The Duration of Hardware Retention After Radiologic Union of Surgically Treated Femoral Neck Fractures in Children May Predict the Aggravation or Occurrence of Avascular Necrosis of the Femoral Head or Neck After Hardware Removal.

BACKGROUND: The incidence of aggravation or occurrence of avascular necrosis (AVN) following hardware removal in surgically treated pediatric femoral neck fractures who achieved radiologic consolidation is unknown. This study aimed to investigate the risk factors for this complication. METHODS: Seventy-one pediatric (mean age: 9.8±3.9 y) were retrospectively analyzed. Risk factors (age, sex, laterality, severity of initial displacement, type of fracture, time from trauma to reduction, reduction and fixation method, quality of reduction, time required to achieve radiologic union, duration of hardware retention, presence of AVN before hardware removal and follow-up time) were recorded. The severity of AVN was assessed based on radiographs with Ratliff's classification. RESULTS: Following hardware removal, the aggravation/occurrence of AVN was detected in 11 hips (15.5%). Among the 5 hips (7%) with aggravation of AVN, 1 (1.4%) with type II AVN and 3 (4.2%) with type III AVN exhibited aggravation of type I AVN, while the remaining hip (1.4%; type I) showed enlargement of the involved AVN area. Six hips (8.5%) developed AVN following hardware removal: 2 (2.8%) were classified as type I and 4 (5.6%) as type III. Receiver operating characteristic curve analysis indicated that hardware retention >7 months after union is associated with a decreased rate of aggravation or occurrence of AVN of the femoral neck or head following hardware removal. CONCLUSIONS: The incidence of aggravation or occurrence of AVN following hardware removal in surgically treated pediatric femoral neck fractures is 15.5%; hardware retention >7 months after radiologic union may reduce the risk of aggravation or occurrence of AVN of the femoral neck or head postimplant removal. LEVEL OF EVIDENCE: Level III.

Is there an alternative to the Delbet-Colonna classification? Introduction and reliability assessment of a new classification system for paediatric femoral neck fractures: preliminary results.

PURPOSE: The purpose of this study was to introduce a new classification system for paediatric femoral neck fractures (PFNFs) and to evaluate its reliability. METHODS: Two hundred and eight unilateral PFNFs (mean patient age: 9.0 ± 4.8 years) were included. Based on preoperative radiographs, the new classification system distinguished PFNFs without anterior or posterior translation (Type I), PFNFs with anterior (Type II) or posterior (Type III) translation, PFNFs with a comminuted medial or posterior column (Type IV), and subtrochanteric femoral fractures (SFFs; Type V). Radiographs were evaluated twice with an interval of two weeks by 19 raters with different specialties, experiences and geographical origins. The results were compared with a selection of 50 patient age-matched unilateral PFNFs and SFFs (mean patient age: 9.1 ± 4.9 years). These were graded twice by the same graders according to the Delbet-Colonna (D-C) classification. RESULTS: Four radiologists and 15 paediatric orthopaedic surgeons from Europe and Asia graded the radiographs. Fair agreement was found between radiologists (κ = 0.296 ± 0.01) and surgeons (κ = 0.3 ± 0.005) (P = 0.17), although more experienced surgeons performed better than less experienced ones; a similar fair assessment was found for raters from Europe (κ = 0.309 ± 0.021) and Asia (κ = 0.3 ± 0.006) and for type II, III and IV fractures; the κ value in the first evaluation (0.309) was similar to that in the second evaluation (0.298). The overall κ value of the D-C classification subtypes was significantly higher (0.599 ± 0.217) than that of the new classification, 0.326 ± 0.162 (t = 3.190 P = 0.005). CONCLUSIONS: The new classification system showed fair reliability relative to the D-C classification. The reliability of the new classification system was not affected by the specialty or geographic origin of the rater or the evaluation round, only by rater experience level. The concordance was worse for PFNFs with anterior or posterior translation or with a comminuted medial or posterior columns.

Automatic and Quantitative Measurement of Spectrometer Aberrations.

