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Several models of scoliosis were developed in the past 10 years. In most of them, deformations are induced in old animals and required long time observation period and a chest wall ligation ± resection. The purpose of the study was to create a scoliosis model with a size similar to an early onset scoliosis and an important growth potential without chest wall injuring. An original offset implant was fixed posteriorly and connected with a cable in seven (6 + 1 control) one-month-old Landrace pigs. The mean initial spinal length (T1-S1) was 25 cm and the mean weight was 9 kg. After 2 months observation, spinal deformities were assessed with a three dimension stereographic analysis. In four animals, the cable was sectioned and the deformities followed-up for next 2 months. No post-operative complication was observed. Mean weight growth was 10 kg/month and mean spine lengthening (T1-S1) was 7 cm/month. In 2 months, we obtained structural scoliotic curves with vertebral and disk wedging which were maximal at the apex of the curve. Mean frontal and sagittal Cobb angles was 45°. Chest wall associated deformities were similar to those observed in scoliotic deformities and were correlated to spinal deformities (p = 0.03). The cable section resulted in a partial curve regression influenced by disk elasticity and could probably be influenced by gravity loads (Decrease of the Cobb angle of 30% in the sagittal plane and 45% in the frontal plane). According to the results, the model creates a structural scoliosis and chest wall deformity that is similar to an early onset scoliosis. The spinal deformities were obtained quickly, and were consistent between animals in term of amount and characteristic. [ABSTRACT FROM AUTHOR]

We reviewed 5 cases of type I epiphyseal fracture with dislocation of the femoral head from the acetabulum in adolescent patients. All children had an open reduction and screw fixation. In all cases, the femoral head developed avascular necrosis. The clinical result after a mean of 3-9 years' follow-up was good according to the Merle d'Aubigné-Postel scale. Despite necrosis, 2 heads developed spherically after treatment: one which had a primary physeal resection and fixation, the other after an autogenous bone graft in the screw track following removal of the screw. [ABSTRACT FROM AUTHOR]

Introduction: The choice of surgical technique for high-grade spondylolisthesis (HGS) associated with lumbosacral kyphosis remains controversial. Are non-instrumented techniques still relevant, what with the multiplicity and modernity of patient-specific instrumentation?, Hypothesis: Our hypothesis was that a non-instrumented circumferential arthrodesis performed after a period of gradual reduction of HGS, associated with lumbosacral kyphosis, provided satisfactory long-term functional and radiographic results in children and adolescents while minimizing the risk of complications., Materials and Methods: Thirty-one L5-S1 HGS associated with a lumbosacral kyphosis operated by non-instrumented circumferential arthrodesis after a period of traction and suspension were included in our study. The first stage of this technique consisted of a gradual reduction using traction followed by immobilization in the corrected position. The second stage involved a posterior, followed by an anterior, surgical procedure and a spica cast immobilization for 4 months. The mean age at surgery was 13.9±2.3 years (6-18) and the mean follow-up was 10.3±4.5 years (2.1-17.8)., Results: The overall complication rate was 26% (n=8/31): 13% neurologic complications, 10% bone fusion defects and 3% skin complications. The reoperation rate was 13% (n=4/31). The mean ODI (/50) was 3±4.6 (0-22) and the SRS-30 126.7±15 (72-143). The Taillard index decreased by 25% (p<.001) and remained stable throughout the follow-up period (p=.65). The lumbosacral angle was corrected by 13.5% (p=.03) and the correction was maintained throughout the follow-up period (p=.71). At the last follow-up, the lumbosacral angle was significantly correlated with a low ODI score and a high SRS-30 score (p<.05)., Conclusion: Even though this technique achieved a smaller reduction of the lumbosacral angle, it reduced by at least a factor of three the incidence of neurologic complications and resulted in satisfactory functional outcomes when compared to instrumented and intraoperative correction series., Level of Evidence: IV., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Background: Spinal osteochondroma (or exostosis) is a rare benign tumour whose clinical manifestations are delayed due to their slow growth and location. Few studies have addressed the characteristics and the diagnostic and therapeutic peculiarities of spinal osteochondroma in children. The objective of this multicentre observational study was to assess the outcomes of a cohort of children after surgery for spinal osteochondroma., Hypothesis: Surgical excision of spinal osteochondroma in children is not followed by complications or recurrences., Material