Dislocation Group Research Articles

Instability after hip hemiarthroplasty for femoral neck fracture: an unresolved problem.

Background:The dislocated hip hemiarthroplasty (HA) remains a difficult condition to treat owing to frailty, comorbidity, poor quality of bone and soft tissues. We aimed to identify parameters contributing to instability following hip HA and describe the operative management and patient outcomes.Methods:We retrospectively reviewed consecutive cases of all patients with hip fracture treated between 2004 and 2019 at a single tertiary care institution. We propensity matched patients with and without hip dislocations on a 1:2 basis for age, sex, and approach. We reviewed risk factors for HA dislocation, performed radiographic measurements, and recorded management of dislocation and further complications.Results:Of the 1472 patients treated with HA, we included 18 patients (1.2%) who sustained at least 1 dislocation in our analysis. Of the dislocations identified, 13 and 17 occurred within 1 and 3 months postoperative, respectively. The presence of dementia and low preoperative lateral centre-edge angle were associated with increased risk of dislocation. The 2-year mortality rate was significantly higher in the dislocation group (n = 9) than the control group (n = 2) (p = 0.0003). Nine of 18 (50%) patients were treated with an initial closed reduction; 5 of these 9 (56%) sustained further dislocations and required additional treatment. Six of 18 cases were treated with a total hip arthroplasty after their first dislocation. By final follow-up, 2 of 18 patients had Girdlestone procedures.Conclusion:This study highlights patient factors associated with increased dislocation risk following hip HA. A thorough preoperative assessment is indicated when presented with dislocated HA to prevent further complications.

Computed Tomography Imaging Analysis of the MPFL Femoral Footprint Morphology and the Saddle Sulcus: Evaluation of 1094 Knees.

Background:The medial patellofemoral ligament (MPFL) has been reported to be anatomically attached from an osseous saddle region (saddle sulcus) between neighboring landmarks on the femur, including the adductor tubercle (AT), medial epicondyle (ME), and medial gastrocnemius tubercle (MGT). However, the position and prevalence of the saddle sulcus remain unknown.Purpose:To study the femoral footprint of MPFL and the prevalence of the saddle sulcus with computed tomography (CT) imaging; quantify the position of the saddle sulcus; and determine the relevant factors of the identified position and measuring distances.Study Design:Cross-sectional study; Level of evidence, 3.Methods:A total of 1094 knees in 753 patients were studied. Knees were organized into an anterior cruciate ligament reconstruction (ACLR) group (controls) and a recurrent patellar dislocation (RPD) group. Using 3-dimensionally reconstructed CT images, the authors determined the prevalence of the saddle sulcus and its position relative to the AT, the ME, the Schöttle point (1.3 mm anterior to the distal posterior cortex and 2.5 mm distal to the posterior origin of the medial femoral condyle), and the Fujino point (approximately 10 mm distal to the AT). Analysis of covariance was used to adjust for age, sex, side, and body mass index on the measurements.Results:There were 555 knees in the control group and 539 knees in the RPD group. The MPFL femoral footprint presented as an oblique, oblong, osseous region (saddle sulcus) in 75.7% of knees (75.0%, ACLR group vs 76.4%, RPD group; P < .001). The saddle sulcus was located a mean of 12.2 mm (95% CI, 12.0-12.4 mm) from a line connecting the apex of the AT to the ME (AT-ME) and a mean of 7.6 mm (95% CI, 7.5-7.8 mm) posteriorly perpendicular to that line. The location as a proportion of the AT-ME distance was 63.1% (95% CI, 62.6%-63.7%) in the X direction and 39.8% (95% CI, 39.1%-40.5%) in the Y direction. The Schöttle and Fujino points lay anterior and proximal to the saddle sulcus more than 5 mm away from the center of the saddle sulcus. Women had a higher prevalence of saddle sulcus (odds ratio [OR], 1.33 [95% CI, 1.00-1.75]; P = .046) compared with men.Conclusion:The saddle sulcus was identified in 75.7% of knees from the medial femoral aspect, with its center located consistently between the AT and ME.

Phase field crystal simulation of strain-induced square phase low-angle symmetric tilt grain boundary dislocation reaction

In this paper, the phase field crystal method is used to study the dislocation motion and reaction of the square phase symmetric tilt low-angle grain boundaries, and the dislocation configurations with different misorientation angles are analyzed under the action of applied strain. The geometric phase approach is used to characterize the strain field around the dislocations. The results show that after the solidification relaxation, the interfacial dislocations on both sides of the grain are distributed in parallel but opposite direction. With the increase of misorientation angle between grains, the number of dislocations increases, the spacing between them decreases, and the free energy of the system increases. Imposed by the applied strain, the grain boundary dislocations undergo climbing, launching, and reactive annihilation, with the free energy fluctuating. When the misorientation increases, the dislocation motion mode changes from climbing to climbing-sliping, resulting in more dislocation group configurations, and more reactions between dislocations and dislocation groups. For the dislocation reactions of different configurations, positive shear strain drives dislocations to approach, and negative shear strain drives dislocations to annihilate.

