Developmental dysplasia of the hip (DDH) is the most common hip abnormality in children. Closed or open reduction and cast immobilization are the most commonly used treatments for patients aged 6 to ...18 months with dislocation; they are also used in children younger than 6 months when brace treatment is not effective. During cast immobilization, surgeons need reliable and timely imaging methods to assess the status of hip reduction to ensure successful treatment and avoid complications. Several methods are used, but they have disadvantages. We developed and, in this study, evaluated a hip medial ultrasound method to evaluate the status of hip reduction in children treated with a spica cast.
Is hip medial ultrasound more accurate than radiography for determining the status of hip reduction in children treated with a spica cast?
Between November 2017 and December 2020, we treated 136 patients with closed or open reduction and spica casting for DDH in our department. These children were 3 to 18 months old at the time of surgical reduction and had a specific medical history, physical examination findings, or AP radiographic evidence of unilateral or bilateral DDH. None had a concomitant femoral/acetabular osteotomy procedure in these hips. All patients underwent hip medial ultrasound, AP radiography, and MRI under sedation within 2 to 7 days after open or closed reduction. The examination time was from the second day after reduction to enable the patient to recover from anesthesia. MRI was performed within 7 days after reduction because of a few long appointment times, and ultrasound and AP radiography were always performed 1 or 2 days before MRI. Based on that, 65% (88 of 136 88 hips) of patients were excluded due to the absence of MRI, ultrasound, or AP radiography; 3% (4 of 136 4 hips) of patients were excluded because of concurrent congenital spina bifida, Larson syndrome, or Prader-Willi syndrome; and 1% (1 of 136 1 hip) of patients were excluded because the patient underwent MRI before ultrasound. A total of 32% (43 of 136 43 hips) of patients were eligible for analysis in this cross-sectional diagnostic study, and these 43 patients underwent AP radiography, ultrasound, and MRI. In this retrospective study, the mean age at the time of surgery was 10 ± 4 months (male:female ratio 5:38; unilateral DDH: 34; bilateral DDH: 9). To ensure the independence of the results, the study was limited to one hip per patient (in patients with bilateral DDH, the right hip was evaluated). The reduction of 43 hips (left:right ratio 26:17; closed:open reduction ratio 30:13) was evaluated by MRI, hip medial ultrasound, and radiography. Children with spica casts were placed in the supine position, which is necessary to expose the perineum for ultrasound. We used a broad-spectrum, microconvex, and intracavitary probe. The acetabular medial wall was identified by the triradiate cartilage of the ischial tuberosity and the pubis superior, and the femoral head was identified by the femoral neck. Then, the acetabulum coronal midsectional plane was used to determine the positions of the femoral head and acetabulum and to measure the triradiate cartilage-femoral distance. MRI examinations were performed using a 1.5-T MRI system with an eight-channel body coil. Each reviewer evaluated each reduction independently. Additionally, to further assess the hip medial ultrasound method's reliability and reproducibility, we investigated the interobserver and intraobserver agreement in evaluating the reduction using hip medial ultrasound. Using ultrasound or radiography, the reviewers classified hips as reduced, uncertain status, or dislocated. MRI was considered the gold standard for assessing hip reduction, and the reviewers classified hips as reduced or dislocated by MRI. Patients with hips with an uncertain reduction status according to ultrasound or radiography were retained in the analysis. Thus, the test results of radiography and ultrasound were classified into three classifications (positive, negative, or uncertain) in the present study. The test was considered positive or negative when patients were assessed with dislocation or without dislocation, respectively. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ultrasound and radiography were calculated and compared. We combined uncertain and positive into the positive classification to be conservative in the statistical choices. The specificity, sensitivity, PPV, and NPV were analyzed based on this premise. Furthermore, a subgroup analysis was conducted by sex. MRI evaluation revealed that 41 hips were reduced and two hips were dislocated.
The sensitivity, specificity, PPV, and NPV of ultrasound were 100% (95% CI 16% to 100%), 95% (95% CI 84% to 99%), 50% (95% CI 7% to 93%), and 100% (95% CI 91% to 100%), respectively. The sensitivity, specificity, PPV, and NPV of radiography were 50% (95% CI 1% to 99%), 68% (95% CI 52% to 82%), 7% (95% CI 0% to 34%), and 97% (95% CI 82% to 100%), respectively. Ultrasound showed a higher specificity (95% versus 68%; p < 0.001) and PPV (50% versus 7%; p = 0.02) than radiography. The sensitivity, specificity, PPV, and NPV of ultrasound were 100% (95% CI 16% to 100%), 94% (95% CI 81% to 99%), 50% (95% CI 7% to 93%), and 100% (95% CI 90% to 100%), respectively, for female patients (with only five male patients, we could not perform these analyses in this group). The sensitivity, specificity, PPV, and NPV of radiography were 50% (95% CI 1% to 99%), 64% (95% CI 46% to 79%), 7% (95% CI 0% to 34%), and 96% (95% CI 79% to 100%), respectively, for female patients. The κ values for intra- and interobserver reliability both were 1.0.