The performance of electron energy loss spectrometers can often be limited by their electron optical aberrations. Due to recent developments in high energy resolution and momentum-resolved electron energy loss spectroscopy (EELS), there is renewed interest in optimizing the performance of such spectrometers. For example, the "ω - q" mode of momentum-resolved EELS, which uses a small convergence angle and requires aligning diffraction spots with the slot aperture, presents a challenge in the realignments of the spectrometer required by the adjustment of the projection lenses. Automated and robust alignment can greatly benefit such a process. The first step toward this goal is automatic and quantitative measurement of spectrometer aberrations. We demonstrate the measurement of geometric aberrations and distortions in EELS within a monochromated scanning transmission electron microscope (STEM). To better understand the results, we present a wave mechanical simulation of the experiment. Using the measured aberration and distortion coefficients as inputs to the simulation, we find a good match between the simulation and experiment, verifying formulae used in the simulation. From verified simulations with known aberration coefficients, we can assess the accuracy of measurements. Understanding the errors and inaccuracies in the procedure can guide further progress in aberration measurement and correction for new spectrometer developments.

Factors influencing outcomes of pelvic osteotomy for residual acetabular dysplasia following closed reduction in patients with developmental dysplasia of the hip.

To investigate the factors influencing outcome of pelvic osteotomy (PO) for residual acetabular dysplasia (RAD) following closed reduction (CR) in patients with developmental dysplasia of the hip (DDH). We retrospectively reviewed 91 patients (95 hips) with DDH who underwent PO for RAD. Tönnis grade, Acetabular index, Center Edge Angle, Reimer's Index (RI), and avascular necrosis of the femoral head (AVN) were assessed. Hips were divided into satisfactory (Severin I/II) and unsatisfactory group (Severin III/IV). Finally, 87 hips (91.5%) had satisfactory and 8 (8.5%) unsatisfactory outcomes. The RI before PO was significantly higher in unsatisfactory (49.6 ± 9%) than in satisfactory group (30.6%±11.8%). All patients without AVN had satisfactory outcome, while it was 78.9% of patients with AVN. Logistic regression analysis showed that higher AVN grade and RI before PO were risk factors for unsatisfactory outcome. Satisfactory outcome was obtained in all hips with RI < 33% before PO, while it was 79.5% if RI > 33% before PO (79.5%). There was no difference in the satisfactory rate between patients undergoing open reduction (66.7%) and those not undergoing (83.3%). The rate of satisfactory outcome in patients undergoing femoral osteotomy (63.6%) was lower than those without it (100%). In patients with RAD following CR, good outcome can be expected after PO alone. AVN and preoperative RI > 33% are risk factors for poor outcome. Additional open reduction and femoral osteotomy do not significantly improve outcome of PO in patients with preoperative RI > 33%.

Transitional ankle fracture management using a new joystick technique.

PURPOSE: To investigate the feasibility and short-term clinical efficacy of the arthrography-assisted joystick technique for the treatment of adolescent transitional ankle fracture. METHODS: A retrospective analysis was performed in 10 adolescent transitional ankle fracture patients treated with the arthrography-assisted joystick technology. There were 7 male patients and 3 female patients with a mean age of 12.80 ± 1.81 years (range: 10-16 years). All cases were closed fractures, and the operation was performed after the failure of manual reduction [X-ray or computed tomography (CT) showed that the fracture gap was > 2 mm]. After the operation, X-ray or CT examination was performed to assess reduction of the fracture. Ankle function and fracture healing were evaluated by assessing the imaging indexes and evaluating the American Orthopedic Foot and Ankle Society (AOFAS) ankle score system. RESULTS: All patients were followed up for an average period of 12.00 ± 3.40 months (range: 8-20 months). The operation time was 40.50 ± 16.90 min (range: 25-80 min), the number of intraoperative fluoroscopy sessions was 18.70 ± 5.91 (range: 10-30 sessions), and the intraoperative blood loss was 5.90 ± 3.38 ml (range: 2-10 ml). X-ray examination showed that all cases achieved bone healing. The fracture healing time was 11.00 ± 2.45 weeks (range: 8-16 weeks). Four cases showed early closure of the epiphysis. The AOFAS scoring system evaluation results of these 10 pediatric cases were excellent. CONCLUSION: The arthrography-assisted joystick technique for the treatment of adolescent transitional ankle fracture offers advantages, such as minimal trauma, simple operation, ideal reduction effect, and the recent curative effect is satisfactory.

