The Clinical Significance of Infolded Limbus on Postreduction Arthrogram in Developmental Dysplasia of the Hip.

BACKGROUND: The purpose of this study was to investigate whether presence of an infolded limbus on hip arthrogram at index closed reduction was associated with increased residual dysplasia or secondary surgery. METHODS: We retrospectively reviewed all patients who underwent closed reduction for dysplasia of the hip with a minimum 2-year follow-up between 1980 and 2016. Demographic data was obtained including the age at reduction and severity of dislocation based on the International Hip Dysplasia Institute (IHDI) classification. Arthrograms performed at time of closed reduction were separately reviewed by 3 fellowship-trained pediatric orthopaedic surgeons to evaluate for an infolded limbus. The primary radiographic outcome was acetabular indices at 2 and 4 years postreduction. We also assessed the presence of avascular necrosis and rate of secondary reconstructive surgery for residual dysplasia. RESULTS: A total of 182 hips in 165 patients underwent closed reduction at a mean age of 9.8±4.5 mo and were followed a mean of 9.0±4.9 y. An infolded limbus was identified in 20.3% (37/182) hips with substantial agreement among the 3 graders (Fleiss κ=0.75). The frequency of labral infolding increased with the severity of dislocation (8.8%% of IHDI II, 26.7% IHDI III, and 25.0% of IHDI IV hips; P=0.03). Hips with infolded limbus were older at reduction (12.4±5.3 vs. 9.2±5.8 mo, P=0.001). The mean acetabular index was higher in hips with infolded limbus than hips without at 2 years postreduction (34.8±4.8 vs. 32.6±5.8 degrees, respectively; P=0.04). However, multivariate analysis revealed that only the severity of dislocation predicted dysplasia at 2 years postreduction. No significant difference in acetabular index was seen at 4 years postreduction (27.2±7.4 vs. 25.4±6.5 degrees, P=0.24). There was no difference in avascular necrosis between groups (P=0.74). There was no difference in rate of secondary surgery between hips with labral infolding and those without (35% vs. 30%, respectively; P=0.52). CONCLUSIONS: An infolded limbus was more common in older patients with more severe dislocations. However, it is not associated with increased residual dysplasia or secondary surgery and may have limited utility in decision-making during closed reduction. LEVEL OF EVIDENCE: Level II-prognostic study.

Outpatient Bryant's Overhead Traction Does Not Affect the Rate of Open Reduction or Avascular Necrosis in Developmental Dislocation of the Hip.

BACKGROUND: The efficacy of preliminary traction to increase the likelihood of closed reduction and/or decrease the incidence of avascular necrosis in the management of developmental dysplasia of the hip (DDH) is controversial. We sought to document compliance with and effectiveness of Bryant's outpatient traction in patients with idiopathic DDH. METHODS: Patients presenting between 6 and 24 months of age with idiopathic irreducible DDH were prospectively enrolled in the study. Prereduction outpatient traction was prescribed at participating surgeons' preference and parents' expressed willingness to comply with a traction protocol of at least 14 hours/day for 4 weeks. Traction hours were documented using a validated monitor; parents also reported average daily usage. Rate of successful closed reduction and evidence of capital epiphyseal growth disturbance 1 year' and 2 years' postreduction were documented. RESULTS: Ninety-six patients with 115 affected hips were enrolled. Reliable recorded traction hours were obtained in 31 patients with 36 affected hips. Defining compliance as 14 hours/day average use, 14 of 31 patients (45.2%) were compliant, 2 (6.5%) admitted noncompliance, while 15 (48.2%) claimed to be compliant, but were not. Overall, 68/115 hips (59.0%) were closed reduced. Age at treatment was the only demographic characteristic associated with an increased incidence of closed reduction (11.7 vs. 14.6 mo, P<0.01). Successful closed reduction was achieved in 10/16 hips (62.5%) of compliant patients, 12/20 (60.0%) of noncompliant patients, and 43/72 (59.7%) of no-traction patients. Irregular ossific nucleus development was noted 1-year postindex reduction in 5/16 (31.3%) of complaint-patient hips and 25/92 (27.2%) of noncomplaint and no-traction hips. Distorted proximal femoral epiphysis was noted at 2 years postreduction in 2/15 hips (13.3%) of compliant patients and 15/52 hips (28.8%) in noncompliant and no-traction patients. None of these differences was statistically significant. CONCLUSIONS: Parent-reported use of outpatient traction is unreliable. Four weeks of outpatient overhead Bryant's traction did not affect the rate of closed reduction or avascular necrosis in late-presenting DDH in this cohort. LEVEL OF EVIDENCE: Level II-prospective cohort.

