The biomechanical role of the lacertus fibrosus of the biceps brachii Muscle

PURPOSE

The lacertus fibrosus (LF) is involved in various surgeries. However, the biomechanical contribution of the LF remains unclear. The aim of this study was to determine the role of the lacertus fibrosus on the elbow and forearm kinematics and on the biceps brachii muscle lever arms.

METHODS

This biomechanical study was performed on seven fresh-frozen upper limbs of cadavers. Elbow flexion, forearm supination, and biceps brachii muscle lever arms were analyzed in the intact conditions (I) and after superficial (R) and deep part (R2) of the lacertus fibrosus release, respectively.

RESULTS

Elbow flexion shows a significant difference (p < 0.0001) between I, R, R2. Abduction/adduction shows a significant difference between I-R (p < 0.0001) and I-R2 (p < 0.0001). Supination does not show a significant difference in mean maximum amplitude, but between 40 and 70%, there are significant differences. There is a significant mean decrease of lever arm in flexion (28%) and supination (50%) after superficial and deep part of the lacertus fibrosus release.

CONCLUSION

The results of this study show that the lacertus fibrosus increases the lever arm during flexion and supination. It limits the flexion and abduction of the elbow and supination of the forearm. Lacertus fibrosus maintains the rhythmicity between the elbow flexion and supination of the forearm.

LEVEL OF EVIDENCE

Basic science study, biomechanics.

Metatarsal arch deformation and forefoot kinematics during gait in asymptomatic subjects

This study aimed to investigate both foot arch-shaped architecture and forefoot kinematics during gait. Using a dedicated three-compartment forefoot subdivision, we studied asymptomatic subjects and quantified disorders related to the metatarsal arch. Foot motion and arch shape were measured in 30 healthy subjects with a motion-capture system and force plates. Kinematic results were expressed using a novel model, which anatomically divides the forefoot into three parts. This model integrated the medial longitudinal arch angle and the metatarsal arch height and width. During the first part of stance phase, the medial longitudinal arch flattens and all foot segments move toward dorsiflexion. During terminal stance and preswing phase, medial longitudinal and metatarsal arch restoration was noted with plantarflexion of all segments, an eversion and abduction of the medial forefoot, and an inversion and adduction of the lateral forefoot. Kinematics obtained with the proposed forefoot model corroborates metatarsal arch restoration in late stance. This observation supports the fact that foot architecture is supple until midstance and subsequently creates a rigid lever arm with restored arches to support propulsion. This study’s results and methods highlight the potential of the three-compartment model for use in clinical decision-making.

Pelvis and femur shape prediction using principal component analysis for body model on seat comfort assessment. Impact on the prediction of the used palpable anatomical landmarks as predictors

A personalized pelvis and femur shape is required to build a finite element buttock thigh model when experimentally investigating seating discomfort. The present study estimates the shape of pelvis and femur using a principal component analysis (PCA) based method with a limited number of palpable anatomical landmarks (ALs) as predictors. A leave-one-out experiment was designed using 38 pelvises and femurs from a same sample of adult specimens. As expected, prediction errors decrease with the number of ALs. Using the maximum number of easily palpable ALs (13 for pelvis and 4 for femur), average errors were 5.4 and 4.8 mm respectively for pelvis and femur. Better prediction was obtained when the shapes of pelvis and femur were predicted separately without merging the data of both bones. Results also show that the PCA based method is a good alternative to predict hip and lumbosacral joint centers with an average error of 5.0 and 9.2 mm respectively.

The Use of Mobile Games to Assess Cognitive Function of Elderly with and without Cognitive Impairment

BACKGROUND

In the past few years numerous mobile games have been developed to train the brain. There is a lack of information about the relation between the scores obtained in these games and the cognitive abilities of the patients.

OBJECTIVE

The aim of this study was to determine whether or not mobile games can be used to assess cognitive abilities of elderly.

METHODS

Twenty healthy young adults, 29 old patients with cognitive impairments (Mini-Mental State Exam (MMSE) [20- 24]) and 27-aged controls participated in this study. Scores obtained in 7 mobile games were correlated with MMSE and the Addenbrooke's Cognitive Evaluation revised (ACE-R).

RESULTS

Statistically significant differences were found for all games between patients with cognitive impairments and the aged controls. Correlations between the average scores of the games and the MMSE and ACE-R are significant (R = 0.72 [p < 0.001] and R = 0.81 [p < 0.001], respectively).

CONCLUSION

Scores of cognitive mobile games could be used as an alternative to MMSE and ACE-R to evaluate cognitive function of aged people with and without cognitive impairment at least when MMSE is higher than 20/30.

Automated functional upper limb evaluation of patients with Friedreich ataxia using serious games rehabilitation exercises

Background

Friedreich ataxia (FRDA) is a disease with neurological and systemic involvement. Clinical assessment tools commonly used for FRDA become less effective in evaluating decay in patients with advanced FRDA, particularly when they are in a wheelchair. Further motor worsening mainly impairs upper limb function. In this study, we tested if serious games (SG) developed for rehabilitation can be used as an assessment tool for upper limb function even in patients with advanced FRDA.