Sustained Delivery of Methylsulfonylmethane from Biodegradable Scaffolds Enhances Efficient Bone Regeneration.

Introduction: As a popular dietary supplement containing sulfur compound, methylsulfonylmethane (MSM) has been widely used as an alternative oral medicine to relieve joint pain, reduce inflammation and promote collagen protein synthesis. However, it is rarely used in developing bioactive scaffolds in bone tissue engineering. Methods: Three-dimensional (3D) hydroxyapatite/poly (lactide-co-glycolide) (HA/PLGA) porous scaffolds with different doping levels of MSM were prepared using the phase separation method. MSM loading efficiency, in vitro drug release as well as the biological activity of MSM-loaded scaffolds were investigated by incubating mouse pre-osteoblasts (MC3T3-E1) in the uniform and interconnected porous scaffolds. Results: Sustained release of MSM from the scaffolds was observed, and the total MSM release from 1% and 10% MSM/HA/PLGA scaffolds within 16 days was up to 64.9% and 68.2%, respectively. Cell viability, proliferation, and alkaline phosphatase (ALP) activity were significantly promoted by incorporating 0.1% of MSM in the scaffolds. In vivo bone formation ability was significantly enhanced for 1% MSM/HA/PLGA scaffolds indicated by the repair of rabbit radius defects which might be affected by a stimulated release of MSM by enzyme systems in vivo. Discussion: Finding from this study revealed that the incorporation of MSM would be effective in improving the osteogenesis activity of the HA/PLGA porous scaffolds.

An anatomical classification of congenital proximal radioulnar synostosis based on retrospective MRI measurement combined with radiography.

Existed classifications of congenital proximal radioulnar synostosis (PRUS) mainly focus on osseous changes and do not cover all types of congenital PRUS, ignoring the role and developing status of the supinator. This study aims to explore the correlation between supinator development and radiographic deformity of congenital PRUS. Pediatric patients diagnosed with congenital PRUS in two pediatric Orthopedic centers were evaluated retrospectively. MRI and radiographic images of their bilateral forearms (including normal ones) were collected. The area of supinator, extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), brachioradialis (BRAR) muscle and extensor indicis (EI) muscle were measured on each forearm. The ratios of these muscles were calculated and regarded as an indicator of the developing status of supinator muscle. Twenty-seven congenital PRUS forearms of 16 patients (average 3.45 years) were included. A new MRI & X-ray classification system was proposed to cover all types of radiographic deformity and provide a comprehensive description of supinator development. This study revealed the relation between MRI measured supinator volume and radiographic deformity of congenital PRUS. Supinator muscles were observed in all congenital PRUS cases. A novel classification was proposed, providing a more comprehensive understanding of congenital PRUS.

Variables influencing radiological fracture healing in children with femoral neck fractures treated surgically: A review of 177 cases.

PURPOSE: This study aimed: (1) to determine the probability of and the amount of time needed to achieve fracture healing in children with displaced femoral neck fractures (FNFs) treated surgically; and (2) to determine which factors can affect both the probability of and the amount of time needed to achieve radiological fracture healing in those patients. HYPOTHESIS: Pediatric FNFs require longer time to achieve union than previously reported. METHODS: We retrospectively reviewed the data of 177 children (mean age 10.5±3.9 years) with FNFs treated surgically. Risk factors, including age, sex, laterality, the mechanism of injury, the initial displacement severity, the type of fracture, the time to reduction, the reduction method, the fixation method and the reduction quality, were recorded. Furthermore, the presence of a comminuted medial or posterior cortex on anteroposterior (AP) or lateral radiographs was also recorded. RESULTS: A total of 172 hips (97.2%) achieved radiological fracture healing during the follow-up period. Severe initial displacement, a comminuted cortex on the AP or lateral radiographs and poor reduction quality significantly increased the time needed to achieve radiological fracture healing (p<0.05). Cox regression analysis indicated that the cumulative probability of achieving fracture healing increased linearly during the first 6 months and then plateaued, with a monthly increase of less than 5%. The severity of initial displacement, presence/absence of comminution on the medial or posterior cortex, and reduction quality were factors influencing the probability of achieving fracture healing within the first 6 months after injury (p<0.05). CONCLUSIONS: Radiological union of displaced pediatric FNFs treated surgically increases linearly during the first six month after surgery and then it tends to plateau. Risk factors for nonunion are severe initial displacement, poor reduction quality and the presence of comminuted medial or posterior cortex on AP or lateral radiographs; the same factors are associated with a longer time to achieve fracture healing. LEVEL OF EVIDENCE: III.

