biomechanical model combined with a new analysis method, in which relative hip height is compared to hip height during normal standing. Initial contacts obtained from the proposed method were compared to those obtained using an optical tracking device. An average absolute timing difference ranging from 0.04 (SD + or - 0.03) to 0.06 (+ or - 0.03) s and a root mean square error ranging from 0.05 to 0.07 s were found between the two techniques. This shows that the new approach presented in this study can be used to accurately determine initial contacts during stair ascent using portable equipment.

Examining Everyday Speech and Motor Symptoms of Parkinson's Disease for Diagnosis and Progression Tracking

Statistical methods to correlate multiple variables has long been applied in many fields of research. This paper applies such techniques to Unified Parkinsons Disease Rating Scale (UPDRS) data to examine relationships between speech and movement variables. This data analysis uses select speech and motor variables to explore Parkinsons Disease (PD) symptom correlations. The analysis is a prerequisite study of speech and movement symptoms prior to collecting data from everyday living in PD patients using HCI systems for movement and AI methods for analyzing speech and language. This data analysis is a first level examination of the current gold standards for measuring speech and movement in PD patients.