Gracilis and semitendinosus moment arm decreased by fascial tissue release after hamstring harvesting surgery: a key parameter to understand the peak torque obtained to a shallow angle of the knee.

PURPOSE: Semitendinosus and gracilis muscles whose tendons are used in surgical reconstruction of the anterior cruciate ligament maintain their contractile ability, but the peak torque angle of hamstring muscles shifted to a shallow angle postoperatively. The goal was to quantify the influence of the myofascial structures on instantaneous moment arms of knee muscles to attempt explaining the above-mentioned post-surgical observations. METHODS: Hamstring harvesting procedures were performed by a senior orthopaedic surgeon on seven lower limbs from fresh-frozen specimens. Femoro-tibial kinematics and tendons excursion were simultaneously recorded at each step of the surgery. RESULTS: No significant difference was demonstrated for instantaneous moment arm of gracilis during anterior cruciate ligament surgery (84% of the maximum intact values; P ≥ 0.05). The first significant semitendinosus moment arm decrease was observed after tendon harvesting (61% of the maximum intact values; p ≤ 0.005). After hamstring harvesting, the maximum and minimum moment arm (both gracilis and semi tendinosus) shifted to a shallow angle and 90°, respectively. CONCLUSION: Moment arm modifications by paratenons and the loose connective tissue release are essential to understand the peak torque obtained to a shallow angle. LEVEL OF EVIDENCE: Basic science study, biomechanics.

Prediction of the drilling path to surgically pin the femoral neck from the spatial location of pelvic and femoral anatomical landmarks: A cadaver validation study.

Several clinical applications rely on accurate guiding information when drilling along the femoral neck (e.g., pin insertion in case of neck fracture). Currently, applications rely on real-time X-ray imaging, which results in irradiation issues for the surgeon conducting the operation. The goal of this paper was to develop an X-ray-free method that would allow for a pathway to be drilled between the lateral aspect of the femoral diaphysis (the so-called piercing point), the femoral neck and the head centres. The method is based on on-the-fly computational predictions relying on a biomechanical database that includes morphological data related to the femoral neck and head and various palpable anatomical landmarks located on the pelvis and the femoral bone. From the spatial location of the anatomical landmarks, scalable multiple regressions allow for the prediction of the most optimal drilling pathway. The method has been entirely validated using in vitro experiments that reproduce surgical conditions. Further, a surgical ancillary prototype that integrates the method of guiding the pin drilling has been developed and used during in vitro and in situ validation using nine hip joints. Pin insertion was controlled after drilling using medical imaging and show successful result for each of the nine trials. The mean accuracy of the estimated hip joint centre and neck orientation was 6.0 ± 2.8mm and 7.1 ± 3.8°, respectively.

[Sports-related concussions: are we (fully) aware of the consequences?]. / Commotions cérébrales dans le sport: est-on (pleinement) conscient des conséquences?

Contact sports and sports with high risk of head traumatism are increasingly becoming more popular. This trend leads to a 60% increase of sport-related concussions in the decade. It is therefore important to summarize the current knowledge in this field (diagnosis, risk factors...) in order to help clinicians to improve this pathology management. Short and long term consequences are too often minimized by clinicians, while related clinical disorders should not be neglected (e.g. headaches, cognitive troubles, vestibular troubles, depression...). Complications risks are directly linked to the number of concussions or if patients return to play before complete recovery. Correct knowledge of symptoms and of the various assessment tests are consequently therefore important to know in order identity and tackle long term complications of sport-related concussions.

Tendon and fascial structure contributions to knee muscle excursions and knee joint displacement.

BACKGROUND: Semitendinosus and gracilis muscles whose tendons are used in surgical reconstruction of the anterior cruciate ligament maintain their contractile ability, and a limited decrease of hamstring muscles force is observed postoperatively despite important changes. The goal was to quantify the influence of the myofascial structures on excursions and moment arms of knee muscles to attempt explaining the above-mentioned post-surgical observations. METHODS: Hamstring harvesting procedures were performed by a senior orthopaedic surgeon on seven lower limbs from fresh-frozen specimens. Femoro-tibial kinematics and tendons excursion were simultaneously recorded at each steps of the surgery. FINDINGS: No significant difference was demonstrated for excursions and moment arms after tenotomies and gracilis tendon harvesting (P≥0.05). The first significant semitendinosus excursion (P<1.17×10(-4)) and moment arm (P<6.88×10(-5)) decrease was observed after semitendinosus tendon harvesting (46% of the initial excursion). INTERPRETATION: Gracilis and semitendinosus myofascial pathway is crucial for force transmission towards the knee joint.