Defect evolution in Y&lt;sub&gt;0.5&lt;/sub&gt;Gd&lt;sub&gt;0.5&lt;/sub&gt;Ba&lt;sub&gt;2&lt;/sub&gt;Cu&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;7–&lt;i&gt;δ&lt;/i&gt;&lt;/sub&gt; superconducting layer irradiated by H&lt;sup&gt;+&lt;/sup&gt; ions

&lt;sec&gt;In order to further improve the superconducting current carrying capacity of RE-Ba-Cu-O coated conductor under the action of strong magnetic field, ion irradiation is used to generate the pinning centers of introduced magnetic flux in the RE-Ba-Cu-O coated conductor. In this work, the H&lt;sup&gt;+&lt;/sup&gt;-ion irradiation of second-generation high-temperature superconductor RE-Ba-Cu-O strip is carried out by using the 320 kV high charge state ion synthesis research platform. Doppler broadened slow positron beam analysis combined with Raman spectroscopy is used to measure the change of microstructure in Y&lt;sub&gt;0.5&lt;/sub&gt;Gd&lt;sub&gt;0.5&lt;/sub&gt;Ba&lt;sub&gt;2&lt;/sub&gt;Cu&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;7–&lt;i&gt;δ&lt;/i&gt; &lt;/sub&gt;(YBCO) sample irradiated by H&lt;sup&gt;+&lt;/sup&gt; ions in a range of 5.0 × 10&lt;sup&gt;14&lt;/sup&gt;–1.0 × 10&lt;sup&gt;16&lt;/sup&gt; ions/cm&lt;sup&gt;2&lt;/sup&gt;. The positron annihilation parameters in YBCO before and after irradiation are analyzed. It is found that after 100 keV H&lt;sup&gt;+&lt;/sup&gt; ion irradiation, a large number of defects including vacancies, vacancy groups or dislocation groups are produced in the superconducting layer.&lt;/sec&gt;&lt;sec&gt;The larger the irradiation dose, the more the produced vacancy type defects are and the more complex the defect types, and the annihilation mechanism of positrons in the defects changes. Raman spectroscopy results show that with the increase of H&lt;sup&gt;+&lt;/sup&gt; ion irradiation dose, the oxygen atoms in the coating rearrange, the plane spacing increases, the orthogonal phase structure of the coating is destroyed, and the degree of order decreases. The defects produced by such an ion irradiation lay a foundation for the introduction of flux pinning centers. Further research can be carried out in combination with X-ray diffractometer, transmission electron microscope, superconductivity and other testing methods to provide theoretical and practical reference for the optimization of material properties.&lt;/sec&gt;

The effect of platelet-rich plasma on chondrocyte healing in traumatic dislocation of the hip in a rat model

Background/Aim: Traumatic hip dislocations (THD) are orthopedic emergencies and significant complications such as cartilage degeneration can be reduced with early reduction. This study aimed to examine the effect of platelet-rich plasma (PRP) on cartilage cells in one-, two- or 8-hours prolonged hip dislocation. Methods: We used 24 Sprague-Dawley rats in this study and divided them into three main groups based on whether their hips were in the protruding position for one, two, or eight hours. Each main group was further divided into two subgroups, with the right hips constituting the experimental group and the left hips, the control group. Traumatic hip dislocation modeling was performed surgically on both hips of the rats under anesthesia in the same session. After both dislocated joints were reduced and the hip capsules were sutured, platelet-rich plasma was administered to the right hips. After 1 week, all rats were sacrificed, their femoral heads were excised and subjected to histopathological examination. Terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end labeling (TUNEL) testing was used to show chondrocyte apoptosis in the femoral head. The apoptotic index (AI) showing the ratio of cartilage cells to apoptosis was calculated histopathologically. A comparison of apoptotic indices was made between the groups. Results: The AIs of the one-, two- and eight hours-long hip dislocation groups were 0.012 (0.005), 0.023 (0.011), 0.046 (0.012), respectively (P

Tibial Tuberosity-Trochlear Groove Distance and Its Components in Patients with and without Episodic Patellar Dislocation: A Study of 781 Knees.