Effect of the Number, Size, and Location of Cannulated Screws on the Incidence of Avascular Necrosis of the Femoral Head in Pediatric Femoral Neck Fractures: A Review of 153 Cases.

BACKGROUND: The correlation between the number, size, and location of cannulated screws and the incidence of avascular necrosis (AVN) in children with femoral neck fractures treated surgically is uncertain. METHODS: We retrospectively reviewed 153 children (mean age: 10.6±3.7 y) with femoral neck fractures treated by internal fixation with 2 (n=112) or 3 (n=41) cannulated screws. The severity of initial displacement was divided into incomplete (type I) and complete (type II, angulation <50 degrees; type III, angulation >50 degrees) fractures. The diameter of the screw was measured and recorded as a percentage of the femoral neck width. The distance (D) between the mid-point of each screw at the base (B) of the femoral neck and at the tip (T) of each screw and the superior and anterior cortices of the femoral neck, respectively, were measured on anteroposterior (AP) and lateral (L) radiographs. Values were expressed as the ratio between the measured distance and the width of the femoral neck (BDAP%, TDAP%, BDL%, and TDL%). The correlation between the number, size, and location of the screws and AVN was analyzed. RESULTS: Patients with type II of initial displacement treated with 2 cannulated screws had a lower AVN rate (21.4%) than those treated with 3 screws (44.8%) (P=0.027). Screw diameter (19%) in patients with AVN was larger than (17%) in patients without AVN (P<0.001); patients with AVN had a lower BDAP% (48.6%) than those without AVN (56.4%) (P<0.001). Screw size and BDAP% were risk factors for AVN (P<0.05). Further, screw diameter >16.5% and BDAP% <51.6% of the femoral neck width were the cutoff values for an increased AVN rate (P<0.05). CONCLUSIONS: Patients treated with 2 cannulated screws showed a lower rate of AVN than patients treated with 3 screws. Screws of larger size and screws closer to the piriformis fossa on AP radiographs increased the risk of AVN in children with femoral neck fractures treated surgically. LEVEL OF EVIDENCE: Level III.

A rapid quantitation of cell attachment and spreading based on digital image analysis: Application for cell affinity and compatibility assessment of synthetic polymers.

Accurate and rapid quantitation of cell attachment, spreading, and growth on a polymer thin film coated glass cover slide was developed by analyzing the digital images of cells stained with dyes. A biodegradable block copolymer poly(ethylene glycol)-block-poly(l-lactide-co-2-methyl-2-carboxyl-propylene carbonate) [PEG-b-P(LA-co-MCC)] was synthesized as model polymer with poly(L-lactic acid) [PLLA] as a control polymer. Only a small quantity of polymer (~5 mg) was needed in this method through dissolving in a solvent and casting on cover slides which were previously modified with dimethyl dichlorosilane (DMDC). Then it was seeded with cells and taken pictures with a digital camera under an optical microscope and analyzed with ImageJ software. Cell number and a series of morphological data were obtained, including cell area, circularity, perimeter and Feret's diameter, etc. The quantitative analysis results indicated that cells preferred to attach and spread on the surface of the copolymer PEG-b-P(LA-co-MCC) compared to PLLA during 24 h of cell culture. This efficient procedure provides a series of convincing statistical data to evaluate the direct interaction between cells and polymers with only an optical microscope, a digital camera and ImageJ software. It's a rapid, economic way for assessing cell affinity and compatibility of novel synthetic polymers by cell culture in vitro.

The Prognostic Value of Leucine-Rich α2 Glycoprotein 1 in Pediatric Spinal Cord Injury.

