Life Course Epidemiology of Hip Osteoarthritis in Japan: A Multicenter, Cross-Sectional Study.

BACKGROUND: The incidence of developmental dysplasia of the hip (DDH) in Japanese newborns has reduced drastically following a primary prevention campaign initiated around 1972 to 1973; this perinatal education campaign promoted maintaining the hips of newborns in the naturally flexed-leg position. The purpose of the present study was to describe the life course epidemiology of hip osteoarthritis (OA) in adolescent and adult patients and to assess its association with exposure to the primary prevention campaign for DDH. METHODS: We included new patients with hip OA diagnosed from January 1, 2022, to December 31, 2022, at 12 core hospitals (8 special-function hospitals and 4 regional medical care support hospitals). The trend in the percentage of hips with a history of DDH treatment in childhood was estimated with use of a centered moving average using the birth year of the patient. We compared the prevalence of severe subluxation (Crowe type II, III, or IV) between patients with secondary hip OA due to hip dysplasia who were born in or before 1972 and those who were born in or after 1973. RESULTS: Overall, 1,095 patients (1,381 hips) were included. The mean age at the time of the survey was 63.5 years (range, 15 to 95 years). A total of 795 patients (1,019 hips; 73.8% of hips) were diagnosed with secondary OA due to hip dysplasia. Approximately 13% to 15% of hips among patients born from 1963 to 1972 had a history of DDH treatment in childhood; however, the percentage decreased among patients born in or after 1973. The prevalence of severe subluxation (Crowe type II, III, or IV) among patients born in or after 1973 was 2.4%, which was significantly less than that among patients born in or before 1972 (11.1%; odds ratio, 0.20; p < 0.001). CONCLUSIONS: As of 2022, secondary hip OA due to hip dysplasia is still responsible for most new cases of adolescent and adult hip OA seen in core hospitals in Japan. However, the perinatal education campaign initiated 50 years ago, which utilized a population approach and advocated for maintaining the hips of newborns in the naturally flexed-leg position, may have improved the environmental factors of DDH, as indicated by the apparently reduced need for treatment of DDH in childhood and the associated severe subluxation. This may result in a reduced need for challenging hip surgery later in life. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Calaxin is required for asymmetric bend initiation and propagation in sperm flagella.

Regulation of waveform asymmetry in flagella is critical for changes in direction when sperm are swimming, as seen during the chemotaxis of sperm towards eggs. Ca2+ is an important regulator of asymmetry in flagellar waveforms. A calcium sensor protein, calaxin, is associated with the outer arm dynein and plays a key role in the regulation of flagellar motility in a Ca2+-dependent manner. However, the underlying mechanism of regulating asymmetric waves by means of Ca2+ and calaxin remains unclear. To clarify the calaxin-dependent mechanism for generating Ca2+-dependent asymmetric flagellar waveforms, we analyzed the initial step of flagellar bend formation and propagation in the sperm of the ascidian Ciona intestinalis. Our experiment used demembranated sperm cells, which were then reactivated by UV flash photolysis of caged ATP under both high and low Ca2+ concentrations. Here, we show that initial bends in the flagella are formed at the base of the sperm and propagate towards the tip during waveform generation. However, the direction of the initial bend differed between asymmetric and symmetric waves. When a calaxin inhibitor (repaglinide) was applied, it resulted in the failure of asymmetric wave formation and propagation. This was because repaglinide had no effect on initial bend formation, but it significantly inhibited the generation of the subsequent bend in the reverse direction. Switching of dynein sliding activity by mechanical feedback is crucial for flagellar oscillation. Our results suggest that the Ca2+/calaxin mechanism plays an important role in the switching of dynein activity from microtubule sliding in the principal bend into the suppressed sliding in the reverse bend, thereby allowing the sperm to successfully change direction.

Gravitactic Swimming of the Planula Larva of the Coral Acropora: Characterization of Straightforward Vertical Swimming.