The purposes of the present study were (1) to measure the tibial tuberosity-trochlear groove distance and its components with the knee in extension, (2) to determine their diagnostic performance in distinguishing between patients with and without episodic patellar dislocation, and (3) to investigate the relationship of each component to the total tibial tuberosity-trochlear groove distance. We retrospectively reviewed computed tomography (CT) images of the knee joint in a group of patients with episodic patellar dislocation and a group of control subjects who were treated for another type of knee disorder in our institution between 2015 and 2021. Tibial tuberosity-trochlear groove distance, tibial tubercle lateralization, trochlear groove medialization, and knee rotation were measured on axial images. Partial correlation analysis of the measured parameters was performed after adjusting for remaining variables. Receiver operating characteristic (ROC) curves and the areas under the ROC curves (AUCs) were assessed to assess the diagnostic accuracy. A subgroup analysis based on femoral trochlear dysplasia classification was also performed. After screening of 653 patients (947 knees) in our hospital's patient registry, a total of 521 patients (781 knees) were analyzed, including 541 knees (69.3%) with episodic patellar dislocation and 240 knees (30.7%) without episodic patellar dislocation (control group). The tibial tuberosity-trochlear groove distance demonstrated the best diagnostic performance, with the AUC being significantly better than that for other parameters (p < 0.001). The tibial tuberosity-trochlear groove distance was moderately to strongly correlated with knee rotation and trochlear groove medialization in the control and episodic patellar dislocation groups (p < 0.001). However, tibial tubercle lateralization showed a weak correlation with the tibial tuberosity-trochlear groove distance in the control group and moderate correlation in the episodic patellar dislocation group (p < 0.001). Knees with a type-D femoral trochlea had a significantly greater tibial tuberosity-trochlear groove distance than those with a type-A, B, or C femoral trochlea (p ≤ 0.011). Tibial tuberosity-trochlear groove distance, a reliable predictor of episodic patellar dislocation, was affected more by knee rotation and trochlear groove medialization and was less affected by tibial tubercle lateralization, and it increased with an increasing grade of femoral trochlear dysplasia. The correlation of the tibial tuberosity-trochlear groove distance and its components as noted in the current study will help to achieve a better understanding of the tibial tuberosity-trochlear groove distance. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Dislocation rate, revisions and other complications of primary cemented hemiarthroplasty for displaced femoral neck fractures: a single-center cohort study of 743 unselected hips with a mean 2.7-year follow-up.

Evidence of whether to use hemiarthroplasty (HA) or total hip arthroplasty for displaced femoral neck fractures (FNF) is still widely debated, especially when taking ambulatory status, age, and patient cognitive status into account. The current study aims to report the rates of dislocations, revisions and other complications for primary cemented HA in patients with displaced FNF. Single-center retrospective follow-up study of an unselected historic cohort. 743 consecutive hips (551W and 192M) at mean (SD) age of 83.6 (8.4) years received primary cemented HA for displaced FNF by posterolateral surgical approach between January 2012 and December 2019. Patient files and radiographs were evaluated for dislocations, revisions, and other complications until death or end of the follow-up period, and the educational level of the surgeon was noted. During a mean (SD) follow-up period of 2.7 (2.2) years, there were 6.1% (n = 45) dislocations, in which 82% (first dislocation) appeared within the first 30 postoperative days, and 51% (n = 23) of the dislocations requiring subsequent surgery. At the time of the last available follow-up, 57% (n = 421) of the patients were dead. A non-dislocation related revision was needed in 3.4% (n = 25) of the patients [in which infection accounted for 40% (n = 10) and traumatic periprosthetic fracture for 32% (n = 8)]. Thirty-day mortality was 9.2% and 1-year mortality 25.8%. There were no differences in patient's age, gender, or educational level of the surgeon between the dislocation and the no dislocation groups. Patients aged < 70years presented with a higher dislocation rate (p < 0.001) than the patients aged > 70years. Primary HA presents a safe and robust approach with acceptable complication rates in a genuine unselected cohort of displaced FNF, particularly for patients aged > 70.

Integrating the Combined Sagittal Index Reduces the Risk of Dislocation Following Total Hip Replacement.

