Frederic Shapiro

Cell origin and differentiation in the repair of full-thickness defects of articular cartilage.

The origin and differentiation of cells in the repair of three-millimeter-diameter, cylindrical, full-thickness drilled defects of articular cartilage were studied histologically in New Zealand White rabbits. The animals were allowed to move freely after the operation. Three hundred and sixty-four individual defects from 122 animals were examined as long as forty-eight weeks postoperatively. In the first few days, fibrinous arcades were established across the defect, from surface edge to surface edge, and this served to orient mesenchymal cell ingrowth along the long axes. The first evidence of synthesis of a cartilage extracellular matrix, as defined by safranin-O staining, appeared at ten days. At two weeks, cartilage was present immediately beneath the surface of collagenous tissue that was rich in flattened fibrocartilaginous cells in virtually all specimens. At three weeks, the sites of almost all of the defects had a well demarcated layer of cartilage containing chondrocytes. An essentially complete repopulation of the defects occurred at six, eight, ten, and twelve weeks, with progressive differentiation of cells to chondroblasts, chondrocytes, and osteoblasts and synthesis of cartilage and bone matrices in their appropriate locations. At twenty-four weeks, both the tidemark and the compact lamellar subchondral bone plate had been re-established. The cancellous woven bone that had formed initially in the depths of the defect was replaced by lamellar, coarse cancellous bone. Autoradiography after labeling with 3H-thymidine and 3H-cytidine demonstrated that chondrocytes from the residual adjacent articular cartilage did not participate in the repopulation of the defect. The repair was mediated wholly by the proliferation and differentiation of mesenchymal cells of the marrow. Intra-articular injections of 3H-thymidine seven days after the operation clearly labeled this mesenchymal cell pool. The label, initially taken up by undifferentiated mesenchymal cells, progressively appeared in fibroblasts, osteoblasts, articular chondroblasts, and chondrocytes, indicating their origin from the primitive mesenchymal cells of the marrow. Early traces of degeneration of the cartilage matrix were seen in many defects at twelve to twenty weeks, with the prevalence and intensity of the degeneration increasing at twenty-four, thirty-six, and forty-eight weeks. Polarized light microscopy demonstrated failure of the newly synthesized repair matrix to become adherent to, and integrated with, the cartilage immediately adjacent to the drill-hole, even when light microscopy had shown apparent continuity of the tissue. In many instances, a clear gap was seen between repair and residual cartilage.(ABSTRACT TRUNCATED AT 400 WORDS)

Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and pharmacological and psychosocial management

Duchenne muscular dystrophy (DMD) is a severe, progressive disease that affects 1 in 3600-6000 live male births. Although guidelines are available for various aspects of DMD, comprehensive clinical care recommendations do not exist. The US Centers for Disease Control and Prevention selected 84 clinicians to develop care recommendations using the RAND Corporation-University of California Los Angeles Appropriateness Method. The DMD Care Considerations Working Group evaluated assessments and interventions used in the management of diagnostics, gastroenterology and nutrition, rehabilitation, and neuromuscular, psychosocial, cardiovascular, respiratory, orthopaedic, and surgical aspects of DMD. These recommendations, presented in two parts, are intended for the wide range of practitioners who care for individuals with DMD. They provide a framework for recognising the multisystem primary manifestations and secondary complications of DMD and for providing coordinated multidisciplinary care. In part 1 of this Review, we describe the methods used to generate the recommendations, and the overall perspective on care, pharmacological treatment, and psychosocial management.