Can serious games be incorporated with conventional treatment of children with cerebral palsy? A review.

The use of video games in rehabilitation is becoming more popular to clinicians. These games are embedded in off-the-shelf commercial entertainment applications or especially-developed for clinical purposes. Treatment of cerebral palsy (CP) children is a challenging task for clinicians. Lack of motivation and progress monitoring are two important factors clinicians need to deal with. The use of serious games (SG), sometimes referred to as Virtual Rehabilitation (VR), could therefore be an interesting adjuvant to conventional treatment for these patients. This is however a new discipline and many scientific issues remain to be solved. The aim of this paper is to describe available conventional treatment for CP children together with the level of evidence of each approach. A systematic review of the use of SG in rehabilitation is then conducted. 31 papers (7 randomized clinical trials, 16 cohort studies and 8 single-cases studies) were selected and analyzed, and their level of evidence compared to the conventional treatment. These studies reported outcomes for 352 patients. In summary, this review shows that it is difficult to compare those studies despite the large amount of patients. This is due to the lack of standardization in patient rehabilitation strategy and to the use of various clinical scales and scores. This non-standardization in patient follow-up between previously-published works make evidence-based conclusions difficult to obtain in order to support these techniques objectively. The use of SG for rehabilitation purposes currently meets similar issues. This paper proposes standardization strategies in order to improve treatment comparison and SG use in rehabilitation.

Determination of the precision and accuracy of morphological measurements using the Kinect™ sensor: comparison with standard stereophotogrammetry.

The recent availability of the Kinect™ sensor, a low-cost Markerless Motion Capture (MMC) system, could give new and interesting insights into ergonomics (e.g. the creation of a morphological database). Extensive validation of this system is still missing. The aim of the study was to determine if the Kinect™ sensor can be used as an easy, cheap and fast tool to conduct morphology estimation. A total of 48 subjects were analysed using MMC. Results were compared with measurements obtained from a high-resolution stereophotogrammetric system, a marker-based system (MBS). Differences between MMC and MBS were found; however, these differences were systematically correlated and enabled regression equations to be obtained to correct MMC results. After correction, final results were in agreement with MBS data (p = 0.99). Results show that measurements were reproducible and precise after applying regression equations. Kinect™ sensors-based systems therefore seem to be suitable for use as fast and reliable tools to estimate morphology. Practitioner Summary: The Kinect™ sensor could eventually be used for fast morphology estimation as a body scanner. This paper presents an extensive validation of this device for anthropometric measurements in comparison to manual measurements and stereophotogrammetric devices. The accuracy is dependent on the segment studied but the reproducibility is excellent.

Validity and reliability of the Kinect within functional assessment activities: comparison with standard stereophotogrammetry.

The recent availability of the Kinect™ sensor, a cost-effective markerless motion capture system (MLS), offers interesting possibilities in clinical functional analysis and rehabilitation. However, neither validity nor reproducibility of this device is known yet. These two parameters were evaluated in this study. Forty-eight volunteers performed shoulder abduction, elbow flexion, hip abduction and knee flexion motions; the same protocol was repeated one week later to evaluate reproducibility. Movements were simultaneously recorded by the Kinect (with Microsoft Kinect SDK v.1.5) MLS and a traditional marker-based stereophotogrammetry system (MBS). Considering the MBS as reference, discrepancies between MLS and MBS were evaluated by comparing the range of motion (ROM) between both systems. MLS reproducibility was found to be statistically similar to MBS results for the four exercises. Measured ROMs however were found different between the systems.

Model-based approach for human kinematics reconstruction from markerless and marker-based motion analysis systems.

