Biocompatibility of nano/micro-sized pyrophyllite particles by pulmo, liver, kidney and gastric mucosis cells.

Pyrophyllite is the least studied natural clay in terms of its potential in biomedical applications, although there are many deposits of this aluminosilicate around the world. Genotoxicity study was performed in vitro for this mineral. Subsequently, Wister rats were exposed to the pyrophyllite micronized to below 100 µm. After the exposure period, histology of the lung, liver, kidney and gastric tissues were performed, followed by the stereological and hematological analysis. The physicochemical analyses revealed typical XRD characteristics of pyrophyllite clay with particle-size distribution ranging 50 nm-100 µm with stable mineral composition and unique buffering property to pH around 8. The results showed that there were no cytotoxic effects on to THP-1 cells, or genotoxicity of pyrophyllite measured by the Comet assay. In vivo studies are accompanied by the thorough physicochemical characterization of the micronized pyrophyllite. Histology of the lung tissue proved presence of an inflammatory reaction. On the other hand, gastric tissue has shown the selective accumulation of nanoparticles in enterocytes of the stomach only, as supported by ultrastructural analysis. Liver and kidney tissues have shown tolerability for pyrophyllite particles. The results give directions for further comprehensive studies of potential biomedical applications of the pyrophyllite.

Experience and volume are determinantive factors for operative management of supracondylar humeral fractures in children.

BACKGROUND: We compared radiographic and operative results of pediatric patients undergoing surgical treatment of displaced supracondylar humeral fracture (SCHF) according to the surgeon's experience. METHODS: During an 11-year period (2006-2016), we reviewed the medical records of 236 patients operated on for Gartland III SCHF in our institution. Operative (operative time, time to implants removal) and radiographic parameters (Baumann and lateral capitellohumeral angles) were assessed. A malalignment was defined if there was a difference in the Baumann angle or lateral capitellohumeral angles >15° or if malrotation existed compared with normative values. We compared surgeon experience and volume (number of patients operated on by year). RESULTS: In patients operated on by less experienced surgeons (<1 year, n = 69), operative time (61 vs. 41 minutes) and time to implant removal (48 vs. 40 days) were significantly longer (P < .001). Radiographic parameters did not differ between less and more experienced surgeons. Operative parameters improved through the 20 first cases of the younger surgeons. In surgeons managing fewer than 5 patients per year, malalignment and conversion to open reduction were more frequent (all P < .05). CONCLUSION: Experience and volume are 2 crucial parameters influencing the quality of management of pediatric patients undergoing surgical treatment for displaced SCHF. They should be taken into account in daily practice, especially when making the decision to operate on these patients out of day time.

Medial patellofemoral ligament reconstruction in children: do osseous abnormalities matter?

PURPOSE: Management of post-traumatic patellar instability in children with osseous abnormalities is challenging because of the presence of an open physis. The aim of our study was to compare the rate of recurrence after isolated reconstruction of the medial patellofemoral ligament (MPFL) in children with or without osseous abnormalities. METHODS: The medical records of 25 children (27 knees) with recurrent patellar dislocation were reviewed. Each child underwent an isolated reconstruction of the MPFL using a hamstring graft. At the last follow-up, a clinical and radiographic evaluation was performed, including assessment of functional outcomes based on the Kujala score. Patients were compared in terms of the occurrence of a pre-existing osseous abnormality. RESULTS: The mean age at the time of the surgery was 13.8 years. Eleven patients had trochlear dysplasia (40%), three had a patella alta (11%) and seven had an increased TT-TG (26%). The recurrence rate was 3.7% (one patient), after a mean follow-up of 41.1 months. Recurrence was not more frequent in patients with preoperative anatomical predisposing factors. The mean Kujala score was 95. The mean time to return to practicing sports was 7.1 months. CONCLUSIONS: Isolated MPFL reconstruction is an effective option for the management of post-traumatic patellofemoral instability in skeletally immature patients. The results of this technique seem to be independent on either proximal or distal misalignments such as trochlear dysplasia, patella alta, or increased TT-TG.

