Synchronization in reaction-diffusion systems with multiple pacemakers.

Spatially extended oscillatory systems can be entrained by pacemakers, regions that oscillate with a higher frequency than the rest of the medium. Entrainment happens through waves originating at a pacemaker. Typically, biological and chemical media can contain multiple pacemaker regions, which compete with each other. In this paper, we perform a detailed numerical analysis of how wave propagation and synchronization of the medium depend on the properties of these pacemakers. We discuss the influence of the size and intrinsic frequency of pacemakers on the synchronization properties. We also study a system in which the pacemakers are embedded in a medium without any local dynamics. In this case, synchronization occurs if the coupling determined by the distance and diffusion is strong enough. The transition to synchronization is reminiscent of systems of discrete coupled oscillators.

[Intra-articular myxofibrosarcoma of the hip in a 10-year-old child]. / Myxofibrosarcome intra-articulaire de la hanche chez un enfant de 10 ans.

We report a case of intra-articular myxofibrosarcoma with acetabular involvement observed in a 10-Year-old boy. Myxofibrosarcoma is a frequent soft tIssue sarcoma usually observed in elderly subjects. It is extremely rare in children and has not been reported previously before the age of 22 Years. Myxofibrosarcoma is a specific type of soft tIssue tumor. Discussion continues concerning its relation with the myxoid variant of malignant fibrous histiocytoma. The myxoid matrix harbors fibroblastic cells with a curvilinear vessel configuration. Prognosis is good after complete resection and careful surveillance. Local recurrence may occur generally with progression of the tumor stage and risk of later metastasis. This is the first report of an intra-articular localization. We discuss the therapeutic options.

[Subacute osteomyelitis of the acetabulum]. / Ostéomyélite subaiguë de l'acétabulum.

A 15-months-old girl presented an excentration of the hip associated with a defect image of the acetabulum. Arthrography revealed a communication between the hip joint and the acetabular defect. Bacteriological specimens of the articular fluid were negative. The radiographic images were compatible with subacute osteomyelitis. Relative immobilization using an Atlanta abduction devise was undertaken. No medical treatment was prescribed for this adolescent who had received antibiotics for polymicrobial urinary tract infections and for pharyngitis prior to detection of the orthopedic disorder. Outcome was satisfactory with progressive filling of the acetabular defect but also with development of a subluxating coxa valga which required varus osteotomy of the femur. This case appears to illustrate a particular form of subacute osteomyelitis which is not described in earlier classifications.

Unusual upper cervical fracture in a 1-year-old girl.

Injuries to the child's cervical spine are rare and, unlike adults, most common from the occiput to C3. Most odontoid fractures in children occur through the basilar synchondrosis and only the dens is displaced anteriorly. The authors report the clinical and radiologic evaluation of a child who sustained an unusual cervical injury during a motor vehicle accident. The lesion consisted of an epiphyseal fracture-separation between the body and the neural arches of C2. There was also an associated spinal cord lesion.

Septic arthritis of the hip due to Fusobacterium nucleatum.

Anaerobic bacteria are uncommon pathogens in septic arthritis. We report a case of pyarthrosis of the right hip caused by Fusobacterium nucleatum, following a transient synovitis in an otherwise healthy boy. There are only a few cases involving this species described in the literature. This report illustrates the difficulty of isolating this unusual organism and emphasises the usefulness of the Bactec blood culture bottles for the recovery of anaerobic bacteria.

Surface of localized pleural plaques quantitated by computed tomography scanning: no relation with cumulative asbestos exposure and no effect on lung function.

To evaluate if there is a relation between the size of asbestos plaques and the level of past exposure and pulmonary function, we measured the surface of localized pleural plaques found on high-resolution (HR) CT scan, using a computerized video display unit-imaging system, in 73 workers (mean age, 43.5 yr) who had worked from 23 to 27 yr in an asbestos-cement factory. Their estimated cumulative exposure to asbestos ranged from 16.4 to 98.7 fiber-years/ ml (mean, 26.3 fiber-years/ml). Lung function measurements included lung volumes, maximal expiratory flows, and diffusing capacity. A control group of 21 workers was examined by the same procedures. Plaques were detected by CT in 51 (70%) asbestos-exposed subjects and in none of the control subjects. The average calculated plaque surface was 47.9 +/- 61.7 cm2 (median, 22.1 cm2; range, 0 to 278.4 cm2). There was no relation between plaque surface and cumulative asbestos exposure (p = 0.24). In the 51 subjects with pleural plaques, the surface of the pleural lesions was not related to cumulative asbestos exposure, or to smoking history or time since first exposure. Neither the presence nor the extent of the plaques was correlated with lung function parameters.