Hip medial ultrasound can directly visualize the femoral head and acetabulum. Hip medial ultrasound is more reliable than radiography as a preliminary evaluation method and does not involve irradiation. We recommend using hip medial ultrasound during outpatient follow-up visits for patients younger than 2 years treated with hip reduction and cast immobilization.
Level III, diagnostic study.
By introducing constituent phases with high stacking fault energy (SFE), we have investigated the dissociation mechanisms of misfit dislocations existing in several semi-coherent interfaces using ...atomistic simulations and interface dislocation theory. Under large misfit dislocation spacing induced by huge lattice mismatch, misfit dislocation will dissociate independently with little influence of SFE. Meanwhile, the formation of a twin structure via dislocation climbing and the generation of Kink structure is found. When the dislocation spacing is sufficiently small, the supposed dissociated defect structure based on the geometric analysis becomes energetically unfavorable due to the high SFE, and distinct dissociation processes of the misfit dislocations occur: the dissociation of the dislocations at certain nucleate sites is hindered; the misfit dislocation decomposes towards bilateral phases rather than to only one of the constitute phase; the dissociation direction is reversed. Our work presents a novel understanding on the plastic-deformation mechanisms of semi-coherent interfaces and provides several feasible solutions to tune defect structures for material strengthening by introducing constitute phases with high SFE, controlling misfit parameters and applying different loading schemes.
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•Small dislocation spacing brings intense interaction between adjacent dislocations and may vary the dissociation mechanisms.•The formation of a twin crystal structure generated via dislocation climbing and generation of Kink structure is found.•Under small misfit dislocation spacing, distinct dissociation processes occur to reduce system energy.•The dissociation can be hindered or/and the dissociation direction can be changed.
Mg single crystals were compressed along 0 0 0 1 at room temperature to various stress levels (40, 80, 120, 160 and 320 MPa) and the evolution of dislocation structure with stress increment was ...investigated by TEM. 〈c+a〉 slip is confirmed to be the dominant deformation mode; the predominance of edge dislocation debris lying along the
implies that screw 〈c+a〉 dislocations are more mobile than their edge counterpart. The 〈c+a〉 edge dislocation may dissociate into 〈c〉 and 〈a〉 dislocations, and the latter can extend further on the basal plane and bound a basal-stacking fault. Numerous 〈c+a〉-type dislocation loops are generated during deformation and together with point defects and edge dipoles, contribute to the observed high work hardening rate. The smaller (<100 nm in diameter) dislocation loops are perfect 〈c+a〉 dislocation loops but the larger loops dissociate into two concentric 1/6
-type partial dislocations enclosing a basal-stacking fault. Since the Burgers vector of these perfect and faulted loops is out of the loop plane, these loops are sessile, change size by climb, and act as obstacles to mobile dislocations.
Galeazzi fracture dislocation is a compound injury that encompasses fractures of the distal third of the radius and dislocation of the distal radial ulnar joint (DRUJ). Clinically, this condition is ...rare and often leads to distal ulnar bifurcation. In previous similar reports, patients were effectively managed through surgery.
In this case report, we describe an 11-year-old male child who presented with an ulnar bifida following trauma to the hand, and was treated with manipulation and conservative treatment without surgery. A follow-up performed over the years demonstrated that the patient recovered well, and had normal wrist movements without significant pain, and the patient expressed great satisfaction.
Ulnar diaphyseal fracture may occur in children or adolescents due to injuries, and may be accompanied with manipulation and repositioning. Conservative treatment can be applied to avoid the trauma associated with surgery especially in the absence of severe joint mobility impairment with good outcomes.
The elbow is the joint that most usually dislocates in children. In contrast to the widely known recent increase in the incidence of upper-extremity fractures and their operative treatment in ...children, potential trends in elbow dislocation are not clear. In this study we aimed to clarify the recent epidemiology of childhood elbow dislocation, in particular the potential change in incidence and treatment.
A population-based study was performed to evaluate the annual incidence and the characteristics of injury, patients and treatment. All children < 16 years of age with an elbow dislocation in 1996-2014 in the Oulu University Hospital District, Finland, were included. Elbow dislocations with and without an associated fracture were included. The mean number of children in the population at risk was 85,600, according Statistics Finland.
There were 104 patients with a mean age of 11.3 years (SD 2.6). The annual incidence was 6.4 (mean) per 100,000 children in 1996-2014 and no changing trend in incidence during the study period was found. Trampoline jumping was the most usual reason for the dislocations (N = 15, 14.4%). The majority (N = 73/104, 70.2%) were treated non-operatively by reduction and casting. There was no change in surgical treatment during the study time.