Pseudoaneurysm of anterior tibial artery following a diaphyseal fracture of the tibia mimicking a malignant bone tumor.

Pseudoaneurysms of the lower limb are rare and frequently iatrogenics complications. Closed traumas are likely to generate lesions of the arterial wall, which generally become symptomatic at a later stage. The diagnosis of such vascular lesion is difficult because the symptomatology and the onset can be delayed. We herein report the case of a 15-year-old patient in whom the diagnosis of pseudoaneurysm of the anterior tibial artery was made 5 months after a non-displaced closed fracture of the tibial shaft. The radiographs were evocative of a malignant bone tumor. The study of vessels by a contrast-enhanced CT-scan enabled us to diagnose the pseudoaneurysm. Before the occurrence of late onset swelling, a history of trauma must be sought, even old.

Efficiency of Polyoxometalate-Based Mesoporous Hybrids as Covalently Anchored Catalysts.

Polyoxometalate (POM) hybrids have been covalently immobilized through the formation of amide bonds on several types of mesoporous silica. This work allows the comparison of three POM-based mesoporous systems, obtained with three different silica supports in which either the organic functions of the support (amine vs carboxylic acid) and/or the structure of the support itself (SBA-15 vs mesocellular foams (MCF)) were varied. The resulting POM-based mesoporous systems have been studied in particular by high resolution transmission electronic microscopy (HR-TEM) in order to characterize the nanostructuration of the POMs inside the pores/cells of the different materials. We thus have shown that the best distribution and loading in POMs have been reached with SBA-15 functionalized with aminopropyl groups. In this case, the formation of amide bonds in the materials has led to the nonaggregation of the POMs inside the channels of the SBA-15. The catalytic activity of the anchored systems has been evaluated through the epoxidation of cyclooctene and cyclohexene with H2O2 in acetonitrile. The reactivity of the different grafted POMs hybrids has been compared to that in solution (homogeneous conditions). Parallels can be drawn between the distribution of the POMs and the activity of the supported systems. Furthermore, recycling tests together with catalyst filtration experiments during the reaction allowed us to preclude the hypothesis of a significant leaching of the supported catalyst.

Halide-free CO2 cycloaddition onto styrene oxide catalysed by first row transition-metal derivatives of polyoxotungstates.

Quaternary ammonium salts of metal derivatives of polyoxometalates [XW11O39M(H2O)]n- (X = P, Si; M = Cr, Mn, Co, Ni, Zn) were successfully tested instead of quaternary ammonium halides as catalysts in the cycloaddition of CO2 to styrene oxide. Remarkably, they gave very satisfactory yields of styrene carbonate at moderate temperature (80 °C).

Juvenile hallux valgus: Comparison of three types of osteotomy and medium-term postoperative results.

BACKGROUND: There is no consensus on the treatment of juvenile hallux valgus (JHV). Numerous surgical techniques have been described, none of which has been proven to be superior and the mid-term results of these methods are not well known. Our objective was to compare the mid-term clinical, radiographic, and functional results of three metatarsal osteotomy techniques. METHODS: Patients under 18 years of age operated on for JHV between January 2010 and December 2019 were included in this multicenter retrospective study. Patients were excluded if they had non-idiopathic hallux valgus or if their postoperative follow-up was less than 3 years. The surgical techniques used were metatarsal osteotomies: basimetatarsal, scarf, or distal. During follow-up visits, we collected HMIS-AOFAS (Hallux Metatarsophalangeal Interphalangeal Scale-American Orthopedic Foot and Ankle Society) and Visual Analogue Scale (VAS) scores, acquired radiographs, and recorded complications and recurrences. Secondarily, the study population was stratified according to physis status (open vs. closed). RESULTS: During the study period, 18 patients (26 feet) met the inclusion criteria. The median postoperative follow-up was 6.5 (4.1) years. At the end of follow-up, the median HMIS score was 79.0 (20.0), the mean hallux valgus angle (HVA) improvement was 13.2° (16.8), and the complication and recurrence rates were 31 % and 23 %, respectively. There was no significant difference in the outcome measures between the three techniques or any difference according to physis status at the time of surgery. DISCUSSION AND CONCLUSION: The functional and radiographic results of metatarsal osteotomies are good in the medium term, regardless of the osteotomy site. Our results are comparable to those published in the literature. As our sample size was limited, it did not lead to the identification of statistically significant differences.