Vertical migration as well as horizontal dispersion is important in the ecological strategy of planktonic larvae of sedentary corals. We report in this paper unique vertical swimming behavior of planulae of the reef-building coral Acropora tenuis. Several days after fertilization, most of the planulae stayed exclusively at either the top or the bottom of the rearing tank. A good proportion of the planulae migrated almost vertically between top and bottom with fairly straight trajectories. Planulae sometimes switched their swimming direction via a sharp turn between the opposite directions. Quantitative analyses demonstrated that planulae kept constant speed while swimming either upward or downward, in contrast to frequent changes of direction and speed in horizontal swimming. Statistical comparison of propulsive speeds, estimated from swimming speeds and passive sedimentation, revealed gravikinesis of planulae, where the propulsive speed was significantly greater in downward swimming than upward swimming. The larval density hydrodynamically estimated was 0.25% lower than sea water density, which might be explained by the large quantity of lipids in planulae. Also, the deciliated larvae tended to orient oral end-up during floatation, presumably due to asymmetrical distribution of the endogenous light lipids. Plasticity of the larval tissue geometry could easily cause relocation of the center of forces which work together to generate gravitactic-orientation torque and, therefore, abrupt changing of the gravitactic swimming direction. The bimodal gravitactic behavior may give a new insight into dispersal and recruitment of coral larvae.

Spawning-Induced pH Increase Activates Sperm Attraction and Fertilization Abilities in Eggs of the Ascidian, Phallusia philippinensis and Ciona intestinalis.

In Phlebobranchiata ascidians, oocytes and spermatozoa are stored in the oviduct and spermiduct, respectively, until spawning occurs. Gametes in the gonoducts are mature and fertilizable; however, it was found that the gametes of the ascidians Phallusia philippinensis and Ciona intestinalis could not undergo fertilization in the gonoductal fluids. The body fluids of the ascidians, especially in the gonoducts, were much more acidic (pH 5.5-6.8) than seawater (pH 8.2), and the fertilization rate was low under such acidic conditions. Hence, we examined the effect of pH on gametes. Pre-incubation of gonoductal eggs at pH 8.2 prior to insemination increased fertilization rates, even when insemination was performed under low pH conditions. Furthermore, an increase in ambient pH induced an increase in the intracellular pH of the eggs. It was also found that an increase in ambient pH triggered the release of sperm attractants from the egg and is therefore necessary for sperm chemotaxis. Hence, acidic conditions in the gonoductal fluids keep the gametes, especially eggs, infertile, and the release of eggs into seawater upon spawning induces an increase in ambient pH, which enables egg fertilization.

Vitamin D status-associated postoperative complications in patients with hip dysplasia after periacetabular osteotomy: A case-control study.

OBJECTIVES: This study aimed to clarify the relationship between vitamin D status and complications after periacetabular osteotomy. METHODS: A total of 46 hips of 39 patients (3 men and 36 women; mean age at surgery, 41.0 years; mean postoperative follow-up duration, 63 months) were reviewed to obtain the following information: patients' serum 25-hydroxyvitamin D [25(OH)D] status, prevalence of postoperative delayed union of osteotomy sites in the greater trochanter (DUGT) and ischiopubic stress fractures (IPSFs), and risk factors. RESULTS: The mean serum 25(OH)D level was 11.9 ng/ml. DUGT and IPSF were found in four (10.3%) and three (7.7%) patients, respectively. Serum 25(OH)D levels ≤ 11 ng/ml were significantly associated with DUGT in female patients (p = .02). Serum 25(OH)D levels ≤ 9 ng/ml and smoking were significantly associated with IPSF (p = 0.01 and 0.02, respectively). Overall, 21.7% of patients with serum 25(OH)D levels ≤ 11 ng/ml developed at least one complication; no complications occurred when serum 25(OH)D levels were >11 ng/ml. CONCLUSION: Severe vitamin D deficiency was highly prevalent in relatively young patients. Vitamin D deficiency and smoking were independent risk factors for postoperative complications. Proactive supplementation is advisable to reduce postoperative complications, especially in patients with serum 25(OH)D levels ≤ 11 ng/ml.