Secondary Surgery and Residual Dysplasia Following Late Closed or Open Reduction of Developmental Dysplasia of the Hip.

BACKGROUND: Outcomes studies following successful closed reduction of late-detected developmental dysplasia of the hip (DDH) reveal high rates of secondary reconstructive surgery with limited comparative data demonstrating lower rates of residual dysplasia with open reduction. The purpose of this study was to compare long-term outcomes, with regard to radiographic evidence of residual dysplasia and secondary reconstructive procedures, between late closed and late open reduction for DDH in patients 6 to 24 months of age at reduction. METHODS: We identified all patients between 6 and 24 months of age who underwent closed or open reduction for DDH between 1980 and 2008 and were followed until at least 10 years of age. Outcomes included radiographic measurement of acetabular dysplasia after triradiate cartilage closure, development of osteonecrosis, and the need for secondary procedures for residual dysplasia. RESULTS: One hundred and four hips underwent index closed reduction and 54 hips underwent index open reduction. There was no significant difference in the age at reduction (p = 0.07). Among the 116 hips for which initial anteroposterior pelvic radiographs were available, most closed reductions (55%) were performed in International Hip Dysplasia Institute (IHDI) grade-III hips whereas most open reductions (71%) were performed in IHDI grade-IV hips. Analysis of the hips that did not undergo a secondary procedure showed that those with an index open reduction had a greater lateral center-edge angle (mean and standard deviation, 27.2° ± 10.0° versus 22.4° ± 6.8° in the closed reduction cohort; p = 0.02), lower femoral head extrusion index (22.2% ± 8.9% versus 26.0% ± 6.2%; p = 0.04), and lower Sharp angle (43.3° ± 6.0° versus 46.6° ± 3.1°; p = 0.002) at triradiate closure. There was no difference in the prevalence of osteonecrosis (Bucholz-Ogden grades II, III, and IV) between the closed and open reduction cohorts (22% versus 19%, respectively; p = 0.60). Secondary procedures were performed more frequently after closed reduction than after open reduction (47% versus 30%, respectively; p = 0.03). CONCLUSIONS: In patients with late reduction of DDH, closed reduction was associated with increased residual dysplasia and it was associated with a higher rate of secondary surgery in those >12 months old despite a decreased severity of displacement based on the IHDI classification. Additional, prospective studies with assessment of functional outcomes are needed to validate these findings. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Near-room-temperature mid-infrared quantum well photodetector.

We demonstrate InGaAs mid-infrared quantum well infrared photodetectors (MIR PV-QWIPs) that enable cost-effective mature GaAs-based detection and imaging technologies, with exceptional material uniformity, reproducibility, and yield, over a large area, with high spectral selectivity, innate polarization sensitivity, radiation hardness, high detectivity, and high speed operation at TEC temperatures without bias.

Colloidal quantum-dot photodetectors exploiting multiexciton generation.

Multiexciton generation (MEG) has been indirectly observed in colloidal quantum dots, both in solution and the solid state, but has not yet been shown to enhance photocurrent in an optoelectronic device. Here, we report a class of solution-processed photoconductive detectors, sensitive in the ultraviolet, visible, and the infrared, in which the internal gain is dramatically enhanced for photon energies Ephoton greater than 2.7 times the quantum-confined bandgap Ebandgap. Three thin-film devices with different quantum-confined bandgaps (set by the size of their constituent lead sulfide nanoparticles) show enhancement determined by the bandgap-normalized photon energy, Ephoton/Ebandgap, which is a clear signature of MEG. The findings point to a valuable role for MEG in enhancing the photocurrent in a solid-state optoelectronic device. We compare the conditions on carrier excitation, recombination, and transport for photoconductive versus photovoltaic devices to benefit from MEG.