Covalent grafting of organic-inorganic polyoxometalates hybrids onto mesoporous SBA-15: a key step for new anchored homogeneous catalysts.

Covalent grafting of heteropolyanions hybrids B,α-[As(III)W9O33{P(O)(CH2CH2CO2H)}2](5-) on 3-aminopropyl functionalized SBA-15 has been achieved through the formation of peptide bonds. The covalent link has been confirmed by using IR and (13)C CP MAS NMR spectroscopies. Electrostatic interactions between carboxylate and protonated amines have been discarded on the basis of the retention of POMs after repeated washings of the resulting material by ionic liquid (bmimCl). This is the first example of anchored monovacant polyoxometalates (POM) in which nucleophilic oxygen atoms are still available after incorporation into mesoporous supports. Further characterization of the textural properties of grafted materials has shown that they still retain an important mesoporosity, which is compatible with their potential use in heterogeneous catalysis. Such systems are thus interesting candidates for the preparation of anchored homogeneous catalysts in which the POMs would play the role of polydentate inorganic ligands for the active centers.

Athletic children: Guidelines and monitoring in pediatric orthopedic surgery.

In day-to-day practice pediatric orthopedic surgeons often come up against the question of sport. The aim of the present study was to analyze the relationship between sport and childhood, with 3 questions: (1) What are the benefits of sport for children? (2) How to manage high-level child athletes? And (3) What sports are possible after major orthopedic surgery? Sports provide many benefits for children, and are to be encouraged. Sixty minutes' moderate to intense physical activity per day benefits motor development and bone mineralization and reduces the risk of obesity. On the other hand, excessive sports activity, as encountered in high-level sport, can be harmful for the child's development. The amount of training should not exceed a certain threshold in terms of hours per week according to age. Surgical treatment of sport-related traumatic lesions does not necessarily accelerate return to sport: indications need to be reasonable, despite pressure from the patient's circle. Sports are possible after major orthopedic surgery, although return to sport tends to be delayed and the level is lower than preoperatively.

Tibia Valga Correction by Extraperiosteal Fibular Release in Multiple Exostosis Disease.

Genu valgum is a frequent deformity encountered in Multiple Hereditary Exostosis (MHE) patients. If left untreated, lower limb deformity leads to poor functional outcomes in adulthood. Our hypothesis was that in some cases, fibular shortening would lead to a lateral epiphysiodesis-like effect on the tibia. We herein report the case of a 6-year-old child with MHE who underwent extraperiosteal resection of the fibula for tibia valga correction. To obtain the lateral release of the calf skeleton, resection included inter-tibio-fibular exostosis along with proximal fibular metaphysis and diaphysis without any osseous procedure on the tibia. Gradual improvement of the valgus deformity occurred during follow-up (HKA from 165° preop to 178° at 27-month follow-up). Lateral release of the fibula led to an increase in the fibula/tibia index (from 93% preop to 96% at follow-up). Studying fibular growth in MHE patients could help understand how valgus deformity occurs in these patients. Even if encouraging, this result is just the report of a unique case. Further research and a larger series of patients are required to assess fibular release as a valuable option to treat valgus deformity in MHE.

Treatment of knee sprains in children.