Acquirement of the autonomic nervous system modulation evaluated by heart rate variability in medaka (Oryzias latipes).

Small teleosts have recently been established as models of human diseases. However, measuring heart rate by electrocardiography is highly invasive for small fish and not widely used. The physiological nature and function of vertebrate autonomic nervous system (ANS) modulation of the heart has traditionally been investigated in larvae, transparent but with an immature ANS, or in anesthetized adults, whose ANS activity may possibly be disturbed under anesthesia. Here, we defined the frequency characteristics of heart rate variability (HRV) modulated by the ANS from observations of heart movement in high-speed movie images and changes in ANS regulation under environmental stimulation in unanesthetized adult medaka (Oryzias latipes). The HRV was significantly reduced by atropine (1 mM) in the 0.25-0.65 Hz and by propranolol (100 µM) at 0.65-1.25 Hz range, suggesting that HRV in adult medaka is modulated by both the parasympathetic and sympathetic nervous systems within these frequency ranges. Such modulations of HRV by the ANS in adult medaka were remarkably suppressed under anesthesia and continuous exposure to light suppressed HRV only in the 0.25-0.65 Hz range, indicating parasympathetic withdrawal. Furthermore, pre-hatching embryos did not show HRV and the power of HRV developed as fish grew. These results strongly suggest that ANS modulation of the heart in adult medaka is frequency-dependent phenomenon, and that the impact of long-term environmental stimuli on ANS activities, in addition to development of ANS activities, can be precisely evaluated in medaka using the presented method.

Risk factors for radiological changes after bipolar hemiarthroplasty for osteonecrosis of the femoral head.

OBJECTIVES: This study aimed to report the mid-term radiological outcomes of patients with bipolar hemiarthroplasty (BHA) for stage 3 osteonecrosis of the femoral head (ONFH), and to identify the risk factors for postoperative radiological changes. METHODS: We retrospectively investigated 62 patients (38 men and 24 women; mean age, 50.1 years) aged <70 years who underwent primary BHA for Association Research Circulation Osseous stage 3 ONFH between 1998 and 2010. The mean follow-up period after BHA was 12.8 years. The following changes were assessed on follow-up radiographs: outer head migration, polyethylene wear, and femoral osteolysis. The association between demographic data and the development of postoperative radiological changes was evaluated. RESULTS: Radiological changes were found in 20 hips (32.3%) at a mean of 8.1 years after BHA; of these, three hips (4.8%) underwent total hip arthroplasty conversion at a mean of 10.9 years after BHA. Both univariate and multivariate analysis revealed that younger age and female sex were independent risk factors for the development of postoperative radiological changes. CONCLUSION: The current results suggest that the indication of BHA should be carefully determined in young or female patients with ONFH, even when the disease is in the early stage.

Proximal femoral morphology after transtrochanteric posterior rotational osteotomy for osteonecrosis of the femoral head: A three-dimensional simulation study.