OBJECTIVE: Leucine-rich α2 glycoprotein 1 (LRG1) is a novel cytokine, which is believed to be involved in the inflammatory process of a series of diseases. However, the relationship between LRG1 and spinal cord injury (SCI) has not been reported. The purpose of our study is to determine the predictive value of LRG1 for the prognosis of pediatric SCI (PSCI). METHODS: This study recruited 64 patients with confirmed PSCI and 40 healthy controls at Foshan Traditional Chinese Medicine Hospital from January 2016 to December 2020. The clinical information of all participants at the time of admission was recorded. Peripheral blood was collected, and commercial reagents were used to detect the level of serum LRG1. At the same time, the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) was used to assess the severity of PSCI. RESULTS: All participants were divided into PSCI group (n = 64) and NC group (n = 40). There was no significant difference in clinical information (age, gender, heart rate, systolic blood pressure, diastolic blood pressure, sampling time from injury, white blood cells, and C-reactive protein) between the two groups (p > 0.05). According to the interquartile range of serum LRG1, we compared the motor and sensory scores of ISNCSCI and found that serum LRG1 levels were negatively correlated with the prognosis of PSCI patients (p < 0.001). The results of receiver operating curve (ROC) showed that the sensitivity, specificity, and AUC (Area Under the Curve) of serum LRG1 level in predicting the prognosis of PSCI were 68.4%, 69.1%, and 0.705, respectively. The cut-off value of serum LRG1 level predicting the prognosis of PSCI is 21.1 µg/ml. CONCLUSIONS: Serum LRG1 level is significantly increased in PSCI patients, and the elevated LRG1 level is negatively correlated with the prognosis of PSCI patients. Serum LRG1 may be a potentially useful biomarker for predicting PSCI.

Biomechanical analysis for five fixation techniques of Pauwels-III fracture by finite element modeling.

BACKGROUND AND OBJECTIVES: There are many fixation methods for Pauwels- III fracture, the most common implants are Locking Plate (LP), Dynamic Hip Screw (DHS), Multiple Lag Screw (MLS), and mixed fixture (DHS+MLS) implants, the common procedure is HemiArthroplasty (HA). However, how these fixtures biomechanically function is not clear. The aims of this study are to compare the mechanical behaviors of these five implants by finite element modeling and determinate the most suitable procedure for individuals with Pauwels- III fractures. METHODS: We gathered 20 sets of femur images from CT scans in the *.dicom format first, and then processed them by using reverse engineering software programs, such as Mimics, Geomagic Studio, UG-8, Pro-Engineer and HyperMesh. Finally, we assembled and analyzed the five types of fixture models, the LP, DHS, MLS, DHS+LS and HA models, by AnSys. RESULTS: These numerical models of Pauwels III fractures, including fixators and a simulative HA, were validated by a previous study and a cadaver test. Our analytical findings include the following: the displacements of all fixtures were between 0.3801 and 1.0834 mm, and the differences were not statistically significantly different; the resulting average peaks in stress were e(Ha) = 43.859 ≤ d(LP) = 60.435 ≤ b(MLS) = 68.678 < c(LS+DHS) = 98.478 < a(DHS) = 248.595 in Mpa, indicating that the stress of DHS and DHS+LS are greater than those of LP, HA and MLS, while the last 3 models were not significantly different. CONCLUSIONS: To optimize the treatment for Pauwels III factures clinically, HA and LP should be proposed.

Variables influencing the pelvic radiological evaluation in children with developmental dysplasia of the hip managed by closed reduction: a multicentre investigation.