Methods

A specific SG has been developed for physical rehabilitation of patients suffering from neurologic diseases. The use of this SG, coupled with Kinect sensor, has been validated to perform functional evaluation of the upper limbs with healthy subjects across lifespan. Twenty-seven FRDA patients were included in the study. Patients were invited to perform upper limb rehabilitation exercises embedded in SG. Motions were recorded by the Kinect and clinically relevant parameters were extracted from the collected motions. We tested if the existence of correlations between the scores from the serious games and the severity of the disease using clinical assessment tools commonly used for FRDA. Results of patients were compared with a group a healthy subjects of similar age.

Results

Very highly significant differences were found for time required to perform the exercise (increase of 76%, t(68) = 7.22, P < 0.001) and for accuracy (decrease of 6%, t(68) = − 3.69, P < 0.001) between patients and healthy subjects. Concerning the patients significant correlations were found between age and time (R = 0.65, p = 0.015), accuracy (R = − 0.75, p = 0.004) and the total displacement of upper limbs. (R = 0.55, p = 0.031). Statistically significant correlations were found between the age of diagnosis and speed related parameters.

Conclusions

The results of this study indicate that SG reliably captures motor impairment of FRDA patients due to cerebellar and pyramidal involvement. Results also show that functional evaluation of FRDA patients can be performed during rehabilitation therapy embedded in games with the patient seated in a wheelchair.

Trial registration

The study was approved as a component of the EFACTS study (Clinicaltrials.gov identifier NCT02069509, registered May 2010) by the local institutional Ethics Committee (ref. P2010/132).

3D Analysis of Upper Limbs Motion during Rehabilitation Exercises Using the KinectTM Sensor: Development, Laboratory Validation and Clinical Application

Optoelectronic devices are the gold standard for 3D evaluation in clinics, but due to the complexity of this kind of hardware and the lack of access for patients, affordable, transportable, and easy-to-use systems must be developed to be largely used in daily clinics. The Kinect^TM sensor has various advantages compared to optoelectronic devices, such as its price and transportability. However, it also has some limitations: (in)accuracy of the skeleton detection and tracking as well as the limited amount of available points, which makes 3D evaluation impossible. To overcome these limitations, a novel method has been developed to perform 3D evaluation of the upper limbs. This system is coupled to rehabilitation exercises, allowing functional evaluation while performing physical rehabilitation. To validate this new approach, a two-step method was used. The first step was a laboratory validation where the results obtained with the Kinect^TM were compared with the results obtained with an optoelectronic device; 40 healthy young adults participated in this first part. The second step was to determine the clinical relevance of this kind of measurement. Results of the healthy subjects were compared with a group of 22 elderly adults and a group of 10 chronic stroke patients to determine if different patterns could be observed. The new methodology and the different steps of the validations are presented in this paper.

Further consideration of the curvature of the Neandertal Femur

OBJECTIVES

Neandertal femora are particularly known for having a marked sagittal femoral curvature. This study examined femoral curvature in Neandertals in comparison to a modern human population from Belgium by the use of three-dimensional (3D) quadric surfaces modeled from the bone surface. 3D models provide detailed information and enabled femoral curvature to be analyzed in conjunction with other morphological parameters.

MATERIALS AND METHODS

3D models were created from CT scans of 75 modern human femora and 7 Neandertal femora. Quadric surfaces (QS) were created from the triangulated surface vertices in all areas of interest (neck, head, diaphyseal shaft, condyles) extracted from previously placed anatomical landmarks. The diaphyseal shaft was divided into five QS shapes and curvature was measured by degrees of difference between QS shapes. Each bone was placed in a local coordinate system enabling each bone to be analyzed in the same way.

RESULTS

The use of 3D quadric surface fitting allowed the distribution of curvature with similarly curved femora to be analyzed and the different patterns of curvature between the two groups to be determined. The Neandertals were shown to have a higher degree of femoral curvature and a more distal point of femoral curvature than the modern human population from Belgium.

CONCLUSIONS

Morphological aspects of the Neandertal femur are different from this modern human population although mainly seem unrelated to femoral curvature. The relative lack of correlations with other femoral bony morphological factors suggests femoral curvature variations may be related to other aspects.

How different are the Kebara 2 ribs to modern humans?

This study analyses rib geometric parameters of individual ribs of 14 modern human subjects (7 males and 7 females) in comparison to the reconstructed ribs of the Kebara 2 skeleton which was taken from the reconstruction of a Neandertal thorax by Sawyer & Maley (2005). Three-dimensional (3D) models were segmented from CT scans and each rib vertex cloud was placed into a local coordinate system defined from the rib principal axes. Rib clouds were then analysed using best fitting ellipses of the external contours of the cross-section areas. The centroid of each ellipse was then used to measure the centroidal pathway between each slice (rib midline). Curvature of the ribs was measured from the mid-line of the ribs as the sum of angles between successive centroids in adjacent cross sections. Distinct common patterns were noted in all rib geometric parameters for modern humans. The Kebara 2 reconstructed ribs also followed the same patterns. This study demonstrated that there are differences between the sexes in rib geometrical parameters, with females showing smaller rib width, chord length and arc length, but greater curvature (rib torsion, rib axial curvature, rib anterior-posterior bending) than males. The Kebara 2 reconstructed ribs were within the modern human range for the majority of geometrical parameters.