and Methods: We included consecutive children who had surgery between 2010 and 2018 at any of eight participating centres to remove spinal osteochondromas. The cause, clinical manifestations, and location of the lesions were collected. The surgical outcomes were evaluated after at least 2 years' follow-up., Results: We identified 22 patients who had surgery to remove 26 spinal osteochondromas at a mean age of 12.8±2.6 years. Among them, 7 had a solitary osteochondroma (SO group) and 15 had hereditary multiple osteochondromas (HMO group). At diagnosis, 72% of patients had clinical signs (spinal pain, n=4; one or more lumps, n=5; and neurological manifestations, n=3). In the HMO group, the diagnosis was made during routine MRI screening for tumours involving the spinal canal. Most osteochondromas involved the cervical spine (n=13), with no difference between the two groups (p=0.9). The lamina was the most common location but 54% of the tumours were growing within the canal (92% in the HMO group). After a mean follow-up of 5.2±4.4 years, no patients had experienced any recurrences or complications related to the disease or treatment., Discussion: Surgical excision of spinal osteochondromas in children is effective, with no medium-term recurrences. Our results also confirm the low peri-operative morbidity, even when the canal is involved, and the absence of any effect at last follow-up on spinal alignment. All patients with neurological manifestations at diagnosis made a full recovery., Level of Evidence: IV, retrospective observational cohort study., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Introduction: Neurogenic thoracic outlet syndromes (TOS) are dominated by the nonspecific forms. This study focuses only on the rarer true forms related to proximal nerve compression in the thoracic outlet, with the presence of motor (atrophy of the hand's intrinsic muscles) and/or sensory (hypoesthesia in the territory of the medial antebrachial cutaneous nerve) deficits. The objectives of this study were to define the clinical characteristics, anatomical causes and surgical results of this condition., Patients and Methods: Single-center retrospective study of 53 consecutive cases in 50 patients with an objective clinical deficit confirmed by nerve conduction studies. The population consisted of 47 adults and 3 children, 9 males and 41 females, with a mean age of 39 years (9-80 years), diagnosed between July 1994 and December 2019. An objective motor deficit was present in 50 cases, with the remaining 3 having a sensory deficit only. Forty cases underwent surgery, most often via the supraclavicular approach, while 13 cases did not undergo surgery because their deficit was longstanding and non-progressive., Results: One operated patient was lost in follow-up. An analysis of the medical records of 18 cases, including 15 operated cases found complete recovery in 4 cases, significant improvement in 9 cases and small improvement in 2 cases at a mean follow-up of 53 months (1-162 months). Thirty-four cases were reviewed in person, including 24 operated cases and evaluated with a mean follow-up of 135 months (36-284 months): the pain had disappeared in 21 cases, thenar atrophy persisted in 17 cases, which was associated with a claw-hand deformity in 3 cases, while 2 cases had an isolated claw-hand deformity. The patients were very satisfied with the procedure in 15 cases and satisfied in 9 cases. They evaluated the benefit of surgery at 87% and their upper limb function increased from 38% (10-60%) preoperatively to 77% (60-100%) at the review., Conclusion: Few studies in the literature have focused on true neurogenic TOS cases. The treatment is surgical in progressive cases; an anatomical anomaly is always present. Surgical treatment eliminates the pain and helps to stabilize or even partially resolve the deficit. Despite a moderate objective gain, the patients' feeling of functional improvement is important with a high satisfaction rate., Level of Evidence: IV, retrospective., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Background: The Petit-Morel method allows the treatment of developmental hip dysplasia in toddlers by combining gradual traction to achieve reduction followed by immobilisation during which pelvic osteotomy is performed. The objective of this study was to assess the radiographic and clinical outcomes in a retrospective cohort of patients., Hypothesis: The Petit-Morel method is associated with low rates of avascular necrosis and residual acetabular dysplasia at skeletal maturity, as well as with satisfactory medium-term clinical outcomes., Material and Methods: We conducted a single-centre retrospective study of 34 patients (35 hips) treated between 1997 and 2014. The radiological assessment criteria included an evaluation for avascular necrosis classified according to Kalamchi and MacEwan, the vertical centre edge (VCE) angle, femoral head sphericity according to Mose, and acetabular dysplasia at skeletal maturity according to Severin. Hip function was assessed by determining the Postel-Merle