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.

[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.

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.

[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.

[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.

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.

[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.

[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.

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.

[Changes in knee kinematics and quadriceps and hamstrings moment arms after high valgus and varus tibial "dome" osteotomy: An in vitro study]. / Modifications de la cinématique du genou et des bras de levier du quadriceps et des ischio-jambiers après ostéotomie tibiale haute "curviplane" de valgisation ou de varisation: étude in vitro.

PURPOSE OF THE STUDY: Analysis of the correction or over-correction of high valgus and varus tibial osteotomies is generally limited to the frontal plane. Most likely however, the deformation observed radiographically in the frontal plane is simply a one-dimensional expression of a more complex three-dimensional deformation. This might be one of the causes for certain failures after surgery and recurrent problems which are difficult to solve. We proposed using 3D electrogoniometric to measure of the effect of a "dome" osteotomy on patellar and femoro-tibial kinematics and the changes in the moment arms of the knee muscles. MATERIAL AND METHODS: We used five lower limbs harvested from non-fixed cadavers. A "dome" osteotomy was stabilized by external fixation. Three-dimensional analysis of the femoro-tibial and femoro-patellar kinematics was performed using two electrogoniometers with six degrees of freedom. Changes in the lengths of the hamstrings and quadriceps was measured using four LVDT linear variable differential transformers. The muscles lever arms were measured with the tendon excursion method. RESULTS: At 90 degrees flexion, varus osteotomy induced internal rotation while valgus osteotomy induced the opposite effect. Beyond 40 degrees flexion, there was a clear internal rotation of the patella for varus and neutral corrections. Valgus corrections however induced external rotation. The peak lever arm of the quadriceps increased with valgus, while the angle of the peak was higher for varus correction. Valgus appeared to increase the lever arm of the semitendinous. DISCUSSION: Our study demonstrated that the effect of tibial osteotomy is not limited to the frontal plane. Tibial rotations are observed systematically for all corrections in the frontal plane. Varus correction tends to create internal rotation while valgus correction tends to have the opposite effect. Axial correction also affects patellar kinematics. Interanal rotation is induced by varus correction and external rotation by valgus correction. This patellar rotation could result from tibial rotations induced by the different corrections. The loss of the parallelism between the patellar crest and the trochlear groove could produce changes in femoropatellar surface contact and pressure, potentially leading to pain or cartilage degeneration. The maximal value of the quadriceps moment arm appears to increase with valgus. The efficacy of the quadriceps could thus be improved with valgus, potentially increasing extension force. Valgus increases the moment arm, improving limb flexion, while varus correction has the opposite effect. This could explain a loss in flexion amplitude in patients with varus or who underwent varus osteotomy. Tibial osteotomy is designed to correct the deviation solely in the frontal plane but also has effects in all three planes. Further 3D analyses of the morphology and physiology of the knee joint would be needed to better understand the physiological and pathological processes involved.

[Expression of caspase 3 and p53 during physiological apoptosis and apoptosis induced by three teratologic agents during early craniofacial development of the mouse embryo]. / L'expression de la caspase 3 et la protéine p53 au cours de l'apoptose physiologique et induite par 3 agents tératogènes au cours du developpement crânimofacial précoce de l'embryon de souris.

The neural crest-derived mesectoderm gives rise to physiologic apoptosis areas in early vertebrate embryos. Certain teratologic agents increase this phenomenon. The purpose of this work was to detect caspase 3 (which is associated with the apoptosis cascade) and p53 in cell death areas, both during physiological apoptosis and during apoptosis induced by three agents (retinoic acid, methyl-triazene, irradiation). Antibody revelation was performed using the aBC peroxidase kit. Quantifications were also performed on histological sections. We observed caspase 3 uptake on some apoptotic and preapoptotic cells in control embryos, and in the embryos exposed to the three teratogens. Immunoreactivity generally preceded the development of cytological features of apoptosis. However, p53 was expressed only in the embryos exposed to ionizing radiation and methyl-triazene (an alkylating agent), but not significantly in embryos exposed to retinoic acid. The present results throw some light on apoptosis mechanisms in several teratologic conditions.

Moment arm length variations of selected muscles acting on talocrural and subtalar joints during movement: an in vitro study.

The tendon excursion method was applied to estimate the moment arm length of triceps surae, flexor hallucis longus, tibialis posterior, tibialis anterior, peroneus brevis and peroneus longus at talocrural and subtalar joints of 10 anatomical preparations. Orthogonal polynomials were fitted to the tendon excursion data and by derivation with respect to the joint angle, the instantaneous moment arm length for any joint position was evaluated. Both joints were investigated separately. Individual data, the mean moment arm together with the significant moment arm coefficients of the polynomials are presented. Considering their moment arm, the most important plantar flexor were triceps surae, flexor hallucis longus and to a much lesser extent peroneus longus, peroneus brevis and tibialis posterior. Results suggest a partially new insight into the muscle action at the subtalar joint. Although displaying a mean inversion moment arm of about -5.3 mm over the whole range of motion, triceps surae had an inversion moment arm in eversion and an eversion one in inversion. Tibialis posterior exhibited the most important inversion moment arm (-19.1 mm), whereas tibialis anterior had a very low one (-3.8 mm). For some specimens this muscle was found to have an eversion moment arm. Peronei longus and brevis had a nearly identical moment arm at the subtalar joint (21.8 and 20.5 mm).