Relationship between costovertebral joint kinematics and lung volume in supine humans

This study investigates the relationship between the motion of the first ten costovertebral joints (CVJ) and lung volume over the inspiratory capacity (IC) using detailed kinematic analysis in a sample of 12 asymptomatic subjects. Retrospective codified spiral-CT data obtained at total lung capacity (TLC), middle of inspiratory capacity (MIC) and at functional residual capacity (FRC) were analysed. CVJ 3D kinematics were processed using previously-published methods. We tested the influence of the side, CVJ level and lung volume on CVJ kinematics. In addition, the correlations between anthropologic/pulmonary variables and CVJ kinematics were analysed. No linear correlation was found between lung volumes and CVJ kinematics. Major findings concerning 3D kinematics can be summarized as follows: 1) Ranges-of-motion decrease gradually with increasing CVJ level; 2) rib displacements are significantly reduced at lung volumes above the MIC and do not differ between CVJ levels; 3) the axes of rotation of the ribs are similarly oriented for all CVJ levels.

A novel method for in-vivo evaluation of finger kinematics including definition of healthy motion patterns

BACKGROUND

Despite recent progress in motion capture technology, such as stereophotogrammetry based on the tracking of markers set on the subject, it remains challenging to develop a complete protocol for in-vivo functional evaluation of the hand. The current practical problems regarding small anatomical segments, such as the fingers, are mainly due to the high concentration of markers in a relatively reduced volume.

METHODS

This paper proposes a novel procedure for hand functional analysis by analysing finger behaviour along the main displacement plane simultaneously with combined motions. The objective was two-fold. For one thing, a novel data collection protocol was implemented, which includes specific setting of the motion capture system and the development of finger marker clusters. The second purpose of this study was to create a reference database of a healthy sample for further clinical investigation. Twenty healthy volunteers took part in the study. Analytical motions (flexion/extension and abduction/adduction) of all five fingers were recorded.

FINDINGS

Results showed good correspondence with the literature. Specific kinematic behaviour of each analysed joint is reported. Statistically significant differences were found between the right and left sides of the subjects for the flexion/extension movement only, between the finger joints and between the fingers for all movements. No significant difference was found between genders. A validation protocol was performed, which proved the validity of the presented methodology.

INTERPRETATION

The protocol appears suitable for further use in motion analysis and for musculoskeletal modelling of the hand. It will also be considered for clinical application.

Interchangeability of the Wii Balance Board for Bipedal Balance Assessment

Background

Since 2010, an increasing interest in more portable and flexible hardware for balance and posture assessment led to previously published studies determining whether or not the Wii Balance Board could be used to assess balance and posture, both scientifically and clinically. However, no previous studies aimed at comparing results from different Wii Balance Boards for clinical balance evaluation exist.

Objective

The objective of this crossover study is to assess the interchangeability of the Wii Balance Board.

Methods

A total of 6 subjects participated in the study and their balance was assessed using 4 different Wii Balance Boards. Trials were recorded simultaneously with Wii Balance Boards and with a laboratory force plate. Nine relevant clinical parameters were derived from center of pressure displacement data obtained from Wii Balance Board and force plate systems. Intraclass correlation coefficients (ICC), F tests, and Friedman tests were computed to assess the agreement between trials and to compare the Wii Balance Board and force plate results.

Results

Excellent correlations were found between the Wii Balance Board and force plate (mean ρ =.83). With the exception of 2 parameters, strong to excellent agreements were found for the 7 remaining parameters (ICC=.96). No significant differences were found between trials recorded with different Wii Balance Boards.

Conclusions

Our results indicate that for most of the parameters analyzed, balance and posture assessed with one Wii Balance Board were statistically similar to results obtained from another. Furthermore, the good correlation between the Wii Balance Board and force plate results shows that Wii Balance Boards can be reliably used for scientific assessment using most of the parameters analyzed in this study. These results also suggest that the Wii Balance Board could be used in multicenter studies and therefore, would allow for the creation of larger populations for clinical studies.

Trial Registration

Ethical Committee of the Erasme Hospital (CCB B406201215142).

Balance improvement after physical therapy training using specially developed serious games for cerebral palsy children: preliminary results

PURPOSE

Cerebral palsy (CP) leads to various clinical signs mainly induced by muscle spasticity and muscle weakness. Among these ones impaired balance and posture are very common. Traditional physical therapy exercise programs are focusing on this aspect, but it is difficult to motivate patients to regularly perform these exercises, especially at home without therapist supervision. Specially developed serious games (SG) could therefore be an interesting option to motivate children to perform specific exercise for balance improvement.

METHOD

Ten CP children participated in this study. Patients received four sessions of SG included into conventional therapy (1 session of 30 min a week during 4 weeks). Trunk control and balance were assessed using Trunk Control Motor Scale (TCMS) before and after interventions.

RESULTS

Children presented a significant improvement in TCMS global score after interventions [37.6 (8.7) and 39.6 (9.5) before and after interventions, respectively, p = 0.04].

CONCLUSION

SG could therefore be an interesting option to integrate in the conventional treatment of CP children. Implication for Rehabilitation Cerebral palsy (CP) leads to balance issues. Rehabilitation exercises are not performed (enough) at home. Serious games (SG) could increase patients' motivation. SG increase balance control of CP children.