Diagnosis and management of Duchenne muscular dystrophy, part 2: implementation of multidisciplinary care

Optimum management of Duchenne muscular dystrophy (DMD) requires a multidisciplinary approach that focuses on anticipatory and preventive measures as well as active interventions to address the primary and secondary aspects of the disorder. Implementing comprehensive management strategies can favourably alter the natural history of the disease and improve function, quality of life, and longevity. Standardised care can also facilitate planning for multicentre trials and help with the identification of areas in which care can be improved. Here, we present a comprehensive set of DMD care recommendations for management of rehabilitation, orthopaedic, respiratory, cardiovascular, gastroenterology/nutrition, and pain issues, as well as general surgical and emergency-room precautions. Together with part 1 of this Review, which focuses on diagnosis, pharmacological treatment, and psychosocial care, these recommendations allow diagnosis and management to occur in a coordinated multidisciplinary fashion.

Tranexamic Acid Reduces Intraoperative Blood Loss in Pediatric Patients Undergoing Scoliosis Surgery

Background: Excessive bleeding often occurs during pediatric scoliosis surgery and is attributed to numerous factors, including accelerated fibrinolysis. The authors hypothesized that administration of tranexamic acid would reduce bleeding and transfusion requirements during scoliosis surgery. Methods: Forty-four patients scheduled to undergo elective spinal fusion were randomly assigned to receive either 100 mg/kg tranexamic acid before incision followed by an infusion of 10 mg · kg−1 · h−1 during surgery (tranexamic acid group) or 0.9% saline (placebo group). General anesthesia was administered according to a standard protocol. Blood loss, transfusion requirements, coagulation parameters, and complications were assessed. Results: In the tranexamic acid group, blood loss was reduced by 41% compared with placebo (1,230 ± 535 vs. 2,085 ± 1,188 ml; P < 0.01). The amount of blood transfused did not differ between groups (615 ± 460 vs. 940 ± 718 ml; P = 0.08). Administration of tranexamic acid was a multivariate predictor of blood loss, as was American Society of Anesthesiologists physical status and preoperative platelet count. No apparent adverse drug effects occurred in any patient. Conclusion: Intraoperative administration of tranexamic acid significantly reduces blood loss during spinal surgery in children with scoliosis.

Fractures of the femoral shaft in children. The overgrowth phenomenon.

Femoral overgrowth following femoral shaft fracture in children less then 13 years old has been documented by orthoroentgenogram in 74 patients from the time of healing 3 months following fracture until skeletal maturity. The femoral overgrowth averaged 0.92 centimeters (range 0.4-2.7) and was found to be independent of age, level of fracture, or position of fracture at the time of healing. The overgrowth was a universal phenomenon. Ipsilateral tibial overgrowth averaging 0.29 centimeters (0.1-0.5) occurred in 82 per cent of the patients. In the first 18 months following fracture 78 per cent of the overgrowth occurred. There was a time limit to the overgrowth phenomenon in 91 per cent of all patients following which the discrepancy persisted without change. By 18 months following fracture, however, only 12 per cent of the patients had completed the overgrowth and by 3 years and 6 months following fracture 85 per cent had completed their overgrowth. In 9 per cent of the patients overgrowth continued throughout the remaining growth period although at a slower rate than in the first 18 months following fracture.

Structural stages in the development of the long bones and epiphyses: a study in the New Zealand white rabbit.