BACKGROUND: Transtrochanteric posterior rotational osteotomy (PRO) is one of the joint-preserving surgeries for osteonecrosis of the femoral head. In general, postoperative femoral neck-shaft varus realignment is planned to obtain a sufficient intact articular surface of the femoral head in the weight-bearing portion. Unlike anterior rotational osteotomy, PRO allows for more than 90° rotation of the femoral head, resulting in more complicated morphology. However, little is known about the potential risk of postoperative femoral retroversion after PRO. This simulation study aims: 1) to assess whether postoperative femoral neck-shaft varus realignment can coexist with preserved femoral anteversion after PRO, 2) and whether postoperative proximal femoral morphology could be predicted with approximation equations. HYPOTHESIS: High degree (>90°) PRO is favourable for femoral neck-shaft varus realignment, but unfavourable for maintaining postoperative femoral anteversion. MATERIALS AND METHODS: PRO was simulated by using CT data from 10 hips in 10 healthy volunteers. During simulation, the intertrochanteric osteotomy plane was determined three-dimensionally based on anteroposterior-view line (the osteotomy line on anteroposterior view) and lateral-view line (the osteotomy line on lateral view). By changing either the angle of anteroposterior-view line or lateral-view line, we simulated 90°, 110°, 130° and 150° PRO. To clarify the effects of various posterior rotation angles on postoperative proximal femoral morphology, we made simplified PRO models through changing only the posterior rotation angle. RESULTS: In the 90°, 110°, 130° and 150° PRO models, the vertically inclined angle of anteroposterior-view line showed a significant positive correlation with femoral neck-shaft varus realignment (90° PRO, r=0.90; 110° PRO, r=0.95; 130° PRO, r=0.97; 150° PRO, r=0.99), while a significant negative correlation with postoperative femoral anteversion angle (90° PRO, r=-0.97; 110° PRO, r=-0.95; 130° PRO, r=-0.92; 150° PRO, r=-0.7). Likewise, the posteriorly tilted angle of lateral-view line showed a significant negative correlation with both femoral neck-shaft varus realignment (90° PRO, r=-0.81; 110° PRO, r=-0.81; 130° PRO, r=-0.79; 150° PRO, r=-0.72) and postoperative femoral anteversion angle (90° PRO, r=-0.90; 110° PRO, r=-0.89; 130° PRO, r=-0.92; 150° PRO, r=-0.88). In the simplified PRO models, the posterior rotation angle showed a significant positive correlation with femoral neck-shaft varus realignment (r=0.33), while a significant negative correlation with postoperative femoral anteversion angle (r=-0.76). The approximation equations for predicting the proximal femoral morphology after PRO were validated. DISCUSSIONS: It was confirmed that high-degree PRO (>90°) is favourable for femoral neck-shaft varus realignment, but works against preserving femoral anteversion. With the approximation equations developed in the current study, surgeons could examine the feasibility of PRO based on postoperative femoral anteversion. In terms of hip joint function and subsequent total hip arthroplasty, excessive deformities including femoral retroversion and severe varus deformity could be avoided. LEVEL OF EVIDENCE: IV; case series without control group.

Differences in the microarchitectural features of the lateral collapsed lesion between osteonecrosis and subchondral insufficiency fracture of the femoral head.

BACKGROUND: Like osteonecrosis of the femoral head (ONFH), subchondral insufficiency fracture of the femoral head (SIF) causes femoral head collapse. However, little is known about the differences between the two diseases regarding the morphological features of the collapsed lesion. We tested the hypothesis that the morphological features of the lateral collapsed lesion would differ between ONFH and SIF. METHODS: Twenty femoral heads histopathologically diagnosed as ONFH (n = 10) or SIF (n = 10) were used in this study. In the lateral collapsed lesion of each femoral head, cubic regions of interest (ROIs) were selected within the collapsed subchondral area and the nearby non-collapsed subchondral area. Micro-CT-based microarchitectural parameters were compared between the ROIs in each disease. Additionally, correlations between histopathological and microarchitectural features were evaluated. RESULTS: In ONFH, bone volume fraction, trabecular thickness, and bone mineral density in the collapsed area were all significantly lower than those in the nearby non-collapsed area where thickened bone trabeculae accompanied by appositional bone formation were invariably seen. On the other hand, in SIF there were no significant differences between the ROIs in any of these microarchitectural parameters. Histopathologically, varying degrees of callus formation overlying the fracture of the subchondral plate were seen around the lateral collapsed lesion. CONCLUSION: The morphological features of the lateral collapsed lesion were inconsistent between ONFH and SIF, suggesting different pathomechanisms of femoral head collapse.

Is bone mineral density lower in the necrotic lesion in pre-collapse osteonecrosis of the femoral head?