[The syndrome of external ligament sprain in the horse]. / Le syndrome de l'entorse externe de la cheville.

The treatment of acute complete (grade III) tears of the lateral ligaments of the ankle has generated much controversy in the medical literature. Functional treatment has become the standard treatment as it has been shown that there is no significant difference in long term results whatever the treatment (operative repair and cast, cast alone, or early controlled mobilization). Functional treatment includes only a short period of protection by tape bandage or brace and allows early weight-bearing. Major trauma with avulsion of bone and severe ligamentous damage on both medial and lateral sides of the ankle is however an indication for surgical treatment in the acute phase. Secondary operative reconstruction can be performed in case of persistent instability and laxity of the ankle. Secondary anatomic repair as proposed by Brodström, Duquennoy et al. and Karlsson et al. has a high rate of success and avoids the potential morbidity of harvesting partially or totally the peroneus brevis or other tendon grafts. Evaluation of the injured ankle has improved and in selected patients ultrasonography, arthrography, magnetic resonance imaging or bone scintigraphy may be useful for further evaluation of the injury. The frequency of associated injuries has probably been underestimated. Although ankle sprain is often thought of as an injury involving only the lateral ankle ligaments, there are varied and multiple components to the common sprained ankle. This condition would perhaps more appropriately be designated as the sprained ankle syndrome.

Dual-detector spiral CT arthrography of the knee: accuracy for detection of meniscal abnormalities and unstable meniscal tears.

PURPOSE: To determine the sensitivity and specificity of dual-detector spiral computed tomographic (CT) arthrography of the knee in the detection of meniscal abnormalities and unstable meniscal tears. MATERIALS AND METHODS: The meniscal changes in 50 consecutive patients who underwent dual-detector spiral CT of the knee after intraarticular injection of iodinated contrast material (0.55-mm effective section thickness, 0.75 pitch value, 0.3-mm increment reconstruction, 0.43-mm in-plane resolution, 0.3-mm longitudinal resolution) were determined by two observers and were compared with arthroscopic findings. The sensitivity and specificity of CT arthrography for the detection of meniscal abnormalities and unstable meniscal tears and the kappa statistics for assessing interobserver reproducibility were determined. RESULTS: The sensitivity and specificity for the detection of meniscal abnormalities were 98% and 94%, respectively. The sensitivity and specificity for the detection of unstable meniscal tears were 97% and 90%, respectively. Interobserver agreement was excellent for the detection of meniscal abnormalities (kappa = 0.899) and of unstable meniscal tears (kappa = 0.885). CONCLUSION: Dual-detector spiral CT arthrography of the knee is an accurate and reproducible method for detecting meniscal abnormalities and unstable meniscal tears.

Growth disturbance of the ilium after splitting the iliac apophysis and iliac crest bone harvesting in children: a retrospective study at the end of growth following unilateral Salter innominate osteotomy in 21 children.

The morphology of the iliac bone was assessed at the end of growth on AP x-rays of the pelvis in 21 children who had previously undergone unilateral pelvic osteotomy. The nonoperated side was used as a reference. There were 13 girls and 8 boys. Age at operation varied from 12 months to 12 years with a mean of 3 years and 10 months. The patients were distributed in 2 groups depending on their age at operation: before age 5 (group A, 16 cases) or after age 5 (group B, 5 cases). The mean age at follow-up was 15 years and 2 months (range 11-19 years). The end of pelvic growth was established by Risser stage IV. Distinct hypoplasia of the ilium due to premature growth arrest was observed in 16 cases: 12 in group A and 4 in group B. Other changes in the morphology of the ilium were noted, e.a. increased height of the ilium which was noted in 12 cases. The cosmetic prejudice was however minor, as compared with the radiological changes. In the authors' opinion, the alar hypoplasia was related to growth disturbances due to repeated splitting of the iliac apophysis. To prevent this complication the authors recommend avoiding the use of an electrocautery to incise the iliac apophysis and cutting the Kirschner wires so that their proximal ends lie within the subcutaneous fat, in order to avoid repeated splitting of the apophysis at the time of hardware removal.