Modeling tools related to the musculoskeletal system have been previously developed. However, the integration of the real underlying functional joint behavior is lacking and therefore available kinematic models do not reasonably replicate individual human motion. In order to improve our understanding of the relationships between muscle behavior, i.e. excursion and motion data, modeling tools must guarantee that the model of joint kinematics is correctly validated to ensure meaningful muscle behavior interpretation. This paper presents a model-based method that allows fusing accurate joint kinematic information with motion analysis data collected using either marker-based stereophotogrammetry (MBS) (i.e. bone displacement collected from reflective markers fixed on the subject's skin) or markerless single-camera (MLS) hardware. This paper describes a model-based approach (MBA) for human motion data reconstruction by a scalable registration method for combining joint physiological kinematics with limb segment poses. The presented results and kinematics analysis show that model-based MBS and MLS methods lead to physiologically-acceptable human kinematics. The proposed method is therefore available for further exploitation of the underlying model that can then be used for further modeling, the quality of which will depend on the underlying kinematic model.

[Clinical examination of children with cerebral palsy: is there a consensus between clinicians?]. / Examen clinique de l'enfant infirme moteur cérébral: existe-t-il un consensus entre les praticiens?

Diagnosis and most of all classification of children with cerebral palsy (CP) remain a challenge for clinicians. To help them in this process, clinicians can rely on several clinical testing procedures as well as complementary investigations. The goal of this study was to determine which clinical tests found in the literature are the most frequently used in common practice in Belgium. Forty tests have been found in the literature. They have been sorted into five different categories: quantitative evaluation of motor function, spasticity evaluation, orthopaedic testing, upper limb evaluation and complementary investigations. Seven clinicians (five medical doctors and two physiotherapists) with a mean experience of sixteen years with CP children answered the questionnaire. Concerning the quantitative evaluation of motor function the most used tests are: Gross Motor Function Classification System, Manual Ability Classification System and the Pediatric Evaluation of Disability Inventory (PEDI). As regards spasticity, Ashworth scale is more frequently used than Tardieu test. No trend currently exist for the upper limb evaluation, but it was noted that these tests are rarely used in clinical practice. We observed a significant use of gait analysis at diagnosis and follow-up of CP children. We conclude that there are large differences between clinicians for clinical examination of CP children. This lack of consensus makes patient data comparison difficult between clinical centers. This seems to indicate that a homogenization effort should be organized if one wishes to better stimulate collaborations between centers.

In vitro biomechanical study of femoral torsion disorders: effect on moment arms of thigh muscles.

BACKGROUND: Lower limb torsion disorders have been considered as a factor inducing gonarthrosis and the three-dimensional effect of the surgical correction is not well reported yet. This paper reports an in vitro study aiming at quantifying the relationships between experimental femoral torsion disorders and moment arms of thigh muscles. METHODS: Five unembalmed lower limbs were used and fixed on an experimental jig. Muscles were loaded and 6 Linear Variable Differential Transformers were used to measure tendon excursions. Experimental osteotomies were performed to simulate torsions by steps of 6° up to 18°. Moment arms of the main thigh muscles were estimated by the tendon excursion method during knee flexion. FINDINGS: Moment arms of the tensor of fascia latae, the gracilis and the semitendinosus were significantly influenced by experimental conditions while the rectus femoris, the biceps femoris and the semimembranosus did not show modifications. Medial femoral torsion decreased the moment arm of both the gracilis and the semimembranosus. Opposite changes were observed during lateral femoral torsion. The moment arm of the tensor of fascia latae decreased significantly after 30° of knee flexion for 18° of medial femoral torsion. INTERPRETATION: Our results showed that medial and lateral femoral torsion disorders induced alterations of the moment arms of the muscles located medially to the knee joint when applied in aligned lower limbs. These results highlight a potential clinical relevance of the effect of femoral torsion alterations on moment arms of muscles of the thigh which may be related, with knee kinematics modifications, to the development of long-term knee disease.

In vitro biomechanical study of femoral torsion disorders: effect on femoro-tibial kinematics.