Physiologically corrected coupled motion during gait analysis using a model-based approach

Gait analysis is used in daily clinics for patients' evaluation and follow-up. Stereophotogrammetric devices are the most used tool to perform these analyses. Although these devices are accurate results must be analyzed carefully due to relatively poor reproducibility. One of the major issues is related to skin displacement artifacts. Motion representation is recognized reliable for the main plane of motion displacement, but secondary motions, or combined, are less reliable because of the above artifacts. Model-based approach (MBA) combining accurate joint kinematics and motion data was previously developed based on a double-step registration method. This study presents an extensive validation of this MBA method by comparing results with a conventional motion representation model. Thirty five healthy subjects participated to this study. Gait motion data were obtained from a stereophotogrammetric system. Plug-in Gait model (PiG) and MBA were applied to raw data, results were then compared. Range-of-motion, were computed for pelvis, hip, knee and ankle joints. Differences between PiG and MBA were then computed. Paired-sample t-tests were used to compare both methods. Normalized root-mean square errors were also computed. Shapes of the curves were compared using coefficient of multiple correlations. The MBA and PiG approaches shows similar results for the main plane of motion displacement but statistically significative discrepancies appear for the combined motions. MBA appear to be usable in applications (such as musculoskeletal modeling) requesting better approximations of the joints-of-interest thanks to the integration of validated joint mechanisms.

Effect of anatomical landmark perturbation on mean helical axis parameters of in vivo upper costovertebral joints

The literature concerning quantification of costovertebral joint (CVJ) motion under in vivo conditions is scarce. Most papers concerning this topic are related to ex vivo loading conditions. In vivo protocols are available from the literature to determine rib and vertebra kinematics but new developments are needed to improve data processing concerning CVJ behaviour obtained from discrete breathing positions showing limiting ranges-of-motion and sensitive to noise. Data from previous work were used to implement a method analyzing mean helical axis (MHA) and pivot point parameters of the CVJ complexes. Several levels of noises were estimated within Monte-Carlo simulations to optimize MHA results. MHA parameters were then used to transform and define a CVJ-specific local coordinate system. This study proposes an improvement for CVJ kinematics processing and description from in vivo data obtained from computed tomography. This methodology emphasizes the possibility to work with variability of MHA parameters using Monte-Carlo procedures on anatomical landmark coordinates and to define a local coordinate system from this particular joint behaviour. Results from the CVJ joint model are closer to a hinge joint (secondary motions inferior to 3°) when anatomical frames are expressed from MHA orientation. MHA orientation and position data obtained from the proposed method are relevant according to angular dispersion obtained (from 7.5° to 13.9°) and therefore relevant to define behaviour of CVJ.

A portable system for foot biomechanical analysis during gait

Modeling the foot is challenging due to its complex structure compared to most other body segments. To analyze the biomechanics of the foot, portable devices have been designed to allow measurement of temporal, spatial, and pedobarographic parameters. The goal of this study was to design and evaluate a portable system for kinematic and dynamic analysis of the foot during gait. This device consisted of a force plate synchronized with four cameras and integrated into a walkway. The complete system can be packaged for transportation. First, the measurement system was assessed using reference objects to evaluate accuracy and precision. Second, nine healthy participants were assessed during gait trials using both the portable and Vicon systems (coupled with a force plate). The ankle and metatarsophalangeal (MP) joint angles and moments were computed, as well as the ground reaction force (GRF). The intra- and inter-subject variability was analyzed for both systems, as well as the inter-system variation. The accuracy and precision were, respectively 0.4 mm and 0.4 mm for linear values and 0.5° and 0.6° for angular values. The variability of the portable and Vicon systems were similar (i.e., the inter-system variability never exceeded 2.1°, 0.081 Nmkg(-1) and 0.267 Nkg(-1) for the angles, moments and GRF, respectively). The inter-system differences were less than the inter-subject variability and similar to the intra-subject variability. Consequently, the portable system was considered satisfactory for biomechanical analysis of the foot, outside of a motion analysis laboratory.

In vivo thorax 3D modelling from costovertebral joint complex kinematics

BACKGROUND

The costovertebral joint complex is mechanically involved in both respiratory function and thoracic spine stability. The thorax has been studied for a long time to understand its involvement in the physiological mechanism leading to specific gas exchange. Few studies have focused on costovertebral joint complex kinematics, and most of them focused on experimental in vitro analysis related to loading tests or global thorax and/or lung volume change analysis. There is however a clinical need for new methods allowing to process in vivo clinical data. This paper presents results from in vivo analysis of the costovertebral joint complex kinematics from clinically-available retrospective data.

METHODS

In this study, in vivo spiral computed tomography imaging data were obtained from 8 asymptomatic subjects at three different lung volumes (from total lung capacity to functional residual capacity) calibrated using a classical spirometer. Fusion methods including 3D modelling and kinematic analysis were used to provide 3D costovertebral joint complex visualization for the true ribs (i.e., first seven pairs of ribs).

FINDINGS

The 3D models of the first seven pairs of costovertebral joint complexes were obtained. A continuous kinematics simulation was interpolated from the three discrete computerized tomography positions. Helical axis representation was also achieved.

INTERPRETATION

Preliminary results show that the method leads to meaningful and relevant results for clinical and pedagogical applications. Research in progress compares data from a sample of healthy volunteers with data collected from patients with cystic fibrosis to obtain new insights about the costovertebral joint complex range of motion and helical axis assessment in different pathological conditions.

Determination of repeatability of kinect sensor

BACKGROUND

The Kinect™ (Microsoft™, Redmond, WA) sensor, originally developed for gaming purposes, may have interesting possibilities for other fields such as posture and motion assessment. The ability of the Kinect sensor to perform biomechanical measurements has previously been studied and shows promising results. However, interday repeatability of the device is still not known.