d'Aubigné (PMA) score., Results: Mean age at treatment was 19±4 months (range, 14-29). Mean follow-up was 11 years (range, 5-20). There were two failures including one case of recurrent dislocation requiring surgical reduction. Group II avascular necrosis occurred in 1 (3%) patient. Tönnis Grade IV dysplasia was significantly associated with resolving irregularity of the ossification centre, seen in 19 (54%) cases (p=0.002). In the 18 patients followed-up to skeletal maturity, with a mean follow-up of 15 years (range, 12-20 years), 17 hips were Severin Class I. The mean VCE angle was 29° (range, 15°-38°), and the head was spherical for 34 (98%) hips. The PMA score at last follow-up was excellent (17-18). The mean VCE angle was greater in all 5 patients who experienced pain during long walks (35° [range, 32°-37°]) than in the asymptomatic patients (28° [range, 15°-38°]) (p=0.009)., Discussion: The Petit-Morel method is a reliable treatment that provides good clinical and radiological outcomes. Overcorrection of the VCE angle was noted in the patients who experienced walking-related pain in adulthood., Level of Evidence: IV, retrospective observational cohort study., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Residual hip dysplasia may exist despite appropriate treatment of congenital hip dysplasia (CHD). The abnormalities chiefly affect the acetabulum and can lead to premature osteoarthritis. Although the main cause is delayed treatment of CHD, primary lesions are also possible and may be worsened by the initial treatment itself. Residual hip dysplasia must be detected during the follow-up of patients with CHD. The antero-posterior radiograph of the pelvis is the main diagnostic tool. However, the importance of non-ossified anatomical structures requires additional investigations such as arthrography and magnetic resonance imaging. The risk of premature osteoarthritis is difficult to predict based only on the imaging-study findings. Hip dysplasia is best treated before 5 years of age. The work-up at this age should allow determination of the best treatment. Surgery is required but should not be performed unnecessarily. The decision rests on the absence of improvement in the radiographic criteria and on the findings from additional imaging studies. The usual treatment is Salter's osteotomy, during which excessive anterior displacement should be avoided. At adolescence, the information provided by radiography in the coronal plane should be completed by a three-dimensional evaluation of the acetabulum and an assessment of the quality of the labrum. The shelf procedure has been proven to relieve pain and to significantly postpone the need for hip arthroplasty, when performed early, before the development of visible osteoarthritis, and on a congruent hip. Chiari's osteotomy has a role to play in complex dysplasia affecting both the acetabulum and the femur. Periacetabular osteotomy is getting more used thanks to cooperation between paediatric and adult orthopaedic surgeons. This osteotomy provides optimal correction in all three dimensions., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Purpose: To evaluate the AOSpine Thoracolumbar Spine Injury Classification System and if it is reliable and reproducible when applied to the paediatric population globally., Methods: A total of 12 paediatric orthopaedic surgeons were asked to review MRI and CT imaging of 25 paediatric patients with thoracolumbar spine traumatic injuries, in order to determine the classification of the lesions observed. The evaluators classified injuries into primary categories: A, B and C. Interobserver reliability was assessed for the initial reading by Fleiss's kappa coefficient (k F ) along with 95% confidence intervals (CI). For A and B type injuries, sub-classification was conducted including A0-A4 and B1-B2 subtypes. Interobserver reliability across subclasses was assessed using Krippendorff's alpha (α k ) along with bootstrapped 95% CIs. A second round of classification was performed one-month later. Intraobserver reproducibility was assessed for the primary classifications using Fleiss's kappa and sub-classification reproducibility was assessed by Krippendorff's alpha (α k ) along with 95% CIs., Results: In total, 25 cases were read for a total of 300 initial and 300 repeated evaluations. Adjusted interobserver reliability was almost perfect (kF = 0.74; 95% CI 0.71 to 0.78) across all observers. Sub-classification reliability was substantial (α k = 0.67; 95% CI 0.51 to 0.81), Adjusted intraobserver reproducibility was almost perfect (kF = 0.91; 95% CI 0.83 to 0.99) for both primary classifications and for sub-classifications (α k = 0.88; 95% CI 0.83 to 0.93)., Conclusion: The inter- and intraobserver reliability for the AOSpine Thoracolumbar Spine Injury Classification System was high amongst paediatric orthopaedic surgeons. The AOSpine Thoracolumbar Spine Injury Classification System is a promising option as a uniform fracture classification in children., Level of Evidence: III., (Copyright © 2021, The author(s).)

