Using merged kinematic and anatomical data to evaluate humeral motion estimation: a pilot study

in Computer Methods in Biomechanics and Biomedical Engineering. Imaging & Visualization (2013)

Optoelectronic systems are widely used in 3D motion capture. However, the reliability of the motion estimation depends on soft tissue artifacts and should therefore be validated. Two different sets of ... [more ▼]

Optoelectronic systems are widely used in 3D motion capture. However, the reliability of the motion estimation depends on soft tissue artifacts and should therefore be validated. Two different sets of humeral markers were studied on four subjects. Anatomical and kinematic measurements were combined and the plausibility of the relative position of the bones in the glenohumeral joint during motion was evaluated using a new coherence index. Our findings show that an identical protocol leads to a large variability of the articular coherence for the subjects. However the use of an extra marker on the distal part of the humerus improves the humeral kinematics for three of the four subjects. Scientists and clinicians using 3D systems should remain aware of the influence of subject-specific morphology on the accuracy of the measure. Differences with a reference group may come from clinical reasons but also from measurement errors due to the inter-individual morphological differences. [less ▲]

Validated Extraction of Gait Events from 3D Accelerometer Recordings

in IEEE International Conference on 3D Imaging (IC3D) (2012, December)

This work is part of a project that deals with the three-dimensional (3D) analysis of normal and pathological gaits based on a newly developed system for clinical applications, using low-cost wireless ... [more ▼]

This work is part of a project that deals with the three-dimensional (3D) analysis of normal and pathological gaits based on a newly developed system for clinical applications, using low-cost wireless accelerometers and a signal processing algorithm. This system automatically extracts relevant gait events such as the heel strikes (HS) and the toe-offs (TO), which characterize the stance and the swing phases of walking. The performances of the low-cost accelerometer hardware and related algorithm have been compared to those obtained by a kinematic 3D analysis system and a force plate, used as gold standard methods. The HS and TO times obtained from the gait data of 7 healthy volunteers (147 trials) have been found to be (mean ± standard deviation) 0.42±7.92 ms and 3.11±10.08 ms later than those determined by the force plate, respectively. The experimental results demonstrate that the new hardware and associated algorithm constitute an effective low-cost gait analysis system, which could thus be used for the assessment of mobility in routine clinical practice. [less ▲]

3D Analysis of Normal and Pathological Gait Based on Low-Cost Wireless Accelerometers

in URSI Benelux Forum 2012 “Antennas: multiple designs, multiple applications” (2012)

We describe the principle and use of a new low-cost, wireless, 3-axis accelerometer-based device that records acceleration signals and automatically analyses them to characterize normal and pathological ... [more ▼]

We describe the principle and use of a new low-cost, wireless, 3-axis accelerometer-based device that records acceleration signals and automatically analyses them to characterize normal and pathological gait. [less ▲]

Reproducibility and repeatability of upper limb landmarks palpation for junior operators

Poster (2011, July)

In human motion analysis, bone motions are usually expressed relatively to anatomical reference frames. The anatomical reference frames are constructed thanks to the localization of bony landmarks during ... [more ▼]

In human motion analysis, bone motions are usually expressed relatively to anatomical reference frames. The anatomical reference frames are constructed thanks to the localization of bony landmarks during a static phase prior to the acquisitions. These landmarks are identified by means of palpation. Accurate comparison between subjects and studies implies good reproducibility and repeatability of the palpation process. However, all investigators don’t have a long experience in palpation. In this paper, the reproducibility and repeatability of palpation for junior investigators were measured. Results show worse reproducibility and repeatability than what is usually expected. These errors have particularly an influence on the definition of the reference frames of the arm. This study therefore emphasizes on the need of a specific training of operators working in a motion lab. [less ▲]

Location of the best confident scapula cluster during a forward humeral elevation

Poster (2011, July)

Eleven subjects were equipped with a cluster of 120 markers on the scapula. Forward humeral elevation was then performed. Robust estimators are used in order to eliminate high deformation. Results ... [more ▼]

Eleven subjects were equipped with a cluster of 120 markers on the scapula. Forward humeral elevation was then performed. Robust estimators are used in order to eliminate high deformation. Results underline the modification of the best cluster during elevation. Markers located on the lateral posterior part of the acromion were identified. They could be the best ones to measure dynamic scapula rotation during entire elevation. [less ▲]

Evaluation of a geometry-based knee joint compared to a planar knee joint

in Visual Computer (2011)

Today neuromuscular simulations are used in sev- eral fields, such as diagnostics and planing of surgery, to get a deeper understanding of the musculoskeletal system. Dur- ing the last year, new models ... [more ▼]