Registration of 6-DOFs electrogoniometry and CT medical imaging for 3D joint modeling.

The paper describes a method in which two data-collecting systems, medical imaging and electrogoniometry, are combined to allow the accurate and simultaneous modeling of both the spatial kinematics and the morphological surface of a particular joint. The joint of interest (JOI) is attached to a Plexiglas jig that includes four metallic markers defining a local reference system (R(GONIO)) for the kinematics data. Volumetric data of the JOI and the R(GONIO) markers are collected from medical imaging. The spatial location and orientation of the markers in the global reference system (R(CT)) of the medical-imaging environment are obtained by applying object-recognition and classification methods on the image dataset. Segmentation and 3D isosurfacing of the JOI are performed to produce a 3D model including two anatomical objects-the proximal and distal JOI segments. After imaging, one end of a custom-made 3D electrogoniometer is attached to the distal segment of the JOI, and the other end is placed at the R(GONIO) origin; the JOI is displaced and the spatial kinematics data is recorded by the goniometer. After recording, data registration from R(GONIO) to R(CT) occurred prior to simulation. Data analysis was performed using both joint coordinate system (JCS) and instantaneous helical axis (IHA).Finally, the 3D joint model is simulated in real time using the experimental kinematics data. The system is integrated into a computer graphics interface, allowing free manipulation of the 3D scene. The overall accuracy of the method has been validated with two other kinematics data collection methods including a 3D digitizer and interpolation of the kinematics data from discrete positions obtained from medical imaging. Validation has been performed on both superior and inferior radio-ulna joints (i.e. prono-supination motion). Maximal RMS error was 1 degrees and 1.2mm on the helical axis rotation and translation, respectively. Prono-supination of the forearm showed a total rotation of 132 degrees for 0.8mm of translation. The method reproducibility using JCS parameters was in average 1 degrees (maximal deviation=2 degrees ) for rotation, and 1mm (maximal deviation=2mm) for translation. In vitro experiments have been performed on both knee joint and ankle joint. Averaged JCS parameters for the knee were 109 degrees, 17 degrees and 4 degrees for flexion, internal rotation and abduction, respectively. Averaged maximal translation values for the knee were 12, 3 and 4mm posteriorly, medially and proximally, respectively. Averaged JCS parameters for the ankle were 43 degrees, 9 degrees and 3 degrees for plantarflexion, adduction and internal rotation, respectively. Averaged maximal translation values for the ankle were 4, 2 and 1mm anteriorly, medially and proximally, respectively.

Joint kinematics simulation from medical imaging data.

A method for joint kinematics simulation is described. Kinematics parameters are determined from the relative displacement of marker sets placed on anatomical landmarks of surface models generated from medical imaging contour data. The landmarks are identified manually on fingers in multiple positions. A mathematical algorithm was then used to ascertain the kinematics axes of motion of the fingers. Once these axes are located, they are used as the base of a real time interactive simulation of the finger. The entire simulation was accomplished in a high-resolution graphics environment. A full complement of interactive tools (virtual dials and buttons controlled via mouse) was used to enhance the user interface. The development of the system, the model and the advantages and disadvantages of the method are discussed.

Normal global motion of the cervical spine: an electrogoniometric study.

OBJECTIVE: Establishment of a normal database and clinical reference of active global cervical spine motion ranges and patterns using a commercial electrogoniometer. DESIGN: Three-dimensional cervical motion ranges and patterns were analyzed in 250 asymptomatic volunteers. BACKGROUND: In vivo out-of-plane motion patterns of the cervical spine have not yet been reported in large populations, but could be of clinical interest. METHODS: In 250 subjects (aged 14-70 yr), motion range and patterns between the first thoracic vertebra and the head were analyzed for flexion-extension, lateral bending, rotation in neutral sagittal plane position and in full flexion using the CA 6000 Spine Motion Analyzer. RESULTS AND CONCLUSIONS: Average motion range in the sagittal plane was 122 degrees (SD: 18 degrees ). Flexion was slightly more important than extension. Out-of-plane components were negligible. Global bending range averaged 88 degrees (SD: 16 degrees ), left and right bending being comparable. Homolateral rotation was associated to lateral bending. Its extent was approximately 40% of the bending range. Global rotation range in neutral sagittal plane position was 144 degrees (SD: 20 degrees ), without significant difference between right and left rotations. Associated motion components were small. During rotation in flexed head position, global range (134 degrees, SD: 24 degrees ) was comparable to the one in neutral flexion. But heterolateral bending, averaging 60% of the primary motion, was associated to flexed rotation. Significant reduction of all primary (but not conjunct) motions with age were obtained. Sex had no influence on cervical motion range. RELEVANCE: Our results agreed with previous observations, validating the methodology used. They thus constitute reference data of cervical out-of-plane motion for clinical applications.