BACKGROUND: Gonarthrosis is a degenerative disease mainly found in elderly persons. Frontal plane deviations are known to induce lateral and medial gonarthrosis. Nevertheless, patients suffer from gonarthrosis without frontal deviations. Lower limb torsions disorders have been considered as a factor inducing lateral and medial gonarthrosis. This paper reports an in vitro study aiming at quantifying the relationships between experimental femoral torsion disorders and femoro-tibial kinematics. METHODS: Five fresh-frozen lower limbs were used. Specimens were fixed on an experimental jig and muscles were loaded. A six-degree-of-freedom Instrumented Spatial Linkage was used to measure femoro-tibial kinematics. Experimental femoral osteotomies were performed to simulate various degrees of medial and lateral torsion. Internal tibial rotation, abduction/adduction and proximo-distal, medio-lateral and antero-posterior translations were measured during knee flexion. FINDINGS: Internal tibial rotation and abduction/adduction were significantly influenced (P<0.001) by femoral torsion disorder conditions. Medial femoral torsion increased tibial adduction and decreased internal rotation during knee flexion. Opposite changes were observed during lateral femoral torsion. Concerning translations, medial femoral torsion induced a significant (P<0.05) decrease of medial translation and inversely for lateral femoral torsion. No interactions between femoral torsion disorders and range of motion were observed. INTERPRETATION: Our results showed that medial and lateral femoral torsion disorders induced alterations of femoro-tibial kinematics when applied in normally aligned lower limbs. These results highlight a potential clinical relevance of the effect of femoral torsion alterations on knee kinematics that may be related to the development of long-term knee disease.

[Immunohistochemical study of Dlx1 and Msx1 expression during cephalic development of Dumbo and Wistar rats. Correlation with morphological data]. / Étude immuno-histochimique de l'expression des protéines Dlx1 et Msx1 durant la céphalogenèse des rats Wistar et Dumbo Corrélation avec les données morphologiques.

The Dumbo rat is characterized by a short snout, low ears and relative hypoplasia of maxillar and zygomatic bones. It corresponds to an autosomal recessive genotype. Previous study demonstrated a global deficit of Dlx1 and Msx1 genes expression in comparison to Wistar embryos as considered as control animals. We performed a histological study of cephalic development of Dumbo rats compared to Wistar embryos and an immunohistochemical analysis of Dlx1 and Msx1 protein expression during cephalogenesis. Our data indicate that the pattern of expression of both genes is similar in both strains, but that quantitative differences in gene expression can be the result of delayed organogenesis in Dumbo rat in comparison to Wistar. Some data about gene expressions are discussed at the light of the postulated function of Dlx1 and Msx1 in cephalic development.

[Reconstruction of the knee anterior cruciate ligament: single or double bundle?]. / Reconstruction du ligament croisé antérieur du genou: simple ou double faisceau?

Anatomical and biomechanical studies have shown that the anterior cruciate ligament (ACL) consists of two distinct bundles, the anteromedial (AM) and posterolateral. Each bundle has its specific role during the motion of the knee. ACL reconstruction techniques have focused on the restauration of the anteroposterior stability by substituting the more isometric AM bundle. Although these ligamentoplasties provide overall good results, in the last ten years double-bundle ACL reconstruction techniques have been developed, to better replicate the ligament anatomy. Despite the growing number of published studies, including randomized controlled trials comparing single bundle and double bundle reconstructions, there is still a lack of evidence of any superiority of the double-bundle technique. Furthermore, many series are criticized for their poor assessement of rotational stability, using most of the time subjective pivot shift clinical testing. Among the methods available to measure tibial rotation, 3-D optoelectronic evaluation is an attractive tool and has been used in some studies reporting rotational mesurements after ACL single-bundle reconstruction. Our Department of Orthopaedics and Traumatology has been using double-bundle techniques for a few years. We conducted a preliminary prospective randomized study, in order to compare single and double-bundle techniques by clinical and optoelectronic evaluations.

Femur shape prediction by multiple regression based on quadric surface fitting.