The incidence of knee sprains in children is steadily increasing. Skeletal immaturity and anatomical features of the child's ligamentous structures explain the frequency of bone avulsions in young children. Peripheral ligament injuries are the most common and often benign. Nevertheless, associated injuries of the cruciate or patellofemoral ligament(s) are not rare and must not be missed. Age is a determining factor in diagnostic guidance. Anterior intercondylar tibial eminence fractures, otherwise known as tibial spine fractures (TSF), usually occur in young children. Ligamentous distension at the time of the accident would explain the residual laxity that can affect the prognosis of these fractures. The treatment of interstitial ruptures of the ACL follows recommendations that are becoming clearer through multicentric studies. Reparation techniques, historically rejected as ineffective, have again become topical under specific conditions with the aim of preserving the native ACL and its proprioceptive receptors, which are essential in children. ACL reconstruction techniques have made progress in children, especially with techniques adapted from adults. Preservation of growth plates remains pertinent, especially at the femur to avoid growth disorders, thus highlighting the important role paediatric orthopaedic surgeons have in the management of these knee sprains.

Alternative ball-milling synthesis of vanadium-substituted polyoxometalates as catalysts for the aerobic cleavage of C-C and C-O bonds.

Vanadium-substituted phosphomolybdic acids (H3+x[PMo12-xVxO40], denoted as Vx) are well-known oxidation catalysts that are generally prepared by the hydrothermal treatment of MoO3 and V2O5 in the presence of H3PO4. This synthesis procedure is highly energy consuming and the Vx yields are not always acceptable. In the present work, an alternative hybrid mechanochemical/hydrothermal synthesis of Vx is proposed, comprising the ball-milling of MoO3 and V2O5, followed by a hydrothermal attack. The resulting materials, with 2 ≤ x ≤ 3, obtained from this new route were compared, in terms of yield, energy consumption and catalytic activity, with a reference V3 sample prepared through a conventional hydrothermal treatment. The ball-milling step proved to lead not only to a shorter and far more energy-saving synthesis procedure, but also to high yields of Vx. Moreover, Vx from this alternative route proved to be generally more active than the conventionally prepared V3 in the aerobic oxidative cleavage of C-O and C-C bonds in 2-phenoxyacetophenone, used herein as a lignin model compound.

Chromium-Salophen as a Soluble or Silica-Supported Co-Catalyst for the Fixation of CO2 Onto Styrene Oxide at Low Temperatures.

Addition of a soluble or a supported CrIII-salophen complex as a co-catalyst greatly enhances the catalytic activity of Bu4NBr for the formation of styrene carbonate from styrene epoxide and CO2. Their combination with a very low co-catalyst:Bu4NBr:styrene oxide molar ratio = 1:2:112 (corresponding to 0.9 mol% of CrIII co-catalyst) led to an almost complete conversion of styrene oxide after 7 h at 80°C under an initial pressure of CO2 of 11 bar and to a selectivity in styrene carbonate of 100%. The covalent heterogenization of the complex was achieved through the formation of an amide bond with a functionalized {NH2}-SBA-15 silica support. In both conditions, the use of these CrIII catalysts allowed excellent conversion of styrene already at 50°C (69 and 47% after 24 h, respectively, in homogeneous and heterogeneous conditions). Comparison with our previous work using other metal cations from the transition metals particularly highlights the preponderant effect of the nature of the metal cation as a co-catalyst in this reaction, that may be linked to its calculated binding energy to the epoxides. Both co-catalysts were successfully reused four times without any appreciable loss of performance.

Vanadium-Substituted Phosphomolybdic Acids for the Aerobic Cleavage of Lignin Models-Mechanistic Aspect and Extension to Lignin.

This work deals with the aerobic oxidative cleavage of C-C and C-O bonds catalyzed by the Keggin-type phosphovanadomolybdic acid (H6[PMo9V3O40], noted H6PV3). The latter was synthesized by an adapted hydrothermal procedure classically used for lower vanadium content and was tested as a catalyst for the aerobic cleavage of 2-phenoxyacetophenone (noted K1HH) and 1-phenyl-2-phenoxyethanol (A1HH) used as two lignin models. The operative conditions (solvent, catalytic loading, etc.) were adjusted on K1HH and extrapolated to A1HH. The cleavage of the alcohol model required more drastic conditions and therefore further optimization. Preliminary attempts on an Organosolv wheat straw lignin were performed too. From the kinetic study, high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) data, a mechanism of the cleavage of both models was proposed.