Background: Histologic delineation of the events involved in the development of long bones and the developmental age at which these events occur is needed to elucidate the genetic and molecular mechanisms associated with these events. This report describes the sequence of histologic events involved in the formation of long bones and their epiphyses in the New Zealand White rabbit. Methods: Prenatal studies were performed on twelve, fourteen, fifteen, sixteen, eighteen, twenty-one, twenty-four, and twenty-seven-day-old rabbit embryos, and postnatal studies were performed on newborn rabbits and on three-to-four-day-old; one, two, four, and six-week-old; and two, three, four, six, and eight-month-old rabbits. Histologic specimens from embryos were embedded in plastic and stained with toluidine blue or safranin O-fast green, and specimens from postnatal rabbits were embedded in paraffin and stained with hematoxylin and eosin or safranin O-fast green. Results: Studies of twelve-day-old embryos demonstrated upper and lower limb buds filled with undifferentiated mesenchymal cells, and studies of fourteen-day-old embryos showed mesenchymal condensation and beginning cartilage formation outlining major long bones. Long-bone and epiphyseal development progressed through sixteen structural stages, and the developmental age at which these stages occurred was determined. These stages included limb-bud formation with uniform distribution of mesenchymal cells and formation of an apical ectodermal ridge (stage 1); mesenchymal condensation (stage 2); cartilage differentiation (stage 3); formation of a primary center of ossification (stage 4a); epiphyseal cartilage vascularization with formation of cartilage canals (stage 7); vascular invasion of the developing secondary ossification center (stage 9); bone formation and marrow cavitation in the secondary ossification center with formation of hematopoietic marrow (stage 10); fullest relative extent of secondary-ossification-center development in epiphyseal cartilage (stage 14); thinning of the physis (stage 15); and resorption of the physis with establishment of continuity between epiphyseal and metaphyseal circulations (stage 16). Clinical Relevance: The detailed classification system presented here will allow for correlations between genetic and molecular mechanisms and histologic events in normal and abnormal development of long bones and their epiphyses. Many of the nonosseous structures formed during long-bone and epiphyseal development in the fetus, infant, and child are amenable to assessment with sonography and magnetic resonance imaging. An understanding of the histopathological features of developmental abnormalities of the long bones and their epiphyses revealed with newer imaging techniques should greatly improve management by allowing earlier diagnosis.

Cortical bone repair. The relationship of the lacunar-canalicular system and intercellular gap junctions to the repair process.

Repair of cortical bone was studied in 2.4-millimeter-diameter mid-diaphyseal femoral and tibial defects in young New Zealand White rabbits using light microscopy, transmission electron microscopy, and histomorphometry. The initial source of repair tissue is the marrow. Vessels grow into the defect, accompanied by undifferentiated mesenchymal cells. Woven bone is synthesized initially at the periphery of the defect on pre-existing cortex. Differentiating mesenchymal osteoblasts surround themselves with osteoid in a woven conformation. Once a scaffold has formed, surface osteoblasts align themselves in a regular array on the woven matrix surface and synthesize osteoid in a lamellar conformation. The long axes of the repair vessels, lamellae, and osteocyte lacunae are perpendicular to the long axis of the bone. Polarized-light microscopy showed maintenance of this pattern at six, eight, and twelve weeks, even when the defect was filled with lamellar bone. Remodeling is performed slowly by osteoclast cutting cones over a period of several months. The lacunar-canalicular system is clearly demonstrated in plastic-embedded, toluidine blue-stained sections. A canaliculus passes into or away from a lacuna every 1.9 micrometers over the entire osteocyte perimeter. Undifferentiated mesenchymal cells have no processes, as seen by transmission electron microscopy, but soon sprout a florid array of processes as differentiation to early mesenchymal osteoblasts proceeds. Osteoblast and osteocyte cell processes are packed with intermediate filaments that are continuous with those in the cell bodies. Intercellular gap junctions are seen between surface osteoblasts, between osteoblasts and underlying osteocytes, and between osteocyte cell processes in the canaliculi.

Tranexamic acid diminishes intraoperative blood loss and transfusion in spinal fusions for duchenne muscular dystrophy scoliosis.