MATERIALS AND METHODS

This study assessed the intra- and interday repeatability of the Kinect sensor compared with a standard stereophotogrammetric device during posture assessment for measuring segment lengths. Forty subjects took part in the study. Five motionless captures were performed in one session to assess posture. Data were simultaneously recorded with both devices.

RESULTS

Similar intraclass correlations coefficient (ICC) values were found for intraday (ICC=0.94 for the Kinect device and 0.98 for the stereophotogrammetric device) and interday (ICC=0.88 and 0.87, respectively) repeatability.

CONCLUSIONS

Results of this study suggest that a cost-effective, easy-to-use, and portable single markerless camera offers the same repeatability during posture assessment as an expensive, time-consuming, and nontransportable marker-based device.

The lacertus fibrosus of the biceps brachii muscle: an anatomical study

PURPOSE

The lacertus fibrosus (LF) is involved in various surgical procedures. However, the anatomy, morphometry, topography and biomechanical involvements of LF are not clear. The purpose of this study was to determine the anatomical and morphometric variations of LF, and to correlate this with anthropometric and morphometric measurements of the upper limb. Furthermore, the presence or absence of a deep layer of LF was verified using forearm cross-sections and dissections.

METHODS

This anatomical study was performed by observation of dissections and transverse sections obtained from 50 cadavers. Morphometric analyses [length and width of LF and biceps tendon, stature, length of upper limb, forearm, bi-epicondylar width, forearm perimeter, biceps brachii muscle perimeter (BBm)] were also performed.

RESULTS

The results demonstrated that there was no significant correlation between LF morphology and morphometric upper limb measurements. The deep layer of LF was observed in all specimens.

CONCLUSION

Results of this paper indicate that the LF presents individual characteristics such as length and width. The deeper layer of LF was observed on all specimens. The possible role of LF in force transmission during flexion, BBm moment arm adjustment and supination reduction is discussed in view of these results.

Sex determination using the Probabilistic Sex Diagnosis (DSP: Diagnose Sexuelle Probabiliste) tool in a virtual environment

The hip bone is one of the most reliable indicators of sex in the human body due to the fact it is the most dimorphic bone. Probabilistic Sex Diagnosis (DSP: Diagnose Sexuelle Probabiliste) developed by Murail et al., in 2005, is a sex determination method based on a worldwide hip bone metrical database. Sex is determined by comparing specific measurements taken from each specimen using sliding callipers and computing the probability of specimens being female or male. In forensic science it is sometimes not possible to sex a body due to corpse decay or injury. Skeletalization and dissection of a body is a laborious process and desecrates the body. There were two aims to this study. The first aim was to examine the accuracy of the DSP method in comparison with a current visual sexing method on sex determination. A further aim was to see if it was possible to virtually utilise the DSP method on both the hip bone and the pelvic girdle in order to utilise this method for forensic sciences. For the first part of the study, forty-nine dry hip bones of unknown sex were obtained from the Body Donation Programme of the Université Libre de Bruxelles (ULB). A comparison was made between DSP analysis and visual sexing on dry bone by two researchers. CT scans of bones were then analysed to obtain three-dimensional (3D) virtual models and the method of DSP was analysed virtually by importing the models into a customised software programme called lhpFusionBox which was developed at ULB. The software enables DSP distances to be measured via virtually-palpated bony landmarks. There was found to be 100% agreement of sex between the manual and virtual DSP method. The second part of the study aimed to further validate the method by analysing thirty-nine supplementary pelvic girdles of known sex blind. There was found to be a 100% accuracy rate further demonstrating that the virtual DSP method is robust. Statistically significant differences were found in the identification of sex between researchers in the visual sexing method although both researchers identified the same sex in all cases in the manual and virtual DSP methods for both the hip bones and pelvic girdles.

Foot roll-over evaluation based on 3D dynamic foot scan

Foot roll-over is commonly analyzed to evaluate gait pathologies. The current study utilized a dynamic foot scanner (DFS) to analyze foot roll-over. The right feet of ten healthy subjects were assessed during gait trials with a DFS system integrated into a walkway. A foot sole picture was computed by vertically projecting points from the 3D foot shape which were lower than a threshold height of 15 mm. A 'height' value of these projected points was determined; corresponding to the initial vertical coordinates prior to projection. Similar to pedobarographic analysis, the foot sole picture was segmented into anatomical regions of interest (ROIs) to process mean height (average of height data by ROI) and projected surface (area of the projected foot sole by ROI). Results showed that these variables evolved differently to plantar pressure data previously reported in the literature, mainly due to the specificity of each physical quantity (millimeters vs Pascals). Compared to plantar pressure data arising from surface contact by the foot, the current method takes into account the whole plantar aspect of the foot, including the parts that do not make contact with the support surface. The current approach using height data could contribute to a better understanding of specific aspects of foot motion during walking, such as plantar arch height and the windlass mechanism. Results of this study show the underlying method is reliable. Further investigation is required to validate the DFS measurements within a clinical context, prior to implementation into clinical practice.

[Application of the musculo-skeletal modelling software lhpFusionBox to a paleoanthropological problem: the Spyrou Neandertal moves!]