Pelvic fractures in children (pelvic ring and acetabulum).

Pelvic fractures in children are rare and often the result of high-energy trauma. The possibility of associated lesions cannot be ignored. Treatment at a specialized children's hospital is a must. The multidisciplinary care team must include a paediatric orthopaedic surgeon. In the emergency room, the surgeon contributes to haemodynamic stabilization of the child by reducing and stabilizing posterior arch fractures and restoring the skeletal cohesion to make it easier to move the child and allow other examinations to be performed. Imaging modalities are used to determine the stability of the pelvic ring fracture, the risk of epiphysiodesis of an acetabulum fracture if the triradiate cartilage is open and the joint congruency if the triradiate cartilage is closed. Internal fixation can be used if surgery is being performed for associated non-orthopaedic injuries. Most vertically stable fractures are treated non-surgically. Fractures that are unstable vertically will require surgical treatment. Treatment of acetabulum fractures depends on the status of the triradiate cartilage. In older children, it is similar to the treatments used in adults. In children with open growth plates, the goal is to make sure the acetabulum continues growing. In all cases, the patients must be instructed to start physical therapy as soon as possible. Full recovery can be expected after stable pelvic fractures. Unstable pelvic fractures can lead to sequelae, the severity of which depend on the residual pelvic displacement and involvement of the growth plates that can cause epiphysiodesis. Surgery to correct these deformities is challenging. The most serious occur when the vertical displacement of the hemipelvis must be corrected. After an acetabulum fracture, removal of the growth blocker can be done in children under 10 years of age. In older children, acetabular dysplasia requires periacetabular osteotomy.

Can the TrueLok Hexapod System™ be used to accurately correct lower limb deformity in children?

INTRODUCTION: Progressive bone lengthening in children can be done using an external fixator, a lengthening nail, or plate with screws. The TrueLok Hexapod System™ (TL-HEX™) is the newest hexapod external fixator on the market. We hypothesized that the TL-HEX™ can accurately correct lower limb deformities in children. The goal of this study was to evaluate the clinical and radiographic outcomes after correcting lower limb deformities in children using the TL-HEX™ system. MATERIAL AND METHODS: Data from 58 limbs that underwent bone lengthening with the TL-HEX™ were analyzed for this retrospective, single-center study. The average patient age was 11.4 years. The femur was lengthened in 23 limbs and the tibia in 35. The outcomes were evaluated using long leg standing radiographs preoperatively and at the final assessment. The variables of interest were the mechanical axis deviation (MAD), mechanical lateral distal femoral angle (mLDFA), mechanical lateral proximal tibia angle (mMPTA), healing index (HI) and accuracy of the correction. The complications were graded on a 4-point scale summarizing three broad goals: planned correction, duration of treatment and sequelae. The accuracy of the correction was defined as the difference between the planned correction and the actual correction achieved. RESULTS: The mean HI was 37 days/cm. Significant correction was achieved for leg length discrepancy (LLD) (60 mm vs. 20 mm; p<0.01) and mLDFA (88.6° vs. 89.9°; p=0.04) but not the MAD (17.7 vs. 14.7; p= 0.17) or mMPTA (87.3 vs. 88.1; p=0.08). In the entire cohort, the difference from planned was 12.5 mm (p<0.01) for lengthening, 1.3° for the mLDFA (p=0.5) and 3° for the mMPTA (p=0.02). Relative to the initial goal, the mean lengthening achieved was 118%. In the sub-group where the plan did not need to be modified, the accuracy of the correction was better. There were 40 complications (69%). CONCLUSION: The TL-HEX™ is an effective and accurate system. The complication rate associated with its use is the same as other hexapod external fixators. Surgeons and patients must be aware of the high complication rate, which may require the plan to be modified and could potentially compromise the outcome.

Congenital dislocated spine: implications for orthopaedic management.