The aims of this matched cohort study were to (1) assess differences in spinopelvic characteristics between patients who sustained a dislocation after total hip arthroplasty (THA) and a control group without a dislocation, (2) identify spinopelvic characteristics associated with the risk of dislocation, and (3) propose an algorithm including individual spinopelvic characteristics to define an optimized cup orientation target to minimize dislocation risk. Fifty patients with a history of THA dislocation (29 posterior and 21 anterior dislocations) were matched for age, sex, body mass index (BMI), index diagnosis, surgical approach, and femoral head size with 200 controls. All patients underwent detailed quasi-static radiographic evaluations of the coronal (offset, center of rotation, and cup inclination/anteversion) and sagittal (pelvic tilt [PT], sacral slope [SS], pelvic incidence [PI], lumbar lordosis [LL], pelvic-femoral angle [PFA], and cup anteinclination [AI]) reconstructions. The spinopelvic balance (PI - LL), combined sagittal index (CSI = PFA + cup AI), and Hip-User Index were determined. Parameters were compared between the control and dislocation groups (2-group analysis) and between the controls and 2 dislocation groups identified according to the direction of the dislocation (3-group analysis). Important thresholds were determined from receiver operating characteristic (ROC) curve analyses and the mean values of the control group; thresholds were expanded incrementally in conjunction with running-hypothesis tests. There were no coronal differences, other than cup anteversion, between groups. However, most sagittal parameters (LL, PT, CSI, PI - LL, and Hip-User Index) differed significantly. The 3 strongest predictors of instability were PI - LL >10° (sensitivity of 70% and specificity of 65% for instability regardless of direction), CSIstanding of <216° (posterior instability), and CSIstanding of >244° (anterior instability). A CSI that was not between 205° and 245° on the standing radiograph (CSIstanding) was associated with a significantly increased dislocation risk (odds ratio [OR]: 4.2; 95% confidence interval [CI]: 2.2 to 8.2; p < 0.001). In patients with an unbalanced and/or rigid lumbar spine, a CSIstanding that was not 215° to 235° was associated with a significantly increased dislocation risk (OR: 5.1; 95% CI: 1.8 to 14.9; p = 0.001). Spinopelvic imbalance (PI - LL >10°) determined from a preoperative standing lateral spinopelvic radiograph can be a useful screening tool, alerting surgeons that a patient is at increased dislocation risk. Measurement of the PFA preoperatively provides valuable information to determine the optimum cup orientation to aim for a CSIstanding of 205° to 245°, which is associated with a reduced dislocation risk. For patients at increased dislocation risk due to spinopelvic imbalance (PI - LL >10°), the range for the optimum CSI is narrower. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Clinical, Genetic and Orthopedic Characteristics of Desbuquois Dysplasia

Introduction. Desbuquois dysplasia is a rare skeletal dysplasia with an autosomal recessive inheritance, resembling to the group of multiple joint dislocations. The disease is caused by mutations in the CANT1 and XYLT1 genes, the protein products of which are involved in the degradation of proteoglycans, which play an important role in endochondral ossification. The polymorphism of clinical and radiological characteristics and the genetic heterogeneity of Desbuquois dysplasia necessitate the description of the phenotypic characteristics of patients with various types of mutations, which optimize diagnosis. Objective description of the clinical and radiological characteristics of three Russian patients with Desbuquois dysplasia of types 1 and 2 with remarkable orthopedic manifestation, caused by mutations in the CANT1 and XYLT1 genes. Materials and Methods. Genealogical, clinical, radiographic and genetic data of three unrelated Russian patients aged 2 to 8 years was carried out. Genetic testing was carried out using clinical exome sequencing and methyl-sensitive PCR. Results. Two patients were diagnosed with type 1 disease due to a previously described homozygous mutation in the CANT1 gene: c.898CT (p.Arg300Cys), and one type 2 due to heterozygous mutations in the XYLT1 gene. One mutation: c.1651CT (p.Arg551Cys) was detected during exome sequencing, and the second mutation: expansion of GGC repeats in the promoter region of the gene, revealed by methyl-sensitive PCR of the first exon of the gene. The main clinical signs of the disease were micromelic dwarfism, hypermobility in the joints and specific facial dysmorphisms, radiographic analysis revealed characteristic monkey wrench appearance of the proximal femur in all 3 patients, additional ossification center of the second metacarpal, advanced bone age and multiple dislocations in the joints. The patients also had extra-skeletal manifestations (congenital glaucoma, obstructive bronchitis, renal hypoplasia and congenital heart malformations). Conclusion. Genetic heterogeneity and the presence of polymorphism of clinical manifestations make it possible to consider sequencing of the clinical exome as the optimal method for diagnosing Desbuquois dysplasia types 1 and 2. Analysis of the literature and the results of our molecular genetic data indicate the possibility of expansion of the GGC repeat in the XYLT1 gene in patients with clinical manifestations of type 2 Desbuquois dysplasia.