Global 3D head-trunk kinematics during cervical spine manipulation at different levels.

OBJECTIVE: Determination of the three-dimensional kinematics of the head relative to the upper trunk obtained during a manipulation applied on two different cervical levels and on both sides. DESIGN: Descriptive study performed on 14 asymptomatic volunteers. The range of motion was measured by a 3D electrogoniometer during manipulation executed by the same practitioner. BACKGROUND: Spinal manipulative therapy is a common treatment approach in patients suffering from some spinal disorders. Complications exist; they are thought to be related to the force applied by the practitioner and the range of spinal motion obtained during the manipulation. Yet, little is known about cervical spine motion during manipulation. METHODS: Three dimensional electrogoniometry using a 6 degree-of-freedom spatial linkage fixed between the head and the upper trunk was used to record the pattern of motion and the amplitudes obtained during a manipulation on two cervical levels (C3 and C5) and on left and right sides. On single practitioner applied the same technique to all subjects in a seated position. RESULTS: The side and the spinal level manipulated did not influence 3D ranges of motion. The mean ranges of motion obtained were 30 degrees axial rotation, 46 degrees lateral bending and 2 degrees flexion. A significant difference of the flexion-extension range existed between manipulations with and without audible release. Axial rotation and lateral bending ranges were correlated. Except for lateral bending which was close to active range, the motion ranges obtained during manipulation were well below active range of motion reported in literature. CONCLUSIONS: The results of this study suggest that for the kind of manipulation applied, maximal amplitude between head and trunk does not exceed physiological active range of motion. The amplitude for rotation, which is generally assumed to involve greatest risks for negative side effects, is significantly lower than during active motion. As the study was performed with one practitioner, this result may only be generalized with care. RELEVANCE: In spinal manipulative therapy, extreme range of motion as the result of the forces applied is generally believed to represent a major risk for negative side effects, especially with regard to the cervical spine. With a multiple component technique, amplitudes between head and upper trunk were shown not to differ significantly with regard to the side nor to the spinal level. Recorded ranges of motion did not exceed those reported for active motion in literature.

Analysis of helical axes, pivot and envelope in active wrist circumduction.

OBJECTIVE: To study active wrist circumduction and planar moves, in terms of anatomical angles and envelope and of finite helical axes and mean pivot point. DESIGN: We measured the position of the "mean pivot point" and its mean distance to the axes as anatomical angles in an in vivo full range movement. BACKGROUND: The mean pivot point has been used in in vitro and roentgen stereophotogrammetric studies of wrist kinematics. However, the distribution of "3D centers of rotation" has never been presented in a non-invasive in vivo study. METHODS: A light 6 degrees of freedom electrogoniometer was built and employed in vivo to measure circumduction, flexion-extension and radioulnar deviation on both wrists of twenty one volunteers. RESULTS: Results were in general agreement with previously published ranges of wrist planar motion. The circumduction envelope proved to be a relevant representation of active wrist motion. The "mean pivot point" displayed a relative dispersion in localization of this point. CONCLUSION: The pivot results suggest that the wrist acts as a universal joint but with a non fixed location in the capitate head. The major axis of wrist envelope was not skew. RELEVANCE: The envelope and the precise knowledge of the helical axis pivot and its mean distance to the axes could give precious information on wrist functionality and stability after surgical or conservative treatment.

Morphological effect of electromagnetic stimulation on the skeleton of fetal or newborn mice.

In vitro cultures of limbs from fetuses or newborn mice allow for a strict control of the experimental parameters. Moreover the use of controlateral limbs as a control series avoids inter-individual variations and staining artefacts. The results show that the electromagnetic signal used produces modifications in the morphology and the metabolism of the different components of the bone. The modifications observed in the stimulated limbs are: a thicker proliferative layer of chondrocytes, a better lining up of the trabecula and a better configuration of the cartilage. These modifications are probably due to a change on the components of the cartilaginous matrix. The histochemical demonstration of mucopolysaccharides would probably clarify this matter.

Histochemical modifications induced "in vitro" by electromagnetic stimulation of growing bone tissues.

The histochemical modifications induced on a mouse limb bud culture system by electromagnetic stimulation have been investigated using mucopolysaccharide (MPS) staining methods. An increase in the amount of MPS with cartilage has been observed. This difference is more obvious on the more distal segments of the limb, i.e. on the youngest structures. These observations are correlated with some modifications observed in the enzymatic activities of acid phosphatase and of beta glucuronidase.