Study Design. Retrospective review of intraoperative blood loss and blood replacement. Objective. We compared intraoperative blood loss and blood replacement during spinal fusion surgery for scoliosis in Duchenne muscular dystrophy (DMD) performed with and without the synthetic antifibrinolytic agent tranexamic acid (TXA). Summary of Background Data. High levels of intraoperative blood loss are widely documented in DMD patients undergoing posterior spinal fusion for scoliosis. The effect of the antifibrinolytic agent tranexamic acid on decreasing the blood loss has not been studied in a large group of DMD patients. Methods. All 56 DMD patients underwent posterior spinal fusion with the same technique using 2 rods and multiple sublaminar wires. TXA was not used in 36 patients and was used in 20. In the respective groups, the age at surgery (14 vs. 13.9 years), the preoperative deformity (45° vs. 51°), the mean number of levels fused (14.3 vs. 14.7), and the mean surgical times (446 minutes vs. 459 minutes) were similar. TXA dose was 100 mg/kg in solution over 15 minutes before incision followed by an infusion of 10 mg/kg per hour during surgery. Standardized measurements of intraoperative blood loss were used and calculated to compare total amount of blood loss in milliliters per patient and blood loss as a percentage in relation to estimated blood volume [estimated blood loss (EBL)/estimated blood volume (EBV) × 100]. The EBV was calculated to be 70 mL/kg (body weight). Results. Mean blood loss with TXA was 1944 ± 789 mL (range, 760–4000 mL) and without TXA was 3382 ± 1795 mL (range, 600–9580 mL) (P < 0.001). Blood loss with TXA decreased by 42% compared with those not treated with TXA. Accounting for patient weight and estimated blood volume, mean % blood loss with and without TXA was 47% ± 28% versus 112% ± 67% (P < 0.001). This physiologic indicator shows that blood loss with TXA decreased by 58% compared with those patients not treated with TXA. TXA was also found to reduce blood loss after accounting for surgical time. No hypercoagulation or other complications from TXA therapy were obs-erved. The reduced blood loss in TXA-treated patients translated into decreased blood transfusions. Transfusion of homologous whole blood and packed red blood cells in the TXA group was decreased by 46% compared with the no TXA group (mean levels, 512 ± 470 mL vs. 955 ± 718 mL), and transfusion of autologous cell saver blood was decreased by 42% in the TXA group (mean levels, 419 ± 235 mL vs. 728 ± 416 mL). Conclusion. TXA significantly reduces both intraoperative blood loss and the need for homologous transfusion of whole blood and packed red blood cells in DMD patients undergoing posterior spinal fusion for scoliosis.

Association of Duchenne Muscular Dystrophy With Autism Spectrum Disorder

We hypothesize that Duchenne muscular dystrophy and autism spectrum disorder/pervasive developmental disorder co-occur with a greater than random frequency. In this study, we set out to reject the hypothesis that Duchenne muscular dystrophy and autism spectrum disorder/pervasive developmental disorder co-occur no more often than expected by chance. Two index cases and six additional boys with concomitant Duchenne muscular dystrophy and autism spectrum disorder were identified in a muscular dystrophy clinic that approximates the total number of Duchenne muscular dystrophy boys (158) in the state of Massachusetts. The rate of prevalence (6 of 158) was compared with the prevalence rate of autism spectrum disorder in boys in the general population (1.6 in 1000). We rejected the hypothesis that Duchenne muscular dystrophy and autism spectrum disorder co-occurrence was likely to be explained by chance (P = .006). We identify a previously unrecognized association of Duchenne muscular dystrophy with autism spectrum disorder. Further work might elucidate the level of association between these two conditions, either at the genetic or at the protein level, and might clarify, at least partially, the neurobiologic mechanisms associated with autism spectrum disorder. (J Child Neurol 2005;20:790—795).

Blood loss in pediatric spine surgery

This article reviews the extent of blood loss in spine surgery for scoliosis corrections in the pediatric age group. An extensive literature review presents blood loss values in surgery for adolescent idiopathic scoliosis, cerebral palsy, Duchenne muscular dystrophy, spinal muscular atrophy, and myelomeningocoele. The underlying disorder plays a major role in determining the extent of blood loss. Blood loss is considerably higher in those patients with a neuromuscular scoliosis compared with adolescent idiopathic scoliosis. Within the neuromuscular group those with Duchenne muscular dystrophy demonstrate the highest mean levels of blood loss. Blood loss is also shown to be progressively greater with increasing numbers of vertebral levels incorporated into the fusion, with posterior fusions compared to anterior fusions, and in those patients having both anterior and posterior fusions.