Introduction: Epidemiological studies of fractures of the spine in children are all old, mostly single-centre, with series spanning periods of 5 to 20 years., Hypothesis: As lifestyle is constantly changing, notably with an increase in sports activities and improvements in the prevention of road and household accidents, epidemiology has likely changed., Objective: To update the description of spinal trauma in children and adolescents compared to the existing literature., Material and Method: A multicentre cross-sectional study of spinal fracture, dislocation and spinal cord injury without radiological abnormality (SCIWORA) in children was carried out in 15 French university hospital centres, for a period of one year (2016)., Results: One hundred and sixty-five children were identified: 85 girls, 80 boys; mean age 11 years (range, 10 months-17 years); median, 12 years 6 months. One hundred and fifty-two children (92%) had fracture, 8 (5%) dislocation (including 7 C1-C2 rotary dislocations), and 5 (3%) SCIWORA. Fractures were multiple in 80 cases (49%), contiguous in 73 cases (91%) and non-contiguous in 7 (9%). Locations were cervical in 25 cases (15%), thoracic in 85 (52%), lumbar in 75 and sacral in 4 (2%). Fracture types comprised 234 vertebral compactions (78%), 25 burst fractures (8%), 5 chance fractures (2%), 2 odontoid fractures, and 33 other lesions. Causes comprised fall in 77 cases (47%), sports accidents in 56 (34%), road accidents in 29 (18%), and others in 3. In 52 cases (32%), there was ≥1 associated lesion: appendicular in 35 cases (67%), thoracic or abdominal in 31 (60%), and head in 16 (31%). Twenty-one cases had multiple lesions (40%). Eighteen cases showed neurological involvement (11%) including 5 SCIWORAs. Neurological complications were more frequent before 9 years of age., Conclusion: The epidemiology of spine fractures in children has slightly changed. There are now fewer cervical lesions. Causes are less often road accidents and more often sports accidents. Multi-level lesions remain frequent and the rate of neurological complications is around 10%. Compaction fracture is the most common type., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Children are physiologically protected against venous thromboembolism (VTE). Specific triggering events or contributing factors have been identified in the majority of reported cases, which differs from the adult pathology where 50% of the thromboses are considered "idiopathic". This is a rare disease in children with an estimated frequency of less than 1/1000. The risk is highest in neonates, then decreases and increases again around 13 years to reach the same level as adults at 16 years. The risk of VTE is clearly higher in certain situations: significant trauma, prolonged immobilization, central venous catheter, stay in intensive care unit, inherited thrombophilia, cancer, obesity, oral contraceptives, etc. Thromboprophylaxis should not be used systematically, even in adolescents. Proper hydration and early mobilization form the basis of mechanical thromboprophylaxis. A prescription is only given after careful analysis of the child's risk factors and the orthopedic context. Thrombotic risk assessment scores - which are based on expert opinion and large VTE registers but have not been evaluated in clinical studies - are currently the most reliable method to evaluate the thrombotic risk in children and to prescribe thromboprophylaxis. Low-molecular weight heparin are the most commonly used thromboprophylaxis agents in children, with good tolerance and efficacy., (Copyright © 2019. Published by Elsevier Masson SAS.)