Today neuromuscular simulations are used in sev- eral fields, such as diagnostics and planing of surgery, to get a deeper understanding of the musculoskeletal system. Dur- ing the last year, new models and datasets have been pre- sented which can provide us with more in-depth simulations and results. The same kind of development has occurred in the field of studying the human knee joint using complex three dimensional finite element models and simulations. In the field ofmusculoskeletal simulations, no such knee joints can be used. Instead themost common knee joint description is an idealized knee joint with limited accuracy or a planar knee joint which only describes the knee motion in a plane. In this paper, a new knee joint based on both equations and geometry is introduced and compared to a common clinical planar knee joint. The two kinematical models are analyzed using a gait motion, and are evaluated using the muscle ac- tivation and joint reaction forces which are compared to in- vivo measured forces. We show that we are able to predict the lateral, anterior and longitudinal moments, and that we are able to predict better knee and hip joint reaction forces. [less ▲]

Validation of musculoskeletal models: the importance of trend validations

Conference (2010, September)

Prediction of knee loads using a lower extremity model based on the Klein Horsman data set

Conference (2010, June)

In this paper, the in-vivo loads of the knee joint provided by an instrumented prosthesis (Fregly et al., 2010, Lin et al., 2010, Kim et al., 2009) are compared to the results obtained from an ... [more ▼]

In this paper, the in-vivo loads of the knee joint provided by an instrumented prosthesis (Fregly et al., 2010, Lin et al., 2010, Kim et al., 2009) are compared to the results obtained from an implementation of the Klein Horsman data set (2007) in the AnyBody Modeling System. The lateral and medial knee contact forces are estimated directly from the knee modeled as a modified revolute joint. As such, this study presents what can be achieved by estimating the knee contact forces from a simplified knee model. [less ▲]

Contribution à l’élaboration d’un espace commun de représentation pour l’analyse morpho-fonctionnelle du membre supérieur : application à l’articulation glénohumérale

Doctoral thesis (2009)

Locomotor disorders comprehension is limited by the absence of dynamic 3D imaging technology. 3D imagers give access to accurate but static information about bones morphology. On the other hand, motion ... [more ▼]

Locomotor disorders comprehension is limited by the absence of dynamic 3D imaging technology. 3D imagers give access to accurate but static information about bones morphology. On the other hand, motion analysis systems provide dynamic measures. However, these measures may be distorted by the presence of soft tissues between the bones and the skin surface. First, we study a new method for correcting soft tissues artifacts when using external markers for motion estimation. This method is based on a surfacic approach and aims to follow the deformation created by the scapula on the skin surface. A robust registration algorithm, called IMCP, is used. This algorithm, developed in previous works, has been modified and adapted to be more specific to the study context: motion analysis using external markers. The improvements concern post-processing so as to make the most of the information mutualization properties of the IMCP, a way to take into account the influence of the edges of the markers clusters, and finally the optimization of the processing time thanks to multi-threading developments. In a second time, a specific MRI protocol is developed in order to allow morpho-functional analysis. Moreover, articular coherence indicators are proposed for the glenohumeral joint. These indicators are adapted to the case of errors in motion estimation. The results show that the use of a markers cluster covering all the scapula do not allow to follow the scapula print at skin surface. Thanks to simulation studies, two hypotheses are proposed to explain these results: the noise created by the soft tissues is too significant, and / or the available skin resolution is not sufficient. The relevance of proposing markerless analysis is so emphasized. Our morpho-functional study on the glenohumeral joint shows the significant influence of the motion analysis protocol on joint coherence during bones animation. The placement of the markers on the scapula and on the humerus as well as the choice of the motion estimation algorithm have a large influence on the bony structures motion estimation. [less ▲]

Shoulder motion analysis using simultaneous skin shape registration.

in Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society (2007, August)

A new non-invasive approach is proposed to study joint motions. It is based on dynamic tracking of the skin shape. A robust simultaneous registration algorithm (Iterative Median Closest Point) is used to ... [more ▼]

A new non-invasive approach is proposed to study joint motions. It is based on dynamic tracking of the skin shape. A robust simultaneous registration algorithm (Iterative Median Closest Point) is used to follow the evolving shape and compute the rigid motion of the underlying bone structures. This new method relies on the differentiation of the rigid and elastic parts of the shape motion. A skin marker network is tracked by a set of infrared cameras. Unlike usual techniques, the algorithm tracks the instantaneous polyhedral shape embedding this network. This innovating approach is expected to minimize bias effect of skin sweeps and give some new information about the underlying soft tissue activities. Current application addresses the motion of the shoulder complex (humerus, clavicle and scapula). It is compared with two marker-based methods published in the literature. Preliminary results show significant differences between these three approaches. The new approach measurements give rise to greater rotations. [less ▲]