The purpose of this study was to clarify whether bone mineral density (BMD) of the necrotic lesion in precollapse osteonecrosis of the femoral head (ONFH) is reduced according to Hounsfield unit (HU) values on computed tomography (CT). The superior one-third of the femoral head in the coronal section was set as the region of interest (ROI) for the measurement of HU values. First, HU values of 101 control participants were assessed to identify relevant confounding factors. Next, the relationship between HU values and BMD on dual-energy X-ray absorptiometry (DXA) was verified. Then the mean HU value of the ROI in patients with pre-collapse ONFH was compared with that in propensity score-matched control participants. Finally, the HU values of the lateral boundary in the patients with and without subsequent collapse were compared. Multivariable analysis showed that both age and BMI were significantly correlated with the HU value, which showed a strong correlation with the BMD of the femoral neck on DXA (r = 0.92). In 25 ONFH patients and 25 propensity-matched control participants, no significant difference was found in the HU value of the ROI (p = .54). The mean HU value of the lateral boundary in patients with subsequent collapse was found to be significantly higher than that in patients without subsequent collapse (p < .01). The assessment of HU values on CT was useful for the evaluation of BMD of the femoral head. The current assessment did not demonstrate reduced bone mineral density of the necrotic lesion in pre-collapse ONFH.

Quantitative evaluation of bone-resorptive lesion volume in osteonecrosis of the femoral head using micro-computed tomography.

Objectives To quantify the volume of bone-resorptive lesions in post-collapse osteonecrosis of the femoral head (ONFH) using micro-computed tomography (micro-CT) and assess their characteristics in post-collapse ONFH. Methods We investigated 35 femoral heads resected from 35 patients with ONFH (20 men and 15 women; mean age, 47.2 years). On each of seven coronal high-resolution micro-CT slices of the femoral head, the bone-resorptive areas were extracted using bone microstructure measurement software. Next, the total bone-resorptive volume ratio, defined as the ratio of all bone-resorptive cross-sectional areas to all femoral head cross-sectional areas in all seven slices, was calculated. Associations between total bone-resorptive volume ratio and sex, age, ONFH-associated factors, patient workload levels, ONFH stage, ONFH type, necrotic volume on magnetic resonance imaging, and duration from the onset of pain to surgery were analyzed. Lesion location and the association between bone-resorptive lesion and collapse were also evaluated. Results The mean total bone-resorptive volume ratio was 7.0±6.0%, which varied significantly by ONFH stage (ARCO collapse quantitation 3A, 3.5±2.1%; 3B, 6.8±3.0%; and 3C, 13.6±8.8%). ONFH stage was independently associated with total bone-resorptive volume ratio (P<0.05). Furthermore, high bone-resorptive volume ratios were found in the anterior femoral head and were associated with collapse. Conclusions This study demonstrated that bone-resorptive volume in post-collapse ONFH was significantly associated with the disease stage, which was more widespread in the anterior portion of the femoral head than in the posterior portion.

Dominant nonlocal superconducting proximity effect due to electron-electron interaction in a ballistic double nanowire.

Cooper pair splitting (CPS) can induce nonlocal correlation between two normal conductors that are coupled to a superconductor. CPS in a double one-dimensional electron gas is an appropriate platform for extracting a large number of entangled electron pairs and is one of the key ingredients for engineering Majorana fermions with no magnetic field. In this study, we investigated CPS by using a Josephson junction of a gate-tunable ballistic InAs double nanowire. The measured switching current into the two nanowires is significantly larger than the sum of the switching current into the respective nanowires, indicating that interwire superconductivity is dominant compared with intrawire superconductivity. From its dependence on the number of propagating channels in the nanowires, the observed CPS is assigned to one-dimensional electron-electron interaction. Our results will pave the way for the utilization of one-dimensional electron-electron interaction to reveal the physics of high-efficiency CPS and to engineer Majorana fermions in double nanowire systems via CPS.

Differences in magnetic resonance findings between symptomatic and asymptomatic pre-collapse osteonecrosis of the femoral head.