Reflex sympathetic dystrophy in children: review of a clinical series and description of the particularities in children.

Few series on reflex sympathetic dystrophy syndrome (RSDS) have included children. The present series reviewed 10 affected children. The group consisted of 9 girls and one boy with an average age at onset of 11 years (5 years to 16 years). The diagnosis was based on the clinical findings of pain, dysesthesia and autonomic system dysfunction. All patients underwent x rays and bone scans. Their results showed great variation. Minor trauma was the most common trigger factor. The lower extremities were more often involved. The treatment consisted of pain relief and progressive mobilization. Less conventional treatments in children, such as calcitonin and bisphosphonate were also used. The severity and duration of the disease varied greatly among these children. Moderate pain and sympathetic dysfunction persisted often up to two years after onset. Reflex sympathetic dystrophy is more common in children than previously thought. There are differences with the adult form in presentation and clinical course: the diagnosis is often delayed, the lower extremities are more often involved, girls are affected more often and idiopathic forms are frequent. Significant emotional dysfunction is found in a majority of patients and they are best treated as inpatients by a multidisciplinary team.

Long-term functional results of wrist arthrodesis in rheumatoid arthritis.

The purpose of this study was to evaluate the long-term effectiveness of wrist fusion on the relief of pain and also the functional capacities of the upper limbs in patients with rheumatoid arthritis (RA). Eighteen patients were assessed at a mean of 7 years after wrist arthrodesis and a mean of 17 years after the onset of RA. Radiological measurements, pain assessment and impairment rating of the upper limbs were made of the fused and non-fused sides. The average position of arthrodesis was 8 degrees of extension and 9 degrees of ulnar deviation. All patients were pleased with the procedure and had satisfactory pain relief. Impairment ratings did not detect any significant difference in the sensory and motor function of the hand when the fused and non-fused groups were compared. We conclude that in patients with rheumatoid arthritis, wrist arthrodesis is a reliable procedure that provides predictable pain relief and a high degree of satisfaction without additional functional loss in the upper limb.

[Evolution of post-fracture bone deformities in an infant with hepatic osteodystrophy on Alagille syndrome]. / Evolution des déviations osseuses post fracturaires chez une enfant atteinte d'ostéodystrophie hépatique sur syndrome d'Alagille.

INTRODUCTION: This case report describes the evolution of postfractural axial bone deviations that occurred in a child with hepatic osteodystrophy due to an Alagille Syndrome. Postfractural bone deformities in children trend to spontaneous correction if there is a remaining growth potential. In case of severe hepatic osteodystrophy correlated by liver transplantation, we have observed spontaneous correction of a posttraumatic valgus deformity of the leg, as well as worsening of a diaphyseal femoral bowing. We tried to explain this apparently paradoxal evolution. CASE REPORT: Andrea St. is born in 1984 with multiple malformations corresponding to Alagille Syndrome: ductulus paucity, pulmonary arterial hypoplasia, posterior embryotoxin and "butterfly vertebrae". She has developed a cholostatic icterial and a portal hypertension due to a hepatic cirrhosis which needed an hepatic transplantation at the age of 8 years. Before her transplantation, Andrea St developed postfractural axial bone deviations. At the age of 7 years, she had a tibia valgum of 20 degrees and a femoral bowing of 50 degrees. With the normalization of the metabolism due to the hepatic transplantation, the osteopenia as well the tibia valgum of 20 degrees has been corrected spontaneously up to 8 degrees and there was a worsening of the femoral bowing up to 50 degrees. DISCUSSION: The physiopathology of the hepatic osteodystrophy is not yet perfectly known. Treatment with Vitamin D and Calcium doesn't seem to prevent hepatic osteodystrophy. Salter reported that postfractural bone angulation in children will spontaneously correct itself if on one hand it is not far from the growth cartilage and on the other hand if it is in the same mobility plane than the adjacent articulation. Postfractural diaphyseal bone deformities tend to correct spontaneously if the angulation is less than 20 to 30 degrees. Concerning fractures of the proximal tibia in children, they develop frequently a progressive tibia valgum deformity, even if the fracture was not primary displaced. However we know that all proximal tibial fractures in children don't give residual valgus deformities, and that several postfractural tibia valgum correct spontaneously. This has been explained by a temporary growth acceleration of the medial part of the proximal tibial growth plate. In this case, the femoral bowing worsened. This is explained by the mediodiaphyseal location of the deformation, and the importance of the bone deviation much bigger than the threshold of 20 to 30 degrees that may not be overtaken to hope a spontaneous correction. The evolution of the proximal metaphyseal tibial fracture consisted firstly in a progressive valgus deformation that resolved spontaneously after hepatic transplantation.