Quadric surface fitting of joint surface areas is often performed to allow further processing of joint component size, location and orientation (pose), or even to determine soft tissue wrapping by collision detection and muscle moment arm evaluation. This study aimed to determine, for the femoral bone, if the position of its morphological joint centers and the shape morphology could be approximated using regression methods with satisfactory accuracy from a limited amount of palpable anatomical landmarks found on the femoral bone surface. The main aim of this paper is the description of the pipeline allowing on one hand the data collection and database storage of femoral bone characteristics, and on the other hand the determination of regression relationships from the available database. The femoral bone components analyzed in this study included the diaphysis, all joint surfaces (shape, location and orientation of the head, condyles and femoro-patellar surface) and their respective spatial relationships (e.g., cervico-diaphyseal angle, cervico-bicondylar angle, intercondylar angle, etc.). A total of 36 morphological characteristics are presented and can be estimated by regression method in in-vivo applications from the spatial location of 3 anatomical landmarks (lateral epicondyle, medial epicondyle and greater trochanter) located on the individual under investigation. The method does not require any a-priori knowledge on the functional aspect of the joint. In-vivo and in-vitro validations have been performed using data collected from medical imaging by virtual palpation and data collected directly on a volunteer using manual palpation through soft tissue. The prediction accuracy for most of the 36 femoral characteristics determined from virtual palpation was satisfactory, mean (SD) distance and orientation errors were 2.7(2.5)mm and 6.8(2.7)°, respectively. Manual palpation data allowed good accuracy for most femoral features, mean (SD) distance and orientation errors were 4.5(5.2)mm and 7.5(5.3)°, respectively. Only the in-vivo location estimation of the femoral head was worse (position error=23.2mm). In conclusion, results seem to show that the method allows in-vivo femoral joint shape prediction and could be used for further development (e.g., surface collision, muscle wrapping, muscle moment arm estimation, joint surface dimensions, etc.) in gait analysis-related applications.

The Dumbo rat mutant: a cytogenetic, morphologic and sagittal morphometric analysis.

OBJECTIVE: To study the possibility of use Dumbo rat as, experimental model for understanding abnormal craniofacial development. DESIGN: We investigated craniofacial morphogenesis in the Dumbo rat by morphologic and morphometric technics. We also performed a cytogenetic study of this rat. Wistar strain was considered as control. For morphologic and morphometric studies, we used Dumbo and Wistar embryos at E15 to 21. We stained these embryos in toto with alcian blue and alizarin red. The skeletons of the embryos were examined and drawn under a Lucida camera, and the following sagittal measurements were taken: zygomatic length and thickness, length of the mandible and its anterior and posterior thicknesses, length of the maxillary, and petrous bone height. Statistical analyses were realized using Mann Whitney test in SPSS. For cytogenetic study, chromosome spreads were prepared from lymphocyte cultures obtained from the blood of adult rats of both strains. RESULTS: The Dumbo embryos exhibited hypoplasia of the zygomatic, maxillar and mandibular bones, and micrognathia, evoking some human dysmorphogenesis . Moreover, the position of the preliminary ear was abnormally low. The differences in the measurements of the craniofacial structures between the two groups of rats are significant. However, the cytogenetic study did not reveal any differences between the two strains. CONCLUSION: Our data indicate that the considerable morphometric differences between the craniofacial structures of Dumbo and Wistar rats might be due to genetic mutations that are undetectable by chromosome mapping. Further histologic and genetic analyses might contribute to elucidate the early determinism of the Dumbo phenotype.

[Geldanamycin administration reduces the number of HSP86-positive germ cells in the mouse embryo: preliminary results]. / L'administration de geldanamycine réduit le nombre de gonocytes exprimant l'HSP86 chez l'embryon de souris: premiers résultats.

5 mg of Geldanamycin, an inhibitor of stress protein HSP86 which express on mammalian germ cells, were administered to E8 pregnant mice. E17 embryos were removed, and a quantitative analysis of HSP90-immunoreactive cells in the gonad was performed, in comparison to control embryos. First, we observed that the number of germ cells is lower in male than in female embryos, as well in control and experimental embryos. External features of experimental and control embryos did not display any difference. Embryos exposed to geldanamycin exhibit a significant decrease of immunoreactive germ cells. In two embryos, we observed a group of ectopic immunoreactive cells in the pelvic area. We conclude that geldanamycin inhibits germ cells migration, and suggest that this inhibition can lead to ectopic germ cell populations, similar to teratomas.

Precision of shoulder anatomical landmark calibration by two approaches: a CAST-like protocol and a new anatomical palpator method.

The objective of the study was to compare the precision of shoulder anatomical landmark palpation using a CAST-like method and a newly developed anatomical palpator device (called A-Palp) using the forefinger pulp directly. The repeated-measures experimental design included four examiners that twice repeated measurements on eleven scapula and humerus anatomical landmarks during two sessions. Inter-session and inter-examiner precision was determined on volunteers. A-Palp accuracy was obtained from in vitro measurements and using virtual palpation on 3D bone models. Error propagation on the motion representation was also analyzed for a continuous motion of abduction movement performed in the shoulder joint. Palpation results showed that CAST and A-Palp methods lead to similar precision with the Maximal A-Palp calibration error being 1.5mm. In vivo precision of the CAST and A-Palp methods varied between 4mm (inter-session) and 8mm (inter-examiner). Mean propagation of the palpation error on the motion graph representation was 2 degrees and 5 degrees for scapula and humerus, respectively. A-Palp accuracy was 3.6 and 8.1mm for scapula and humerus, respectively. The A-Palp seems promising and could probably become an additional method next to today's marker-based motion analysis systems (i.e., Helen-Hayes configuration, CAST method).