BACKGROUND: Congenital dislocation of the spine (CDS) is a rare malformation due to a developmental failure of the spine and the spinal cord at a single spinal level. New embryological and physiopathological findings define CDS as an autonomous entity compared with multilevel pathologies. The severity of CDS neurological outcome requires its treatment by experienced pediatric spine surgeons in a pediatric specialty hospital. This report aims to propose a comprehensive orthopaedic management strategy and operative technique of CDS in 6 new patients. METHODS: The records of patients treated at our institution for congenital anomalies of the spine were reviewed in a retrospective study. Inclusion criteria were extracted from the actual context of new embryologic theories: single level involvement; sudden mainly sagittal vertebral displacement with anterior translation of the entire cranial vertebral column on the caudal vertebrae ("step-off sign"); underlying spinal malformation at a clearly distinct level; spinal cord intact both cranial and caudal to the malformation; possibility of malformed aspect of the 2 involved vertebrae. Demographic data, family, and clinical history were collected. Complete set of plain radiographs and modern imaging computed tomography and magnetic resonance imaging were analyzed. RESULTS: Six children treated between 1993 and 2007 have been classified as CDS. The mean follow-up to date of the 4 patients alive after the last corrective surgery is 9.8 years (range, 1-14.6 years). All patients alive have at follow-up solid stable fusion and no progression of spinal deformity. Two of the patients are independent walkers. CONCLUSIONS: The neurological involvement of CDS if present initially is the consequence of an associated spinal cord malformation without mechanical factor. Adaptation of the therapeutic strategy may avoid secondary neurological damage. Parents should be counseled as soon as the diagnosis is made, the obstetrical and postnatal orthopaedic management has to be adapted. Stabilization of the spine including very early cast immobilization and an early instrumented decompression-stabilization with circumferential fusion in 1 stage is required.

Symptomatic os trigonum in children.

BACKGROUND: Symptomatic os trigonum is a rare condition well described in adults responsible for chronic ankle pain. To date there is no published case of successfully managed symptomatic os trigonum in children. METHODS: We retrospectively reviewed 4 paediatric patients (11-17) successfully operated on for a symptomatic os trigonum through a postero medial approach. One case was bilateral. RESULTS: Pain relief was postoperatively obtained in all cases. All of the patients were able to return to physical activities after 3 months. The mean follow up was 12 months. CONCLUSION: Symptomatic os trigonum may be responsible for chronic ankle pain in children and adolescents as well as in adults. The surgical treatment is effective in children.

Assessment of elastic coefficients of child cortical bone using resonant ultrasound spectroscopy.

The assessment of the anisotropic elastic properties of non-pathological child cortical bone remains a challenge for the biomechanical engineering community and an important clinical issue. Resonant ultrasound spectroscopy (RUS) can be used to determine bone stiffness coefficients from the mechanical resonances of bone specimens. Here, a RUS protocol was used on 7 fibula specimens from children (mean age 14 ±â€¯3 years) to estimate the whole elastic stiffness tensor of non-pathological child cortical bone considered as orthotropic. Despite a small number of sample, results are consistent with this hypothesis, even if a trend towards transverse isotropy is discussed. Indeed, the average values of the 9 independent stiffness coefficients obtained in this study for child bone are: C11 = 16.73 ±â€¯0.19 GPa, C22 = 16.19 ±â€¯0.12 GPa, C33 = 24.47 ±â€¯0.30 GPa, C44 = 4.14 ±â€¯0.08 GPa, C55 = 4.16 ±â€¯0.07 GPa, C66 = 3.13 ±â€¯0.05 GPa, C12 = 10.14 ±â€¯0.20 GPa, C13 = 10.67 ±â€¯0.27 GPa, C23 = 10.25 ±â€¯0.14 GPa.

A surfactant-assisted preparation of well dispersed rhodium nanoparticles within the mesopores of AlSBA-15: characterization and use in catalysis.

Well dispersed and efficient Rh(0) hydrogenation catalysts were obtained by the reduction of Rh(III)-exchanged mesoporous aluminosilicates by sodium borohydride in the presence of N,N-dimethyl-N-cetyl-N-(2-hydroxyethyl) ammonium chloride.