PURPOSE: The purpose of this study was to assess the differences in magnetic resonance (MR) findings between the symptomatic and asymptomatic pre-collapse stage of osteonecrosis of the femoral head (ONFH). MATERIALS AND METHODS: This study reviewed 123 consecutive hips in 91 patients in the pre-collapse stage of ONFH based on plain radiographic findings. These 123 hips were divided into symptomatic and asymptomatic groups according to the pain domain score in the Harris hip score system. Bone marrow edema (BME), synovial fluid effusion, and subchondral fracture were evaluated using MR imaging. Odds ratios (ORs) were calculated between these three parameters and symptoms. The subsequent clinical course after MR examination was also assessed for each hip that could be followed more than 1 year. RESULTS: Forty-six hips (37.4%) were categorized as symptomatic and 77 hips (62.6%) as asymptomatic. The prevalence of BME, synovial fluid effusion, and subchondral fracture were 87.0% (40/46), 80.4% (37/46), and 34.8% (16/46), respectively, in the symptomatic group, and 0%, 28.6% (22/77), and 0%, respectively, in the asymptomatic group, indicating significant differences between the two groups (p < 0.0001). Among these parameters, BME showed the highest OR with regard to the presence or absence of symptoms (BME, 965.8; joint effusion, 10.3; subchondral fracture, 83.9). Due to persistent pain and subsequent collapse, 30 of 35 (85.7%) symptomatic hips with BME subsequently underwent surgical treatment at a mean interval of 3.47 months after MR examination, while 25 of 66 (37.9%) asymptomatic hips without BME underwent surgical treatment at a mean interval of 20.7 months after MR examination. CONCLUSIONS: This study demonstrated that symptomatic pre-collapse ONFH diagnosed based on plain radiographic findings could be distinguished from asymptomatic pre-collapse ONFH by the presence of BME on MR imaging, and thus BME may be a sign of occult fracture.

Volume of hip synovitis detected on contrast-enhanced magnetic resonance imaging is associated with disease severity after collapse in osteonecrosis of the femoral head.

OBJECTIVE: To evaluate the relationship between the volume of hip synovitis detected on contrast-enhanced magnetic resonance imaging (MRI) and the disease stage of osteonecrosis of the femoral head (ONFH). MATERIALS AND METHODS: Sixty-three consecutive hips in 40 ONFH patients were reviewed using contrast-enhanced MRI. Ten unaffected hips in 10 patients with unilateral ONFH were used as controls. Based on the Japanese Investigation Committee system, these hips were classified according to stage and type. The volume and location of hip synovitis were semi-quantitatively measured on contrast-enhanced MRI. Clinicoradiological factors were statistically analyzed to determine the relationship with the volume of hip synovitis. RESULTS: The mean synovial volume was significantly larger in ONFH hips (8,020 ± 6,900 mm3) than in controls (910 ± 1,320 mm3; p = 0.001). The area of synovitis in the anterior portion of the hip joint was double (mean: 2.17 ± 1.77) that in the posterior portion. The volume of synovitis was small in pre-collapse-stage hips (stage 1: 680 ± 690 mm3, stage 2: 1,460 ± 1,200 mm3), but significantly larger in post-collapse-stage hips (stage 3A: 7,820 ± 4,490 mm3, stage 3B: 13,850 ± 7,110 mm3; p < 0.001). Multiple regression analysis showed that disease stage was the only factor related to hip synovitis. CONCLUSIONS: Our study suggests that hip synovitis in ONFH might occur after femoral head collapse and worsen with collapse progression, mainly in the anterior portion.

Effects of sclerotic changes on stress concentration in early-stage osteonecrosis: A patient-specific, 3D finite element analysis.