LhpFusionBox is a program originally designed for biomechanical and clinical studies relating to the musculoskeletal system of anatomically modern humans (AMH). The program has recently been adapted for paleontological purposes and used to reconstruct and biomechanically analyse a fossil hominid. There is no complete Neandertal skeleton in the fossil record. The aim of the study was to reconstruct a complete three-dimensional (3D) model of a Neandertal using the relatively complete Spy II Neandertal and to conduct biomechanical feasibility studies on the knee and hamstring moment arms of the skeleton. Different Neandertal specimens were scaled to the size of Spy II to replace incomplete or missing bones. Biomechanical feasibility studies performed on the knee seem to show that Neandertal and AMHh gait is similar and Neandertals were shown to have larger moment arms in the hamstring muscles, which would have given them a mechanical advantage. The complete Neandertal was printed in 3D and used as the base to create the artistic model of "Spyrou" housed at l'Espace de l'Homme de Spy (EHoS) museum.

Use of embedded strain gages for the in-vitro study of proximal tibial cancellous bone deformation during knee flexion-extension movement: development, reproducibility and preliminary results of feasibility after frontal low femoral osteotomy

Background

This paper reports the development of an in-vitro technique allowing quantification of relative (not absolute) deformations measured at the level of the cancellous bone of the tibial proximal epiphysis (CB_TPE) during knee flexion-extension. This method has been developed to allow a future study of the effects of low femoral osteotomies consequence on the CB_TPE.

Methods

Six strain gages were encapsulated in an epoxy resin solution to form, after resin polymerisation, six measurement elements (ME). The latter were inserted into the CB_TPE of six unembalmed specimens, just below the tibial plateau. Knee motion data were collected by three-dimensional (3D) electrogoniometry during several cycles of knee flexion-extension. Intra- and inter-observer reproducibility was estimated on one specimen for all MEs. Intra-specimen repeatability was calculated to determine specimen's variability and the error of measurement. A varum and valgum chirurgical procedure was realised on another specimen to observed CB_TPE deformation after these kind of procedure.

Results

Average intra-observer variation of the deformation ranged from 8% to 9% (mean coefficient of variation, MCV) respectively for extension and flexion movement. The coefficient of multiple correlations (CMC) ranged from 0.93 to 0.96 for flexion and extension. No phase shift of maximum strain peaks was observed. Inter-observer MCV averaged 23% and 28% for flexion and extension. The CMC were 0.82 and 0.87 respectively for extension and flexion. For the intra-specimen repeatability, the average of mean RMS difference and the mean ICC were calculated only for flexion movement. The mean RMS variability ranged from 7 to 10% and the mean ICC was 0.98 (0.95 - 0.99). A Pearson's correlation coefficient was calculated showing that RMS was independent of signal intensity. For the chirurgical procedure, valgum and varum deviation seems be in agree with the frontal misalignment theory.

Conclusions

Results show that the methodology is reproducible within a range of 10%. This method has been developed to allow analysis the indirect reflect of deformation variations in CB_TPE before and after distal femoral osteotomies. The first results of the valgum and varum deformation show that our methodology allows this kind of measurement and are encourageant for latter studies. It will therefore allow quantification and enhance the understanding of the effects of this kind of surgery on the CB_TPE loading.

Structural behaviour and strain distribution of the long bones of the human lower limbs

Although stiffness and strength of lower limb bones have been investigated in the past, information is not complete. While the femur has been extensively investigated, little information is available about the strain distribution in the tibia, and the fibula has not been tested in vitro. This study aimed at improving the understanding of the biomechanics of lower limb bones by: (i) measuring the stiffness and strain distributions of the different low limb bones; (ii) assessing the effect of viscoelasticity in whole bones within a physiological range of strain-rates; (iii) assessing the difference in the behaviour in relation to opposite directions of bending and torsion. The structural stiffness and strain distribution of paired femurs, tibias and fibulas from two donors were measured. Each region investigated of each bone was instrumented with 8-16 triaxial strain gauges (over 600 grids in total). Each bone was subjected to 6-12 different loading configurations. Tests were replicated at two different loading speeds covering the physiological range of strain-rates. Viscoelasticity did not have any pronounced effect on the structural stiffness and strain distribution, in the physiological range of loading rates explored in this study. The stiffness and strain distribution varied greatly between bone segments, but also between directions of loading. Different stiffness and strain distributions were observed when opposite directions of torque or opposite directions of bending (in the same plane) were applied. To our knowledge, this study represents the most extensive collection of whole-bone biomechanical properties of lower limb bones.

In vitro 3D-kinematics of the upper cervical spine: helical axis and simulation for axial rotation and flexion extension

PURPOSE

Registration of 3D-anatomical model and kinematics data is reported to be an accurate method to provide 3D-joint simulation. We applied this approach to discrete kinematics analysis of upper cervical spine (UCS) during axial rotation (AR) and flexion extension (FE) to create anatomical models with movement simulation including helical axis.

METHODS

Kinematics and CT imaging data were sampled in ten anatomical specimens. Using technical and anatomical marker digitizing, spatial position of segments was computed for five discrete positions of AR and FE using a 3D-digitizer. Computerized tomography was used to create anatomical models and to assure kinematics and imaging data registration for simulation. Kinematics was processed using orientation vector and helical axis (HA) computation.

RESULTS

Maximal standard error on marker digitizing was 0.47 mm. Range of motion and coupled movement during AR was in agreement with previous in vitro studies. HA location and orientation have shown low variation at the occipitoaxial and atlantoaxial levels for FE and AR, respectively.

CONCLUSIONS

We developed a protocol to create UCS anatomical model simulations including three-dimensional discrete kinematics, using previously validated methods. In this study, simultaneous segmental movement simulation and display of HA variations was shown to be feasible. Although partially confirming previous results, helical axis computation showed variations of motion patterns dependent on movement, level and specimen. Further in vivo investigations are needed to confirm relevance of this method in the clinical field.