PURPOSE: This study aims to evaluate (1) the probability to achieve normal pelvic radiographs in children with developmental dysplasia of the hip (DDH) treated by closed reduction and (2) the amount of time needed to achieve normal pelvic radiographs and to assess what factors influence both probability and time to achieve normal radiographic parameters following CR and spica cast immobilization for DDH. METHODS: We retrospectively reviewed 436 patients (393 girls, 43 boys; 507 hips) with DDH treated by closed reduction (CR). Tönnis grade, AVN, acetabular index (AI), centre-edge angle (CEA), and Severin radiographic grade were evaluated on plain radiographs. Criteria to rate pelvis radiographs as normal were established. Cox regression was used to evaluate the factors influencing the probability and the time to achieve normal radiographs. RESULTS: According to our criteria, 167 hips (32.9%) achieved normal radiographic parameters during follow-up. The overall amount of time to achieve normal pelvis radiographs was 36.1 ± 15.5 months. Patients older than 24 months of age at the time of CR needed longer time to achieve normal radiographic parameters (55.2 ± 28 months) compared with other age groups. Cox regression analysis suggested the overall cumulative probability of recovery increased by 46% at five years following CR, then it tended to plateau with an annual increase less than 5%. Age older than 24 months, bilateral dislocation, pre-operative AI greater than 40°, and AVN were risk factors for reduced probability of achieving normal radiographic parameters. CONCLUSIONS: The cumulative probability of achieving normal pelvis radiographs increases linearly during the first five years following CR, then it tends to plateau. Age older than 24 months and Tönnis grade III and IV are associated with longer time to achieve normal radiographic parameters. Age older than 24 months, bilateral dislocation, pre-operative AI greater than 40°, and AVN are risk factors for reduced probability of achieving normal radiographic parameters in children with DDH treated by closed means.

Initial displacement as a risk factor for avascular necrosis of the femoral head in pediatric femoral neck fractures: a review of one hundred eight cases.

PURPOSE: To evaluate the correlation between avascular necrosis (AVN) and the amount (severity) and direction (translation and angulation) of initial displacement of pediatric femoral neck fractures. METHODS: We retrospectively reviewed 108 pediatric patients (mean age 10.3 ± 4.1 years) with femoral neck fractures. The amount of initial translation (T) and angulation (A) was measured on anteroposterior (AP; TAP% and AAP) and lateral (TL% and AL) radiographs. The direction of translation was determined on AP (medial or lateral) and lateral radiographs (anterior or posterior). Furthermore, the presence of a comminuted medial cortex on the AP pelvis radiograph was also recorded. Logistic regression analysis, receiver operating characteristic (ROC) curve analysis, student's t tests, and chi-square tests were used to evaluate the correlation between AVN and the severity and direction of displacement. RESULTS: Twenty-eight out of 108 hips (25.9%) developed AVN of the femoral head. Logistical regression analysis indicated that TAP%, TL%, AAP, and AL were risk factors for AVN (P < 0.05). The analysis of ROC curves found that TAP% over 37.4% and TL% over 29% were the cut-off values for an increased incidence of AVN; similarly, AAP over 8° and AL over 18.6° were the cut-off values for an increased incidence of AVN. The amount of initial translation is a better predictor of AVN than angulation is; fractures with posterior translation (P = 0.002) and/or medial comminution had a significantly higher incidence of AVN (P = 0.005). The mean diagnostic accuracy of translation (74-75%) was significantly higher than that of angulation (65-66%). CONCLUSIONS: Displacement severity and direction are important radiological parameters to be assessed in children with femoral neck fractures. Initial translation better predicts AVN than angulation does. Posterior translation and medial comminution are associated with an increased risk of AVN.

Free Fracture Fragment Predicts Poorer Outcomes in Adolescents With Delbet II Femoral Neck Fracture.

BACKGROUND: This retrospective multicenter study investigated whether the presence of free fracture fragments is associated with the clinical outcome of adolescents with Delbet II femoral neck fracture (FNF). MATERIALS AND METHODS: The study population comprised 74 adolescents with Delbet II FNF, with an average age of 13.31 y (range, 10-17 y). There were 19 and 55 patients, respectively, with and without (control) free fracture fragments. The patients underwent open (n = 41) or closed (n = 33) fracture reduction and then cannulated screw internal fixation. Postoperative functional evaluation was performed using Ratliff's criteria, and complications such as femoral head necrosis, premature epiphyseal closure, and coxa vara were recorded. RESULTS: All patients achieved bony union during the mean follow-up period of 15.6 mo (range, 12-78 mo). By Ratliff's criteria, the clinical outcomes of the patients with free fracture fragment (three excellent, eight good, eight poor) were significantly worse compared with the control group (26 excellent, 20 good, and nine poor). The rate of complications (femoral head necrosis, premature epiphyseal closure, and coxa vara) of patients with free fracture fragments was significantly higher than that of the control patients. CONCLUSIONS: In adolescents with Delbet II FNF, the presence of free fracture fragments is associated with poorer clinical outcomes. Delbet II FNF in adolescents with free fracture fragment may be a special clinical entity with a poorer outcome.