Stress distribution remains unclear in early-stage osteonecrosis of the femoral head (ONFH). To clarify this issue, we generated patient-specific finite element models (FEMs) from 51 patients with ONFH. Patients' hips were classified into three groups: ONFH without a sclerotic boundary (Stage 1, n = 6), ONFH with a sclerotic boundary (Stage 2, n = 10), and ONFH with both a sclerotic boundary and <2 mm collapse (Stage 3, n = 35). Four hips without ONFH were used as controls. Stress distribution in each FEM was compared with magnetic resonance imaging (MRI) and computed tomography (CT) results. Fifteen wholly resected femoral heads in Stage 3 hips were assessed by micro-CT. Furthermore, we histologically examined three Stage 2 femoral heads that subsequently developed subchondral fractures after FEM analyses. In all FEMs of both control and Stage 1 hip, stress was equally distributed on the femoral head surface. However, in all FEMs of both Stages 2 and 3 hips, stress was concentrated at the lateral boundary of the femoral head surface, corresponding to both a low-intensity band on T1-weighted MRI images and sclerotic changes on CT. On micro-CT, subchondral fractures consistently began at the lateral boundary with sclerotic changes, in which bone volume fraction was increased. Histology showed breakage of subchondral plates at the junction between necrotic and reparative zones. In early-stage ONFH, sclerotic changes caused stress concentration, which can trigger subchondral fractures at the lateral boundary. Clinical Significance: Our results will clarify the pathogenic mechanism of collapse in ONFH. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3169-3177, 2018.

Equal-Spin Andreev Reflection on Junctions of Spin-Resolved Quantum Hall Bulk State and Spin-Singlet Superconductor.

The recent development of superconducting spintronics has revealed the spin-triplet superconducting proximity effect from a spin-singlet superconductor into a spin-polarized normal metal. In addition recently superconducting junctions using semiconductors are in demand for highly controlled experiments to engineer topological superconductivity. Here we report experimental observation of Andreev reflection in junctions of spin-resolved quantum Hall (QH) states in an InAs quantum well and the spin-singlet superconductor NbTi. The measured conductance indicates a sub-gap feature and two peaks on the outer side of the sub-gap feature in the QH plateau-transition regime increases. The observed structures can be explained by considering transport with Andreev reflection from two channels, one originating from equal-spin Andreev reflection intermediated by spin-flip processes and second arising from normal Andreev reflection. This result indicates the possibility to induce the superconducting proximity gap in the the QH bulk state, and the possibility for the development of superconducting spintronics in semiconductor devices.

The effect of the anterior boundary of necrotic lesion on the occurrence of collapse in osteonecrosis of the femoral head.

PURPOSE: The location of the necrotic lesion is one of the important factors for collapse in osteonecrosis of the femoral head (ONFH). The significance of anterior localization has been little studied. This study evaluated the effects of anterior boundary of a necrotic lesion on collapse. METHODS: We reviewed the outcomes of 113 consecutive non-collapsed asymptomatic hips in 98 ONFH patients with mean follow-up of 4.7 years (2.0-11.8) after the initial magnetic resonance (MR) imaging. The presence or absence of collapse was investigated using follow-up radiographs. The location of the anterior boundary of a necrotic lesion was assessed using the anterior necrotic angle between the midline of the femoral neck shaft and the line passing from the femoral head centre to the anterior boundary on mid-oblique MR imaging. Multivariate analysis was performed to identify risk factors for collapse, and further analyses were executed according to the lateral boundary of the necrotic lesion. RESULTS: During the follow-up period, collapse was confirmed in 61 hips (54.0%). Multivariate analysis revealed that the anterior necrotic angle was independently associated with collapse as well as the lateral boundary of the necrotic lesion. When the lateral boundary was located at the middle third of weight-bearing portion (32 hips), that was generally categorized as a low risk of collapse, all five cases with anterior necrotic angle ≥ 79° developed collapse, whereas only one of 27 cases (3.7%) with an anterior necrotic angle < 79° developed collapse (p < 0.0001). CONCLUSIONS: This study indicates that ONFH patients with anterior localization of a necrotic lesion can develop collapse even if the necrotic lesion is medially located.