Lipin-1 is a Mg 2+ -dependent phosphatidic acid phosphatase (PAP) that in mice is necessary for normal glycerolipid biosynthesis, controlling adipocyte metabolism, and adipogenic differentiation. Mice carrying inactivating mutations in the Lpin1 gene display the characteristic features of human familial lipodystrophy. Very little is known about the roles of lipin-1 in human adipocyte physiology. Apparently, fat distribution and weight is normal in humans carrying LPIN1 inactivating mutations, but a detailed analysis of adipose tissue appearance and functions in these patients has not been available so far. In this study, we performed a systematic histopathological, biochemical, and gene expression analysis of adipose tissue biopsies from human patients harboring LPIN1 biallelic inactivating mutations and affected by recurrent episodes of severe rhabdomyolysis. We also explored the adipogenic differentiation potential of human mesenchymal cell populations derived from lipin-1 defective patients. White adipose tissue from human LPIN1 mutant patients displayed a dramatic decrease in lipin-1 protein levels and PAP activity, with a concomitant moderate reduction of adipocyte size. Nevertheless, the adipose tissue develops without obvious histological signs of lipodystrophy and with normal qualitative composition of storage lipids. The increased expression of key adipogenic determinants such as SREBP1 , PPARG , and PGC1A shows that specific compensatory phenomena can be activated in vivo in human adipocytes with deficiency of functional lipin-1., (Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.)

The pig spine is widely used as a large animal model for preclinical research in human medicine to test new spinal implants and surgical procedures. Among them, pedicle screw is one of the most common method of fixation of those implants. However, the pedicle of the porcine vertebra is not as well defined and not as large as the pedicle of the human vertebra. Therefore, the position of the screw should be adapted to the pig and not merely transposed based on the literature on humans. The purpose of this study is to determine the characteristics of the optimum implantation corridors for pedicle screws in the thoracolumbar spine of piglets of different ages using computed tomography (CT) and to determine the size and length of these corridors in pigs of different ages. CT scans from five groups of age: 6, 10, 14, 18, and 26 weeks were reviewed. For each thoracolumbar vertebrae, the pedicle width, pedicle axis length, and the pedicle angle was measured for the left and right pedicle. A total of 326 thoracic vertebrae and 126 lumbar vertebrae were included in the study. Pedicles are statistically larger but not longer for the lumbar vertebrae. An important variation of the pedicle angle is observed along the spine. In all pigs, an abrupt modification of the pedicle angle between T10 and T11 was observed, which corresponds to the level of the anticlinal vertebra which is the vertebra for which the spinous process is nearly perpendicular to the vertebral body. In conclusion, this study provides a quantitative database of pedicle screw implantation corridors in pigs of different ages. When using pedicle screws in experimental studies in pigs, these results should be considered for selecting the most suitable implants for the study but also to ensure a correct and safer screw position. Improving study procedures may limit postoperative complications and pain, thereby limiting the use of live animals.

The porcine model is frequently used during development and validation of new spinal devices, because of its likeness to the human spine. These spinal devices are frequently composed of pedicle screws with a reputation for stable fixation but which can suffer pullouts during preclinical implantation on young animals, leading to high morbidity. With a view to identifying the best choices to optimize pedicle screw fixation in the porcine model, this study evaluates ex vivo the impact of weight (age) of the animal, the level of the vertebrae (lumbar or thoracic) and the type of screw anchorage (mono- or bi-cortical) on pedicle screw pullouts. Among the 80 pig vertebrae (90- and 140-day-old) tested in this study, the average screw pullout forces ranged between 419.9N and 1341.2N. In addition, statistical differences were found between test groups, pointing out the influence of the three parameters stated above. We found that the the more caudally the screws are positioned (lumbar level), the greater their pullout resistance is, moreover, screw stability increases with the age, and finally, the screws implanted with a mono-cortical anchorage sustained lower pullout forces than those implanted with a bi-cortical anchorage. We conclude that the best anchorage can be obtained with older animals, using a lumbar fixation and long screws traversing the vertebra and inducing bi-cortical anchorage. In very young animals, pedicle screw fixations need to be bi-cortical and more numerous to prevent pullout.