Patient-reported outcome after dislocation of primary total hip arthroplasties: a cross-sectional study derived from the Danish Hip Arthroplasty Register

Background and purpose — Knowledge regarding patient-reported outcomes (PROs) after dislocation and closed reduction is lacking. We report health- and hip-related quality of life (QoL) after dislocation, following primary total hip arthroplasty (THA). Patients and methods — We conducted a cross-sectional study with patients registered in the Danish Hip Arthroplasty Register from 2010 to 2014. Dislocations were captured based on diagnosis/procedure codes and patient file reviews. Patients with dislocation were matched 1:2, according to age, sex, date, and hospital of primary surgery, to patients without dislocation. 2 PRO questionnaires were applied (EQ-5D, HOOS). Results — We identified 1,010 living patients with dislocation. Mean follow-up was 7.2 years from index surgery and 4.9 years (range 0.6–9.7) from the latest dislocation. Patients without dislocation reported a higher EQ VAS score of 76 (95% CI 75–77) compared with 68 (CI 66–70) for the dislocation group. The EQ-5D-5L mean index score was 0.89 (CI 0.88–0.90) for the control group, compared with 0.78 (CI 0.76–0.80) for the cases with dislocation without revision. Patients with dislocation reported a lower HOOS-QoL domain score of 63 (CI 60–65), compared with 83 (CI 82–84) for the control group. Even 5 years after the latest dislocation, the HOOS-QoL score remained low, at 66 (CI 62–69). The other HOOS domains were consistently 8–10 points worse after dislocation. Interpretation — Both health- and hip-related QoL were markedly and persistently reduced among dislocation patients compared with those in controls, for several years. Therefore, the avoidance of the initial dislocation episode is important because the THA does not appear to achieve the full relieving potential.

Dynamic versus static cast immobilization in children aged 6 to 24 months with developmental dysplasia of the hip treated by closed reduction.

The aim of this study was to compare the effects of two types of cast immobilization (human position cast and dynamic cast) on hip development in children with Developmental dysplasia of the hip (DDH) after closed reduction (CR). A retrospective study of 60 children (64 hips) with DDH who underwent CR and cast immobilization between January 2015 and December 2016 at our Institution was performed. The average age at the time of CR was 14.6 months (range, 6.1-23.5). Fifty-seven females and 3 males were included. According to the technique of cast immobilization, two groups of patients could be identified: patients with DDH managed by human position cast immobilization (group A: 32 patients, 34 hips) and patients with DDH treated by dynamic cast immobilization (group B: 28 patients, 30 hips). Hip joint distance (HJD) after CR was measured on MRI. Acetabular Index (AI) and Acetabular Depth Radio (ADR) were measured of anterior-posterior (AP) radiographs before and 3 months after CR; AI and central edge angle (CEA) were measured last follow-up AP radiographs. The presence of subluxation or dislocation and avascular necrosis (AVN) at the last follow-up visit was also evaluated. The patients were comparable regarding to sex, side, age, Tönnis degree, AI, and ADR before the reduction between two groups. There was no significant difference in HJD improvement between the two groups 6 weeks following closed reduction. The AI (27.5±5.1°) of group B was significantly lower than those of group A (31±4.9°) (P=0.03) when cast was removed 3 months after CR. At the last follow-up, the incidence of AVN was similar between the two groups of patients (group A: 11.8% versus group B: 13.3%), and the incidence of subluxation or dislocation (group A: 8.8% versus group B: 10%). At last follow-up visit, the AI (23.7±5.4°) in group B was significantly lower than in group A (26.9±4.1°) (P=0.02). Dynamic cast immobilization promotes acetabular development following CR in patients aged 6 to 24 months with DDH. Dynamic cast immobilization does not increase the risk of dislocation or subluxation, nor of AVN.

Shearing mechanisms of co-precipitates in IN718

The Ni-base superalloy 718 is the most widely used material for turbomachinery in the aerospace industry and land-based turbines. Although the relationship between processing and the resulting properties is well known, an understanding of the specific deformation mechanisms activated across its application temperature range is required to create more mechanistically accurate property models. Direct atomic-scale imaging observations with high angle annular dark-field scanning transmission electron microscopy, complemented by phase-field modeling informed by generalized stacking fault surface calculations using density functional theory, were employed to understand the shear process of γ″ and γ′/γ″ co-precipitates after 1% macroscopic strain at lower temperature (ambient and 427 °C). Experimentally, intrinsic stacking faults were observed in the γ″, whereas the γ′ was found to exhibit anti-phase boundaries or superlattice intrinsic stacking faults. Additionally, the atomically flat γ′/γ″ interfaces in the co-precipitates were found to exhibit offsets after shearing, which can be used as tracers for the deformation events. Phase-field modeling shows that the developing fault-structure is dependent on the direction of the Burgers vector of the a2〈110〉 matrix dislocation (or dislocation group) due to the lower crystal symmetry of the γ″ phase. The interplay between γ′ and γ″ phases results in unique deformation pathways of the co-precipitate and increases the shear resistance. Consistent with the experimental observations, the simulation results indicate that complex shearing mechanisms are active in the low-temperature deformation regime and that multiple a2〈110〉 dislocations of non-parallel Burgers vectors may be active on the same slip plane.