Simple bone cysts treated with aspiration and a single bone marrow injection. A preliminary report.

The results of a single percutaneous aspiration and injection of marrow into active, simple bone cysts are reported in 8 cases. Slow regression of the cyst was consistently observed except in one lesion in the distal tibia. All the patients have been free of symptoms after this treatment after a mean follow up of 31 months. The evolution of the cysts was monitored by a cyst index, cyst diameter measurements and computer assisted densitometric image analysis of serial radiographs.

Injury to the brachial plexus by a fragment of bone after fracture of the clavicle.

Clavicular fractures are occasionally responsible for lesions of the brachial plexus. The symptoms are usually delayed and due to compression by hypertrophic callus, nonunion or a subclavian pseudoaneurysm. We describe a patient in whom a displaced bone fragment was pressing on the retroclavicular part of the brachial plexus, leading to early symptoms of a lesion of the posterior cord. Internal fixation of the clavicle and external neurolysis of the brachial plexus gave an almost full recovery.

[Contribution of electromyographic analysis of the walking habits of children with spastic foot in cerebral palsy: a preliminary study]. / L'apport de l'analyse électromyographique de la marche dans l'étude du pied spastique de l'infirme moteur d'origine cérébrale: étude préliminaire.

PURPOSE OF THE STUDY: This preliminary study describes the methodology and the results of gait analysis in cases of equinus and equino-varus deformity of the foot in cerebral palsy children. The ultimate goal was to establish an aid to decision in spastic foot surgical management. MATERIAL: A prospective series of 12 walking children (16 feet) with cerebral palsy has been evaluated prior to surgical correction of equinus or equino-varus deformity of the foot. The mean age was 8 years (range 4 to 11 years of age). METHOD: The pattern of muscle activity during gait cycle has been recorded by surface electrodes for the tibialis anterior, the triceps and the peroneae and by implanted electrodes for the tibialis posterior. Foot switches have been used to differentiate swing and stance gait phases. The results were compared with these of a series of normal children previously published. RESULTS: In four cases, the dynamic equinus was due to an extended or continuous contraction of the triceps surae. The varus deformity appeared to originate from two muscles: the tibialis posterior in 9 cases and the tibialis anterior in 1 case. Both muscles were responsible for the deformity in 2 cases. Two muscular activation patterns were observed in the tibialis posterior: inverted (2 feet) or permanent (9 feet). From the main muscle which was responsible for deformity, we have determined the surgical technique which was most appropriate to restore the muscular balance. DISCUSSION: Our observations confirm Perry's hypothesis, namely that selective and phasic control during the walking cycle does not occur for patients suffering from cerebral palsy. Different surgical procedures were chosen according to the literature on this subject. In the treatment of equinus deformity, lengthening of the Achilles tendon is a satisfactory technique for hemiplegic patients. But we prefer gastrocnemius recession described by Vulpius in spastic diplegia in order to avoid over-lengthening or calcanal gait. If it can be shown that posterior tibial muscle overactivity is the cause of equinovarus, we perform a posterior tibial tendon lengthening, as proposed by Ruda and Frost, or a split posterior tibial tendon transfer as developed by Green. If the posterior tibial muscle is active only during the swing phase, we accomplish a split posterior tibial tendon transfer through the interosseus membrane as advocated by Saji. If the anterior tibial muscle is continuously active, a split anterior tibial tendon transfer to the cuboid described by Hoffer is performed. If the activity is continuous in both the tibial posterior and the tibial anterior muscles, we add a posterior tibial myotendinous lengthening to the split anterior tibial tendon transfer. CONCLUSION: Since 1992, we have developed in our institution a gait analysis laboratory in order to bring objective data in the process of decision making for tendon transfer surgery. With 4 years experience, this objective support now seems to us compulsory in decision of type of transfer. The goal of this preliminary study was to explain how we use the data and match these to our experience and literature.