Risk factors for the development of avascular necrosis after femoral neck fractures in children: a review of 239 cases.

AIMS: The aim of this study was to clarify the factors that predict the development of avascular necrosis (AVN) of the femoral head in children with a fracture of the femoral neck. PATIENTS AND METHODS: We retrospectively reviewed 239 children with a mean age of 10.0 years (sd 3.9) who underwent surgical treatment for a femoral neck fracture. Risk factors were recorded, including age, sex, laterality, mechanism of injury, initial displacement, the type of fracture, the time to reduction, and the method and quality of reduction. AVN of the femoral head was assessed on radiographs. Logistic regression analysis was used to evaluate the independent risk factors for AVN. Chi-squared tests and Student's t-tests were used for subgroup analyses to determine the risk factors for AVN. RESULTS: We found that age (p = 0.006) and initial displacement (p = 0.001) were significant independent risk factors. Receiver operating characteristic (ROC) curve analysis indicated that 12 years of age was the cut-off for increasing the rate of AVN. Severe initial displacement (p = 0.021) and poor quality of reduction (p = 0.022) significantly increased the rate of AVN in patients aged 12 years or greater, while in those aged less than 12 years, the rate of AVN significantly increased only with initial displacement (p = 0.048). A poor reduction significantly increased the rate of AVN in patients treated by closed reduction (p = 0.026); screw and plate fixation was preferable to cannulated screw or Kirschner wire (K-wire) fixation for decreasing the rate of AVN in patients treated by open reduction (p = 0.034). CONCLUSION: The rate of AVN increases with age, especially in patients aged 12 years or greater, and with the severity of displacement. In patients treated by closed reduction, anatomical reduction helps to decrease the rate of AVN, while in those treated by open reduction, screw and plate fixation was preferable to fixation using cannulated screws or K-wires. Cite this article: Bone Joint J 2019;101-B:1160-1167.

Radiographic outcome of children older than twenty-four months with developmental dysplasia of the hip treated by closed reduction and spica cast immobilization in human position: a review of fifty-one hips.

PURPOSE: This study aimed to investigate the radiographic outcomes, rate of redislocation, and avascular necrosis of proximal femoral epiphysis (AVN) in patients aged 24 to 36 months with developmental dysplasia of the hip (DDH) treated by closed reduction (CR) and spica cast immobilization in human position. MATERIAL AND METHODS: We reviewed the medical records of 39 patients (51 hips) aged 24 to 36 months with DDH treated by CR and spica cast immobilization in human position. The Tönnis grade, rate of redislocation and AVN, acetabular index (AI), centre-edge angle (CEA), and Severin radiographic grade were evaluated on plain radiographs. RESULTS: Among the included 39 patients (51 hips), 15 hips (29.4%) were Tönnis grade II, 24 hips (47.1%) were grade III, and 12 hips (23.5%) were grade IV. In 47 hips (92.2%), the ossific nucleus was present at the time of CR. Stable reduction was achieved by CR in 39/51 hips (76.5%) and redislocation occurred in 12/51 hips (23.5%). Among the 12 hips that redislocated, 11 underwent open reduction and one repeated CR. Two out of 40 hips (5%) treated by CR developed AVN. Overall, 54.6% of the hips had satisfactory outcomes (39.2% Severin type I and 17.6% type II), while 45.4% had unsatisfactory outcomes (39.2% Severin type III and 3.9% type IV). Of the 40 hips treated by CR, 57.5% and 42.5% of cases had satisfactory outcomes and residual acetabular dysplasia, respectively. Six out of 11 hips (54.6%) treated by open reduction and pelvic osteotomy had satisfactory outcomes. CONCLUSIONS: Our study showed that stable CR could be achieved in 76.5% of patients aged 24 to 36 months with DDH at the time of index procedure. Satisfactory outcomes can be expected in 56.4% of the cases (5.0% AVN rate), although late acetabular dysplasia may develop in 43.6% of the hips.