Assessment of knee flexor muscles strength in patients with patellar instability and its clinical implications for the non-surgical treatment of patients after first patellar dislocation - pilot study

BackgroundBiomechanical studies indicate that during outward rotation of the tibia and the valgus knee joint position, the patella is shifted in the lateral direction. After first-time patellar dislocation, the dynamic position of the femur in relation to the tibia plays an important role in joint stability, because the medial stabilizer of the patella (mostly the MPFL) is damaged or inefficient. The most important factor in controlling the rotational movement of the tibia in relation to the thigh are the hamstring muscles. The aim of the study therefore is to determine whether patients with patellar instability have a significant weakness in the knee flexor muscles, which can predispose to recurrent dislocations. This is an important consideration when planning the rehabilitation of patients with first-time patellar dislocation.MethodsThe study enrolled 33 patients with confirmed recurrent patellar dislocation, including six patients with bilateral involvement. In the study group, the hamstring muscles (both sides) were evaluated at velocities of 60 and 180 deg/s for the following parameters: peak torque, torque at 30 degrees of knee flexion, angle of peak torque and peak torque hamstring to quadriceps ratio (H/Q ratio).ResultsIn the recurrent patellar dislocation group, a statistically significant weakness in knee flexors was observed for both angular velocities compared to age and gender normative data. No such relationship was observed in the control group of heathy subjects. In patients with one-sided dislocation, no differences were found in knee flexors peak torque, torque at 30 degrees of knee flexion, angle of peak torque or H/Q ratio between the healthy and affected limbs for either angular velocity.ConclusionsIn patients with recurrent patellar dislocation, knee flexors strength is decreased significantly in both the unaffected and affected limbs. This may indicate a constitutional weakening of these muscles which can predispose to recurrent dislocations.Trial registrationThe study was retrospectively registered on ClinicalTrials.gov (NCT04838158), date of registration; 22/03/2021.

The microstructures and mechanical properties of martensite Ti and TiN phases in a Ti6Al4V laser-assisted nitriding layer

A fiber laser assisted the preparation of a nitride layer on the Ti6Al4V surface in a pure nitrogen atmosphere. Through SEM, XRD, and XPS analyses, the nitride layer is found to be mainly composed of dendritic TiN phase and an interdendritic α′-Ti phase. Not only the true crystal structure of the two main phases (TiN and α′-Ti) were directly characterized using TEM, but also the mechanical properties were tested by micro-indentation and nano-indentation methods for the first time.It is found that the nano-hardness of the TiN phase is 2609 HV, and the elastic modulus is 208 GPa. During the TiN dendritic fracture process, the primary dendrites undergo near ductile fracture along the growth direction of the secondary dendrites, and microcracks, bifurcations, deflection, etc. occur to form a crack-toughening mechanism. The nano-hardness of α′-Ti is 632 HV, and the elastic modulus is 142.8 GPa. The entanglement of two sets of parallel dislocations in α′-Ti crystals forms subgrain boundaries, which exert a positive influence on work hardening and fine-grain strengthening. • A large number of parallel dislocation groups in the generated TiN. • TiN dendrites not only have near ductile fracture, but also have crack toughening; • A large number of parallel dislocation groups and subgrain boundaries in the α′-Ti.

Head-neck movement may predispose to the development of arytenoid dislocation in the intubated patient: a 5-year retrospective single-center study