In contrast to increasing incidence of upper-extremity fractures in children, there has not been a change in the incidence of elbow dislocation in children. There was no change in surgical treatment in 1996-2014.
•The LED layers is deposited on cone-patterned sapphire substrates.•Threading dislocations and V-defects are investigated by TEM and DCXRD.•The TDs’ propagations mechanism are analyzed on UPSS and ...CPSS.•Temperature dependence of defects level are considered.
Transmission electron microscope (TEM) and double-crystal X-ray diffraction (DCXRD) measurements have been performed to investigate dislocations of the whole structure of the LED layers deposited on both the conventional (unpatterned sapphire substrate, UPSS) and patterned sapphire substrates (PSS). TEM results show that there exists a dislocation-accumulated region near the substrate/GaN interface, where the dislocation density is much higher with the UPPS than that with the PSS. It indicates that the pattern on the substrate surface is able to block the formation and propagation of dislocations. Further analysis discloses that slope of the pattern is found to suppress the deposition of GaN, and thus to provide more spaces for the epitaxially lateral overgrowth (ELO) of high temperature GaN, which significantly reduces the number of the initial islands, and minimizes dislocation formation due to the island coalescence. V-defect incorporating the threading dislocation is detected in the InGaN/GaN multi-quantum wells (MQWs), and its propagation mechanism is determined as the decrease of the surface energy due to the incorporation of indium. In addition, temperature dependence of dislocation formation is further investigated. The results show that dislocation with the screw component decreases monotonously as temperature goes up. However, edge dislocation firstly drops, and then increases by temperature due to the enhanced thermal mismatch stress. It implies that an optimized range of the growth temperature can be obtained to improve quality of the LED layers.
InAs quantum dots (QDs) are receiving attention as next‐generation E‐band light source that offers high‐temperature operation and temperature insensitive operation. However, high‐density crystal ...defects occur at the interface between the InGaAs buffer layer and GaAs, resulting in reduced device performance and shortened lifetime. Here, E‐band QD lasers are demonstrated on InGaAs buffer layer, which suppressed the spread of dislocation by introducing a high‐temperature annealing and a strained layer superlattice filter. In the device, the peak wavelength at room temperature is measured to be 1427 nm and the threshold current density was 440 A/cm2. This result indicates that E‐band QD laser structures on low threading dislocation density are promising for the realisation of high‐performance E‐band lasers.
Abstract
BACKGROUND
Conventional 2-dimensional (2-D) definition of atlantoaxial dislocation (AAD) is inadequate for coexisting 3-D displacements.
OBJECTIVE
To prospectively classify AAD and its ...related abnormalities along 3 Cartesian coordinates and assess their association with torticollis.
METHODS
One hundred and fifty-four patients with congenital AAD were prospectively classified according to their C1-2 displacement along 3 Cartesian coordinates utilizing 3-D multiplanar CT. The impact of this 3-D dislocation on occurrence of clinically manifest torticollis was also evaluated and surgical treatment was planned.
RESULTS
Three dimensional CT assessment detected the following types of C1-2 dislocations: I:translational dislocation (along Z coordinate, n = 37 24%); II: central dislocation (along Y coordinate, n = 10 6.5%); III: translational+central dislocation (along Z+Y coordinates, n = 42 27.3%); IV: translational dislocation+ rotational dislocation+coronal tilt (along Z+X coordinates, (n = 6 3.9%); V: central dislocation (basilar invagination)+rotational dislocation+coronal tilt (along Y+X coordinates, n = 11 7.1%); VI: translational dislocation+ central dislocation+ rotational dislocation+ coronal tilt (along all 3 axes, n = 48 31%). Assessing degree of relative C1-2 rotation revealed that 27 (37%) of 85 patients with <50 rotation and 54 (78%) of 69 patients with >5° rotation had associated torticollis. Translational dislocation had negative association (odds ratio OR 0.1, 95% confidence interval CI; 0.47-0.32, P = .00), while type VI (OR 5.0, 95% CI 2.2-11.19, P = .00), type V (OR 4.44, 95% CI 0.93-21.26, P = .04), and type IV (OR 1.84, 95% CI 0.32-10.38, P = .48) dislocations had strong positive association with torticollis. Sixty-two (40%) patients improved, 68 (44%) remained unchanged, and 24 (16%) patients worsened postoperatively. Twenty-eight patients required second-stage transoral decompression following posterior distraction–fusion due to neurological nonimprovement.
CONCLUSION
Three-dimensional assessment of AAD including evaluation of culpable C1-2 facet joints addresses anomalous displacements in 3 Cartesian planes. This provides targets for adequate cervicomedullary decompression-stabilization, and helps in the management of accompanying torticollis.
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