Background: Mucopolysaccharidosis type I (MPS-I) is a lysosomal storage disorder characterized by progressive multi-organ disease. The standard of care for patients with the severe phenotype (Hurler syndrome, MPS I-H) is early hematopoietic stem cell transplantation (HSCT). However, skeletal disease, including hip dysplasia, is almost invariably present in MPS I-H, and appears to be particularly unresponsive to HSCT. Hip dysplasia may lead to pain and loss of ambulation, at least in a subset of patients, if left untreated. However, there is a lack of evidence to guide the development of clinical guidelines for the follow-up and treatment of hip dysplasia in patients with MPS I-H. Therefore, an international Delphi consensus procedure was initiated to construct consensus-based clinical practice guidelines in the absence of available evidence., Methods: A literature review was conducted, and publications were graded according to their level of evidence. For the development of consensus guidelines, eight metabolic pediatricians and nine orthopedic surgeons with experience in the care of MPS I patients were invited to participate. Eleven case histories were assessed in two written rounds. For each case, the experts were asked if they would perform surgery, and they were asked to provide information on the aspects deemed essential or complicating in the decision-making process. In a subsequent face-to-face meeting, the results were presented and discussed. Draft consensus statements were discussed and adjusted until consensus was reached., Results: Consensus was reached on seven statements. The panel concluded that early corrective surgery for MPS I-H patients with hip dysplasia should be considered. However, there was no full consensus as to whether such a procedure should be offered to all patients with hip dysplasia to prevent complications or whether a more conservative approach with surgical intervention only in those patients who develop clinically relevant symptoms due to the hip dysplasia is warranted., Conclusions: This international consensus procedure led to the construction of clinical practice guidelines for hip dysplasia in transplanted MPS I-H patients. Early corrective surgery should be considered, but further research is needed to establish its efficacy and role in the treatment of hip dysplasia as seen in MPS I.

Purpose: The purpose of this study was to provide the readers with a reliable source of animal models currently being utilized to perform state-of-the-art scoliotic research., Materials and Methods: A comprehensive search was undertaken to review all publications on animal models for the study of scoliosis within the database from 1946 to January 2011., Results: The animal models have been grouped under specific headings reflecting the underlying pathophysiology behind the development of the spinal deformities produced in the animals: genetics, neuroendocrine, neuromuscular, external constraints, internal constraints with or without tissue injury, vertebral growth modulation and iatrogenic congenital malformations, in an attempt to organize and classify these multiple scoliotic animal models. As it stands, there are no animal models that mimic the human spinal anatomy with all its constraints and weaknesses, which puts it at risk of developing scoliosis. What we do have are a multitude of models, which produce spinal deformities that come close to the idiopathic scoliosis deformity., Conclusion: All these different animal models compel us to believe that the clinical phenotype of what we call idiopathic scoliosis may well be caused by a variety of different underlying pathologies.