BackgroundArytenoid dislocation is a rare laryngeal injury that may follow endotracheal intubation. We aimed to determine the incidence and risk factors for arytenoid dislocation after surgery under general anaesthesia.MethodsWe reviewed the medical records of patients who underwent operation under general anaesthesia with endotracheal intubation from January 2014 to December 2018. Patients were divided into the non-dislocation and dislocation groups depending on the presence or absence of arytenoid dislocation. Patient, anaesthetic, and surgical factors associated with arytenoid dislocation were determined using Poisson regression analysis.ResultsAmong the 25,538 patients enrolled, 33 (0.13%) had arytenoid dislocation, with higher incidence after anterior neck and brain surgery. Patients in the dislocation group were younger (52.6 ± 14.4 vs 58.2 ± 14.2 yrs, P = 0.025), more likely to be female (78.8 vs 56.5%, P = 0.014), and more likely to be intubated by a first-year anaesthesia resident (33.3 vs 18.5%, P = 0.048) compared to those in the non-dislocation group. Patient positions during surgery were significantly different between the groups (P = 0.000). Multivariable Poisson regression identified head-neck positioning (incidence rate ratio [IRR], 3.10; 95% confidence interval [CI], 1.50–6.25, P = 0.002), endotracheal intubation by a first-year anaesthesia resident (IRR, 2.30; 95% CI, 1.07–4.64, P = 0.024), and female (IRR, 3.05; 95% CI, 1.38–7.73, P = 0.010) as risk factors for arytenoid dislocation.ConclusionThis study showed that the incidence of arytenoid dislocation was 0.13%, and that head-neck positioning during surgery, less anaesthetist experience, and female were significantly associated with arytenoid dislocation in patients who underwent surgeries under general anaesthesia with endotracheal intubation.

Ultrasonographic prevalence of ulnar nerve displacement at the elbow in young baseball players.

Overhead-throwing athletes are at risk of elbow injury because of valgus stress, leading to unstable ulnar nerves and neuropathy. Studies regarding ulnar nerve damage/displacement have been performed primarily in adults. To determine the prevalence and related factors associated with ulnar nerve displacement at the elbow in young baseball players. Cross-sectional study. Youth baseball players ages 10-12 years were eligible to participate. Exclusion criteria were history of neuropathic pain, trauma, or prior surgery of the upper limb. Fifty-seven participants were eligible for inclusion in the study. Demographic data and ultrasonography findings of ulnar nerve dynamics at the cubital tunnel were analyzed in a total of 114 elbows. Elbows were grouped into nondislocation and displacement (subluxation or dislocation) groups according to ultrasound findings. Logistic generalized estimating equations were used to identify factors associated with ulnar nerve displacement. Thirty-six (31.6%) elbows demonstrated sonographic findings of ulnar nerve displacement, with 13 (11.4%) subluxations and 23 (20.2%) dislocations. Fourteen (24.6%) participants experienced nerve displacement in the dominant elbow only, whereas nerve displacement in both elbows occurred in 11 (19.3%) participants. Nerve displacement in the nondominant elbow only was not observed. Hand dominance and tenderness of the arcade of Struthers' were factors associated with ulnar nerve displacement (odds ratio, 2.81, and 9.73; 95% confidence interval, 1.34-5.91 and 2.45-38.68; p=.006 and .001, respectively). One-third of the young baseball players evaluated had ultrasonographic findings compatible with ulnar nerve displacement at the elbow. Hand dominance and tenderness of Struthers arcade were the only factors associated with ulnar nerve displacement. Ultrasound may help identify patients with ulnar nerve displacement and contribute to the understanding of its pathophysiology in young baseball players.

Etiology of Cartilage Lesions Does Not Affect Clinical Outcomes of Patellofemoral Autologous Chondrocyte Implantation.

To determine the relationship between cartilage lesion etiology and clinical outcomes after second-generation autologous chondrocyte implantation (ACI) in the patellofemoral joint (PFJ) with a minimum of 2 years' follow-up. A retrospective review of all patients that underwent ACI in the PFJ by a single surgeon was performed. Seventy-two patients with a mean follow-up of 4.2 ± 2.0 years were enrolled in this study and were stratified into 3 groups based on the etiology of PFJ cartilage lesions: patellar dislocation (group 1; n = 23); nontraumatic lesions, including chondromalacia, osteochondritis dissecans, and degenerative defects (group 2; n = 28); and other posttraumatic lesions besides patellar dislocations (group 3; n = 21). Patient's mean age was 29.6 ± 8.7 years. Patients in group 1 were significantly younger (25.4 ± 7.9 years) than group 2 (31.7 ± 9.6 years; P = 0.025) and group 3 (31.5 ± 6.6 years; P = 0.05). Body mass index averaged 26.2 ± 4.3 kg/m2, with a significant difference between group 1 (24.4 ± 3.2 kg/m2) and group 3 (28.7 ± 4.5 kg/m2; P = 0.005). A clinical comparison was established between groups based on patient-reported outcome measures (PROMs) and failure rates. Neither pre- nor postoperative PROMs differed between groups (P > 0.05). No difference was seen in survivorship between groups (95.7% vs. 82.2% vs. 90.5%, P > 0.05). Cartilage lesion etiology did not influence clinical outcome in this retrospective study after second generation ACI in the PFJ. Level III, retrospective comparative study.