A simple, non-invasive method for the measurement of reserpine-induced tremor in rats.

A new, non-invasive method for measuring reserpine-induced tremor in rodents is described here. The test procedure is based on the piezo-electric principle and was evaluated using the tremorogenic compound reserpine and the stereotypies-inducing drug apomorphine. Whereas for reserpine an orderly and dose-related increase in activity was observed, no such effect was detected with apomorphine. In order to further evaluate the test procedure, studies on the antagonism of reserpine-induced tremor were also performed. Results from these studies indicated that the DA-agonist lisuride, but not the S2-antagonist ritanserin, were able to antagonize the reserpine-induced tremor in a dose-related manner.

[Complications of supracondylar fractures of the humerus in children]. / Les complications des fractures supracondyliennes de l'humérus chez l'enfant.

The supracondylar fracture of the humerus is the commonest type of elbow fracture in children. The peak incidence for this injury is between 5 and 10 years of age. The complications of these displaced fractures remain challenging problems. The early complications are mostly the neuro-vascular injuries. The difficulty in maintaining the reduction and ultimately the cubitus varus is the most frequent long-term complication with an incidence ranging from 3 to 57%. Adequate reduction and pinning has dramatically decreased this incidence. This paper describes these complications and their treatments.

[Involvement of the shoulder in rheumatoid arthritis]. / L'atteinte de l'épaule au cours de la polyarthrite rhumatoïde.

The course of rheumatoid arthritis (R.A.) in the shoulder is evaluated in 100 patients in a retrospective study and in 73 patients in a prospective study. The involvement of the shoulder may occur at an early stage of the disease. However, usually it causes a significant handicap at a later stage. The retrospective study shows that 62% of the patients hospitalized between 1976 and 1992 for R.A. complained of pain, reduction in range of motion and functional disability of one or both shoulders. However, these historic cases cannot be used for a radiological study because the shoulders have been radiographed in 17% of cases only, probably because of the poor possibilities of surgical therapies available at this time. The survey of 72 patients received at the out- patient clinic between september 1992 and december 1993 who had a radiograph of the shoulder is the basis for the description of the progress of the disease. The erosions appear at the border of the cartilage where the synovium is attached and refers mainly to the cephalic articular cartilage. Narrowing of the subacromial space is often present with early appearance of subluxation in the cranial direction. The destruction often prevails in the area of humeral head but cases with predominant global joint space narrowing or with destruction of glenoid labrum and fossa exist as well. Secondary osteoarthritis was often observed. The involvement of the shoulders is not always symmetric. Unilateral involvement has been observed. The different evolutive processes will be illustrated and their frequency evaluated. The forms with predominant cephalic destruction constitute the best indications for total shoulder arthroplasty.

Functional dyspepsia versus other functional gastrointestinal disorders: a practical approach in Belgian general practices.

This paper identifies the symptom profile associated with the four main diagnoses of functional digestive disorders (dyspepsia, gastro-oesophageal reflux disease (GORD), gastritis, and constipation) made by general practitioners in Belgium. Results are also presented from a multicentre study in which the effects of cisapride, administered as an oral tablet or suspension, were evaluated in patients with these functional digestive disorders. Analysis of symptom patterns revealed that early satiety and postprandial abdominal bloating were the most prominent symptoms, followed by eructation (belching), heartburn, regurgitation, postprandial epigastric burning or discomfort, and nausea. These symptoms occurred in all diagnostic groups. However, different symptom patterns were associated with each of the disorders; for example, heartburn and regurgitation were the core symptoms in patients diagnosed as having GORD, early satiety and abdominal bloating were characteristic of patients diagnosed with dyspepsia, and fasting or postprandial pain were characteristic of patients given the diagnosis of gastritis. Therefore, it appears that these diagnoses used by general practitioners in Belgium closely correspond to reflux-like, dysmotility-like and ulcer-like dyspepsia, as defined by an international working party. Cisapride improved the core symptoms in about 80% of patients with GORD or dyspepsia, relieved all epigastric symptoms in about 80% of patients with gastritis, and significantly decreased the use of laxatives and increased stool frequency in constipated patients. Cisapride was well tolerated and thus appears to be a useful option in the treatment of functional digestive disorders in a general practice setting.