Traction does not decrease failure of reduction and femoral head avascular necrosis in patients aged 6-24 months with developmental dysplasia of the hip treated by closed reduction: a review of 385 patients and meta-analysis.

This study aimed to investigate the effects of preliminary traction on the rate of failure of reduction and the incidence of femoral head avascular necrosis (AVN) in patients with late-detected developmental dysplasia of the hip treated by closed reduction. A total of 385 patients (440 hips) treated by closed reduction satisfied the inclusion criteria. Patients were divided in two groups according to treatment modality: a traction group (276 patients) and a no-traction group (109 patients). Tönnis grade, rate of failure reduction, AVN rate, acetabular index, center-edge angle of Wiberg, and Severin's radiographic grade were assessed on plain radiographs, and the results were compared between the two groups of patients. In addition, a meta-analysis was performed based on the existing comparative studies to further evaluate the effect of traction on the incidence of AVN. Tönnis grade in the traction group was significantly higher than in the no-traction group (P = 0.021). The overall rate of failure reduction was 8.2%; no significant difference was found between the traction (9.2%) and no-traction groups (5.6%) (P = 0.203). The rates of failure reduction were similar in all Tönnis grades, regardless of treatment modality (P > 0.05). The rate of AVN in the traction group (14%) was similar to that of the no-traction group (14.5%; P = 0.881). Moreover, the rates of AVN were similar in all Tönnis grades, regardless of treatment modality (P > 0.05). The meta-analysis did not identify any significant difference in the AVN rate whether preliminary traction was used or not (odds ratio = 0.76, P = 0.32). At the last follow-up visit, the two groups of patients had comparable acetabular indices, center-edge angles, and Severin's radiographic grades (P > 0.05). In conclusion, preliminary traction does not decrease the failure of reduction and the incidence of AVN in developmental dysplasia of the hip treated by closed reduction between 6 and 24 months of age.

Efficient and stable emission of warm-white light from lead-free halide double perovskites.

Lighting accounts for one-fifth of global electricity consumption1. Single materials with efficient and stable white-light emission are ideal for lighting applications, but photon emission covering the entire visible spectrum is difficult to achieve using a single material. Metal halide perovskites have outstanding emission properties2,3; however, the best-performing materials of this type contain lead and have unsatisfactory stability. Here we report a lead-free double perovskite that exhibits efficient and stable white-light emission via self-trapped excitons that originate from the Jahn-Teller distortion of the AgCl6 octahedron in the excited state. By alloying sodium cations into Cs2AgInCl6, we break the dark transition (the inversion-symmetry-induced parity-forbidden transition) by manipulating the parity of the wavefunction of the self-trapped exciton and reduce the electronic dimensionality of the semiconductor4. This leads to an increase in photoluminescence efficiency by three orders of magnitude compared to pure Cs2AgInCl6. The optimally alloyed Cs2(Ag0.60Na0.40)InCl6 with 0.04 per cent bismuth doping emits warm-white light with 86 ± 5 per cent quantum efficiency and works for over 1,000 hours. We anticipate that these results will stimulate research on single-emitter-based white-light-emitting phosphors and diodes for next-generation lighting and display technologies.

Three-beam convergent-beam electron diffraction for measuring crystallographic phases.

Under almost all circumstances, electron diffraction patterns contain information about the phases of structure factors, a consequence of the short wavelength of an electron and its strong Coulombic interaction with matter. However, extracting this information remains a challenge and no generic method exists. In this work, a set of simple analytical expressions is derived for the intensity distribution in convergent-beam electron diffraction (CBED) patterns recorded under three-beam conditions. It is shown that these expressions can be used to identify features in three-beam CBED patterns from which three-phase invariants can be extracted directly, without any iterative refinement processes. The octant, in which the three-phase invariant lies, can be determined simply by inspection of the indexed CBED patterns (i.e. the uncertainty of the phase measurement is ±22.5°). This approach is demonstrated with the experimental measurement of three-phase invariants in two simple test cases: centrosymmetric Si and non-centrosymmetric GaAs. This method may complement existing structure determination methods by providing direct measurements of three-phase invariants to replace 'guessed' invariants in ab initio phasing methods and hence provide more stringent constraints to the structure solution.