Prediction of joint center location by customizable multiple regressions: application to clavicle, scapula and humerus.

Accurate spatial location of joint center (JC) is a key issue in motion analysis since JC locations are used to define standardized anatomical frames, in which results are represented. Accurate and reproducible JC location is important for data comparison and data exchange. This paper presents a method for JC locations based on the multiple regression algorithms without preliminary assumption on the behavior of the joint-of-interest. Regression equations were obtained from manually palpable ALs on each bone-of-interest. Results are presented for all joint surfaces found on the clavicle, scapula and humeral bone. Mean accuracy errors on the JC locations obtained on dry bones were 5.2+/-2.5 mm for the humeral head, 2.5+/-1.1 mm for the humeral trochlea, 2.3+/-0.9 mm for the humeral capitulum, 8.2+/-3.9 mm for the scapula glenoid cavity, 7.2+/-3.2 mm for the scapular aspect of the acromio-clavicular joint, 3.5+/-1.8mm for the clavicular aspect of the sternoclavicular joint and 3.2+/-1.4 mm for the clavicular aspect of the acromio-clavicular joint. In-vitro and in-vivo validation accuracy was 5.3 and 8.5mm, respectively, for the humeral head center location. Regression coefficients for joint radius dimension and joint surface orientation were also processed and reported in this paper.

Quantified relationships of the radial nerve with the radial groove and selected humeral landmarks.

Anatomical relationships between the radial nerve, the deltoid muscle insertions and several bony landmarks have been investigated to assess the feasibility of surgical transfer of the deltoid transfer during humeral osteotomy. Eleven embalmed human specimens were dissected. Each specimen included the whole thorax, both shoulders and upper limbs. Spatial position of the radial nerve along the radial groove, the deltoid muscle, and several anatomical landmarks was digitised using a three-dimensional (3D) digitiser. Sixteen distances and one angle characterizing the relationships between the path of the radial nerve and the landmarks were processed. Results showed that the average distance between the emergence of the radial nerve from the lateral intermuscular septum and the most distal insertion point of the deltoid muscle on the humeral bone shaft was 47.6 +/- 18.5 mm. The angle between a line extending from the entry of the radial nerve into the radial sulcus and its point of emergence (REN-REM line), and on the other hand a line running from the radial emergence and the deltoid muscle tip (REM-DELTIP line) was in average 23.5 +/- 6.7 degrees . The length of four lines running perpendicular to REM-DELTIP and crossing each quarter of the REN-REM line were interpolated. The length of these four lines was, from proximal to distal, 31.3 +/- 11.5 mm; 23.0 +/- 7.8 mm; 16.5 +/- 6.2 mm; and 7.6 +/- 2.6 mm, respectively. These results described in a quantitative way the path of the radial nerve in respect to the humeral bone and the deltoid muscle. These data will be used for further development of a humeral osteotomy protocol taking into account the spatial position of the radial nerve to orientate safely the surgical tools used to cut the humeral shaft.

[Learning strategies and anatomy teaching in the Pôle Universitaire Européen Bruxelles-Wallonie]. / Stratégies d'apprentissage et enseignement d'anatomie humaine au sein du Pô1e Universitaire Européen Bruxelles-Wallonie.

In order to compare the learning strategies associated to human anatomy courses in student of first, second and third year in medicine, first year in medical biology technologists and first year in nursing, we distributed a questionnaire to the students. The results revealed some similarities, but also several differences, in relationship with local conditions, the content of the courses, and specificities of different student groups, especially in their study choice. Paradoxically, the integration of medical imaging in medical students seems to be difficult, and the medical students are reticent to use another body to ingrate anatomy, although surface anatomy constitutes a part of the anatomical program. This restriction is absent in nursing. These results constitute important data in the field of cognitive research, but also should be useful to improve our pedagogic strategy in specific populations.