Heavy-metal-free solution-processed nanoparticle-based photodetectors: doping of intrinsic vacancies enables engineering of sensitivity and speed.

Photodetection in semiconductors enables digital imaging, spectroscopy, and optical communications. Integration of solution-processed light-sensing materials with a range of substrates offers access to new spectral regimes, the prospect of enhanced sensitivity, and compatibility with flexible electronics. Photoconductive photodetectors based on solution-cast nanocrystals have shown tremendous progress in recent years; however, high-performance reports to date have employed Pb- and Cd-containing materials. Here we report a high-sensitivity (photon-to-electron gain >40), high-speed (video-frame-rate-compatible) photoconductive photodetector based on In(2)S(3). Only by decreasing the energetic depth of hole traps associated with intrinsic vacancies in beta-phase In(2)S(3) were we able to achieve this needed combination of sensitivity and speed. Our incorporation of Cu(+) cations into beta-In(2)S(3)'s spinel vacancies that led to acceptable temporal response in the devices showcases the practicality of incorporating dopants into nanoparticles. The devices are stable in air and under heating to 215 degrees C, advantages rooted in the reliance on the stable inclusion of dopants into available sites instead of surface oxide species.

Highly luminescent lead sulfide nanocrystals in organic solvents and water through ligand exchange with poly(acrylic acid).

Hydrophobic lead sulfide quantum dots (PbS/OA) synthesized in the presence of oleic acid were transferred from nonpolar organic solvents to polar solvents such as alcohols and water by a simple ligand exchange with poly(acrylic acid) (PAA). Ligand exchange took place rapidly at room temperature When a colloidal solution of PbS/OA in tetrahydrofuran (THF) was treated with excess PAA, the PbS/PAA nanocrystals that formed were insoluble in hexane and toluene but could be dissolved in methanol or water, where they formed colloidal solutions that were stable for months. Ligand exchange was accompanied by a small blue shift in the band-edge absorption, consistent with a small reduction in particle size. While there was a decrease in quantum yield associated with ligand exchange and transfer to polar solvents, as is commonly found for colloidal quantum dots, the quantum yields determined were impressively high: PbS/OA in toluene (82%) and in THF (58%); PbS/PAA in THF (42%) and in water (24%). The quantum yields for the PbS/PAA solutions decreased over time as the solutions were allowed to age in the presence of air.

Efficient, stable infrared photovoltaics based on solution-cast colloidal quantum dots.

Half of the sun's power lies in the infrared. As a result, the optimal bandgaps for solar cells in both the single-junction and even the tandem architectures lie beyond 850 nm. However, progress in low-cost, large-area, physically flexible solar cells has instead been made in organic and polymer materials possessing absorption onsets in the visible. Recent advances have been achieved in solution-cast infrared photovoltaics through the use of colloidal quantum dots. Here we report stable solution-processed photovoltaic devices having 3.6% power conversion efficiency in the infrared. The use of a strongly bound bidentate linker, benzenedithiol, ensures device stability over weeks. The devices reach external quantum efficiencies of 46% in the infrared and 70% across the visible. We investigate in detail the physical mechanisms underlying the operation of this class of device. In contrast with drift-dominated behavior in recent reports of PbS quantum dot photovoltaics, we find that diffusion of electrons and holes over hundreds of nanometers through our PbSe colloidal quantum dot solid is chiefly responsible for the high external quantum efficiencies obtained in this new class of devices.

Nucleotide-directed growth of semiconductor nanocrystals.

We engineer colloidal quantum dot nanocrystals through the choice of biomolecular ligands responsible for nanoparticle nucleation, growth, stabilization, and passivation. We systematically vary the presence of, and thereby elucidate the role of, phosphate groups and a multiplicity of functionalities on the mononucleotides used as ligands. The results provide the basis for synthesis of nanoparticles using precisely controlled synthetic oligonucleotide sequences.