The effects of embalming using a 4% formalin solution on the compressive mechanical properties of human cortical bone

BACKGROUND

The use of formalin fixed bone tissue is often avoided because of its assumed influence on the mechanical properties of bone. Fixed bone tissue would minimise biological risks and eliminate preservation issues for long duration experimental tests. This study aimed to determine the short- and long-term effects of embalming, using a solution with 4% formalin concentration, on the mechanical properties of human cortical bone.

METHODS

Three-millimetre cylindrical specimens of human cortical bone were extracted from two femoral diaphyses and divided in four groups. The first group was used as control, the remaining three groups were left in the embalming solution for 48 h, 4 week, and 8 week, respectively. Compressive mechanical properties, hardness and ash density were assessed. The last was used to check the homogeneity among the four groups.

FINDINGS

No significant differences were found among the four groups in yield stress, ultimate stress and hardness. The specimens stored for 8 week in the embalming solution had significant lower Young's modulus (-24%), higher yield strain (+20%) and ultimate strain (+53%) compared to the other groups.

INTERPRETATION

On a short-term perspective, embalming did not affect the compressive mechanical properties, nor hardness of human cortical bone, whereas a long-term preservation (8 week) did significantly affect Young's modulus, yield strain and ultimate strain in compression. Preserving bone segments for up to 4 week in an embalming solution with low formalin concentration seems to be an interesting alternative when collecting and/or managing fresh or fresh-frozen bone segments for biomechanical experiments is not possible.

Multiscale modelling of the skeleton for the prediction of the risk of fracture

BACKGROUND

The development of a multiscale model of the human musculoskeletal system able to accurately predict the risk of bone fracture is still a grand challenge. The aim of this paper is to present the Living Human Project, to describe the final system and to review the achievements obtained so far. The Living Human musculoskeletal supermodel is conceived as the interconnection of five interdependent sub-models: the continuum, the boundary condition, the constitutive equation, the remodelling history and the failure criterion sub-models.

METHODS

Methods are available to develop accurate subject-specific finite element models of bones that can incorporate the subject's tissue-density distribution and empirically derived constitutive laws. Anatomo-functional musculoskeletal models can be registered with gait analysis data to predict muscle and joint forces acting on the patient's skeleton during gait. These are the boundary conditions for the continuum models that showed an average error of 12% in the prediction of the failure load. Still, the entire supermodel is defined as a collection of procedural macros to predict the risk of fracture and should be improved.

FINDINGS

Even with these limitations, the organ-level model already found some clinically relevant applications, especially in the analysis of joint prostheses. Also, the body-organ level multiscale model finds some clinical applications in paediatric skeletal oncology. The tissue- and the cell-level models are not yet fully validated. Thus, they cannot be safely used in clinical applications.

INTERPRETATION

The continuum sub-model is the most mature model available. More powerful methods are needed for the generation of anatomo-functional musculoskeletal models. Muscle force prediction should be improved, investigating new probabilistic approaches to identify the neuro-motor strategy. The changes of the tissue properties in the various regions of the skeleton and predictive remodelling models should be included. An adequate information technology infrastructure should be developed to support collaborative work and integration of different sub-models.

Multimod Data Manager: a tool for data fusion

Nowadays biomedical engineers regularly have to combine data from multiple medical imaging modalities, biomedical measurements and computer simulations and this can demand the knowledge of many specialised software tools. Acquiring this knowledge to the depth necessary to perform the various tasks can require considerable time and thus divert the researcher from addressing the actual biomedical problems. The aim of the present study is to describe a new application called the Multimod Data Manager, distributed as a freeware, which provides the end user with a fully integrated environment for the fusion and manipulation of all biomedical data. The Multimod Data Manager is generated using a software application framework, called the Multimod Application Framework, which is specifically designed to support the rapid development of computer aided medicine applications. To understand the general logic of the Data Manager, we first introduce the framework from which it is derived. We then illustrate its use by an example--the development of a complete subject-specific musculo-skeletal model of the lower limb from the Visible Human medical imaging data to be used for predicting the stresses in the skeleton during gait. While the Data Manager is clearly still only at the prototype stage, we believe that it is already capable of being used to solve a large number of problems common to many biomedical engineering activities.

Imaging assessment of thoracic outlet syndrome

The thoracic outlet includes three compartments (the interscalene triangle, costoclavicular space, and retropectoralis minor space), which extend from the cervical spine and mediastinum to the lower border of the pectoralis minor muscle. Dynamically induced compression of the neural, arterial, or venous structures crossing these compartments leads to thoracic outlet syndrome (TOS). The diagnosis is based on the results of clinical evaluation, particularly if symptoms can be reproduced when various dynamic maneuvers, including elevation of the arm, are undertaken. However, clinical diagnosis is often difficult; thus, the use of imaging is required to demonstrate neurovascular compression and to determine the nature and location of the structure undergoing compression and the structure producing the compression. Cervical plain radiography should be performed first to assess for bone abnormalities and to narrow the differential diagnosis. Computed tomographic (CT) angiography or magnetic resonance (MR) imaging performed in association with postural maneuvers is helpful in analyzing the dynamically induced compression. B-mode and color duplex ultrasonography (US) are good supplementary tools for assessment of vessel compression in association with postural maneuvers, especially in cases with positive clinical features of TOS but negative features of TOS at CT and MR imaging. US may also allow analysis of the brachial plexus. However, MR imaging remains the method of choice when searching for neurologic compression.