We implemented an experimental model of asymmetrical compression loading of the vertebral end plate (VEP) in vivo. The macroscopic permeability of the VEP was measured. We hypothesized that static asymmetrical loading on vertebrae altered the macroscopic permeability of the VEP. In scoliosis, solute transport to and from the disc is dramatically decreased especially at the apical intervertebral disc. The decrease in permeability could be induced by mechanical stress. Nine skeletally immature pigs were instrumented with left pedicle screws and compression rod at the T5/T6 and L1/L2 levels. After 3 months, three cylindrical specimens of the VEP were obtained from each of the tethered levels. A previously validated method for measuring permeability, based on the relaxation pressure due to a transient-flow rate was used. A pistoning device generated a fluid flow that fully saturated the cylindrical specimen. The decrease in upstream pressure was measured using a pressure transducer, which allowed the macroscopic permeability to be derived. A microscopic study completed the approach. Overall macroscopic permeability was lower for the tethered VEPs than for the VEPs of the control group, respectively -47% for flow-in (p = 0.0001) and -46% for flow-out (p = 0.0001). In the tethered group, macroscopic permeability of the specimens from the tethered side was lower than macroscopic permeability of those from the non-tethered side, -39% for flow-out (p = 0.024) and -47% for flow-in (p = 0.13). In the control group, the macroscopic permeability was greater in the center of the VEP than in its lateral parts for flow-out (p = 0.004). Macroscopic permeability of the center of the VEPs was greater for flow-out than for flow-in (p = 0.02). There was no significant difference between thoracic and lumbar. This study demonstrated that compression loading applied to a growing spine results in decreased permeability of the VEP. This result could be explained by local remodeling, such as calcification of the cartilage end plate or sclerosis of the underlying bone.

Achondroplasia and thanatophoric dysplasia are human chondrodysplasias caused by mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. We have developed an immortalized human chondrocyte culture model to study the regulation of chondrocyte functions. One control and eight mutant chondrocytic lines expressing different FGFR3 heterozygous mutations were obtained. FGFR3 signaling pathways were modified in the mutant lines as revealed by the constitutive activation of the STAT pathway and an increased level of P21(WAF1/CIP1) protein. This model will be useful for the study of FGFR3 function in cartilage studies and future therapeutic approaches in chondrodysplasias.

Rigid congenital kyphosis in myelomeningocele is associated with an important morbidity with skin breakdown, recurrent infection, and decreased function. Kyphectomy is the classic treatment to restore spinal alignment; however, surgery is associated with an important morbidity and long-term correction is uncertain. The authors retrospectively reviewed 9 patients with a mean age of 8.8 years who underwent a two stage surgical procedure: first a posterior kyphectomy with a modified Dunn-McCarthy fixation consisting of lumbar pedicle screws and long S-shape rods buttressing the anterior sacrum. Then a second stage done several weeks later consisting of a thoraco-abdominal approach to the spine with an inlay strut graft classically from T10-S1. The mean follow-up was 34 months (range 1-5 years). The kyphosis was corrected from a mean of 110 degrees of Cobb angle (range 70-130 degrees) to 15 degrees after surgery (45-0 degrees). There was no instrumentation failure, no loss of correction and no pseudarthrosis. Complications consisted of one intra-operative cardiac arrest fortunately reversible, a wound necrosis, one deep venous thrombosis and one late aseptic bursitis on the posterior hardware. Congenital kyphosis in myelomeningocele can be treated successfully with an initial posterior approach correction and instrumentation followed by an anterior approach allowing for anterior inlay impacted structural graft. The authors believe that this technique improves biomechanical and biological fusion mass anteriorly and will prevent late instrumentation failure and loss of correction.

Congenital scoliosis is the most frequent congenital deformity of the spine. Congenital curvatures are due to anomalous development of the vertebrae (failure of formation and/or segmentation). Congenital scoliosis is believed to be related to an insult to the fetus during spine embryological development, and associated malformations (heart, spinal cord, kidney.) are frequently observed. A perfect understanding of the natural history of the deformity and the treatment principles will allow best management of these complex spine deformities. New imaging techniques like three-dimensional computed tomography (CT) and magnetic resonance imaging (MRI) are important tools for analyzing the underlying deformity and understanding the evolution of the complex deformities. The mainstay of treatment is either observation or, in case of curve progression (>10 degrees /year), surgery. Different surgeries are described with two main principles: (1) prophylactic surgeries like hemiepiphysiodesis or in situ fusions that will prevent worsening or allow progressive correction over time, and (2) corrective surgeries, with spinal fusion with or without spinal resection. Exceptional procedures (e.g. spinal column resection or halo distraction) can be attempted in cases of very severe deformity. Congenital curves must be carefully observed to choose the least invasive procedure at the right time and to minimize spinal cord risks.