Low-dose computed tomography: a solution for in vivo medical imaging and accurate patient-specific 3D bone modeling?

BACKGROUND

The number of in vivo clinical biomedical experiments based on computed tomography is increasing. International radiation-protection bodies are promoting the use of low-dose computed tomography to reduce radiation absorption by the subject undergoing imaging. On the other hand no data exist in the literature to quantify whether or not low-dose computed tomography would lead to a decrease of result quality when used for three-dimensional bone modeling and related measurements.

METHODS

This paper aimed at finding a consensus between minimal X-ray radiation of the subject, and satisfactory image data quality, especially for accurate three-dimensional bone modeling. Several standard computed tomography and low-dose computed tomography sequences were analyzed in three tests and statistically compared.

FINDINGS

Absence of significant difference between standard and low-dose computed sequences indicated that the low-dose setting would not produce less accurate three-dimensional models, while it decreased the effective X-ray dose up to 90% compared to standard settings.

INTERPRETATION

Low-dose computed tomography seems suitable for accurate three-dimensional bone modeling, while the related effective X-ray radiation is low. Such setting is therefore advised for any in vivo medical imaging aiming to collect bone data.

In Vivo Registration of Both Electrogoniometry and Medical Imaging: Development and Application on the Ankle Joint Complex

An in vivo method for joint kinematics visualization and analysis is described. Low-dose computed tomography allowed three-dimensional joint modeling, and electrogoniometry collected joint kinematic data. Data registration occurred using palpated anatomical landmarks to obtain interactive computer joint simulation. The method was applied on one volunteer's ankle, and reproducibility was tested (maximal discrepancy: 3.6 deg and 5.5 mm for rotation and translation respectively).

Double-step registration of in vivo stereophotogrammetry with both in vitro 6-DOFs electrogoniometry and CT medical imaging

Standard registration techniques of bone morphology to motion analysis data often lead to unsatisfactory motion simulation because of discrepancies during the location of anatomical landmarks in the datasets. This paper describes an iterative registration method of a three-dimensional (3D) skeletal model with both 6 degrees-of-freedom joint kinematics and standard motion analysis data. The method is demonstrated in this paper on the lower limb. The method includes two steps. A primary registration allowed synchronization of in vitro kinematics of the knee and ankle joints using flexion/extension angles from in vivo gait analysis. Results from primary registration were then improved by a so-called advanced registration, which integrated external constraints obtained from experimental gait pre-knowledge. One cadaver specimen was analyzed to obtain both joint kinematics of knee and ankle joints using 3D electrogoniometry, and 3D bone morphology from medical imaging data. These data were registered with motion analysis data from a volunteer during the execution of locomotor tasks. Computer graphics output was implemented to visualize the results for a motion of sitting on a chair. Final registration results allowed the observation of both in vivo motion data and joint kinematics from the synchronized specimen data. The method improved interpretation of gait analysis data, thanks to the combination of realistic 3D bone models and joint mechanism. This method should be of interest both for research in gait analysis and medical education. Validation of the overall method was performed using RMS of the differences between bone poses estimated after registration and original data from motion analysis.

Calibration and validation of 6 DOFs instrumented spatial linkage for biomechanical applications. A practical approach

A method for both calibration and validation of a 6 DOF electrogoniometer is presented. A 6 Revolute Instrumented Spatial Linkage (6R-ISL) and a three-dimensional digitizer (3DD) were used simultaneously to collect both static and continuous poses of unconstrained or constrained motions. Validation occurred using a calibrated ball-and-socket joint. A parametrical model of the 6R-ISL (i.e. Virtual Goniometer or VG) was designed using a standard multibody system geometry. Two approaches were used to adjust the VG parameters: a parametrical adjustment of the VG linkage geometry, and a functional adjustment of the potentiometer calibration curves (angle-voltage) in a predefined range of motion. After calibration, 6R-ISL accuracy was better than 1 mm and 1 degrees for translation and orientation, respectively. The functional method presented in this paper can be suggested as a practical approach, which allows on-line checking and calibration of 6R-ISL within the specific range of interest of a particular anatomical joint. In addition, improving the potentiometer calibration curves was less time consuming than the parametrical adjustment.

Development of multimedia learning modules for teaching human anatomy: application to osteology and functional anatomy

Computer-assisted learning (CAL) is growing quickly within academic programs. Although the anatomical commercial packages that are available for this learning have attractive advantages, they also have drawbacks: they are frequently not in the local language of the students, they do not perfectly answer the needs of the local academic program, and their cost is frequently more than students can afford. This study describes a relatively inexpensive method to create CAL tutorials, whose content can be fully customized to local academic needs in terms of both program and language. The study describes its use in creating multimedia learning modules (MLMs) about Osteology and joint kinematics. The pedagogical content in these modules was collected from objective experiments to give students the opportunity to access new scientific knowledge during their education. It can be replaced, as desired, by almost any content due to the flexibility of the production method. Each MLM consists of two complementary subelements: a multimedia theoretical lecture and a three-dimensional interactive laboratory. Such MLMs are in use at both the University of Brussels (ULB) and the National University of Rwanda (NUR). The development of this work was part of the VAKHUM project, and the pedagogical validation is currently being performed as part of the MULTIMOD project.