The dislocation structure of slip bands in deformed high entropy alloy nanopillars

• Slip bands formed in compressed Al 0.1 CoCrFeNi nanopillars are examined by TEM. • A slip band consists primary and secondary dislocations with the latter mostly behind the slip band. • The role of dislocation pileup in front of the slip band is discussed. • A slip band model is proposed based on browns ellipsoidal slip band with supporting evidence of dislocation dipoles. Remarkable diversity is observed in dislocation interactions that are responsible for intermittent and sudden crystal slips. While large crystal slips can be easily observed on the surface of deformed crystals, unraveling the underlying dislocation interaction mechanisms, however, has been a longstanding challenge in the study of single-crystal plasticity. A recent study demonstrated that the sluggish dislocation dynamics in the high entropy alloy (HEA) of Al 0.1 CoCrFeNi enables the observation of slip bands for a direct link to dislocation avalanches in a nanopillar. Here, we further examined the dislocation structure of slip bands in the HEA nanopillars oriented for single slip. Experimental evidence was provided on the dislocation organization in a slip band based on groups of primary dislocations, secondary dislocations, and dislocation pileups. The results were compared with the previously proposed slip band models. The unique aspects of the HEA that enable such observations were also investigated through an examination of the dislocation microstructure and its response to applied forces in the HEA nanopillars.

Bipolar Bone Defects in Shoulders With Primary Instability: Dislocation Versus Subluxation.

Background:In shoulders with traumatic anterior instability, a bipolar bone defect has been recognized as an important indicator of the prognosis.Purpose:To investigate bipolar bone defects at primary instability and compare the difference between dislocation and subluxation.Study Design:Cohort study; Level of evidence, 3.Methods:There were 156 shoulders (156 patients) including 91 shoulders with dislocation and 65 shoulders with subluxation. Glenoid defects and Hill-Sachs lesions were classified into 5 size categories on 3-dimensional computed tomography (CT) scans and were allocated scores ranging from 0 (no defect) to 4 points (very large defect). To assess the combined size of the glenoid defect and Hill-Sachs lesion, the scores for both lesions were summed (range, 0-8 points). Patients in the dislocation and subluxation groups were compared regarding the prevalence of a glenoid defect, a bone fragment of bony Bankart lesion, a Hill-Sachs lesion, a bipolar bone defect, and an off-track Hill-Sachs lesion. Then, the combined size of the bipolar bone defects was compared between the dislocation and subluxation groups and among patients stratified by age at the time of CT scanning (<20, 20-29, and ≥30 years).Results:Hill-Sachs lesions were observed more frequently in the dislocation group (75.8%) compared with the subluxation group (27.7%; P < .001), whereas the prevalence of glenoid defects was not significantly different between groups (36.3% vs 29.2%, respectively; P = .393). The combined defect size was significantly larger in the dislocation versus subluxation group (mean ± SD combined defect score, 2.1 ± 1.6 vs 0.8 ± 0.9 points, respectively; P < .001) due to a larger Hill-Sachs lesion at dislocation than subluxation (glenoid defect score, 0.5 ± 0.9 vs 0.3 ± 0.6 points [P = .112]; Hill-Sachs lesion score, 1.6 ± 1.2 vs 0.4 ± 0.7 points [P < .001]). Combined defect size was larger in older patients than younger patients in the setting of dislocation (combined defect score, <20 years, 1.6 ± 1.2 points; 20-29 years, 1.9 ± 1.5 points; ≥30 years, 3.4 ± 1.6 points; P < .001) but was not different in the setting of subluxation (0.8 ± 1.0, 0.7 ± 0.9, and 0.8 ± 0.8 points, respectively; P = .885). An off-track Hill-Sachs lesion was observed in 2 older patients with dislocation but was not observed in shoulders with subluxation.Conclusion:The bipolar bone defect was significantly more frequent, and the combined size was greater in shoulders with primary dislocation and in older patients (≥30 years).

What are the patient-reported outcomes, functional limitations, and complications after lesser tuberosity fractures? a systematic review of 172 patients.

BackgroundLesser tuberosity fractures are relatively rare, with an incidence of 0.46 per 100,000 persons per year. This systematic review was performed to address patient-reported outcomes (PROMs), shoulder function, and complications after lesser tuberosity fractures in pediatric and adult patients, as well as patients with an associated posterior shoulder dislocation. Within these groups, identical outcomes were evaluated for nonoperative, surgical, acute and delayed treatment.MethodA comprehensive search was carried out in multiple databases. Articles were included if patients sustained a lesser tuberosity fracture without a concomitant proximal humerus fracture. There were no restrictions on age, type of treatment, fragment displacement, time to presentation, or associated injuries.ResultsOne thousand six hundred forty-four records were screened for eligibility of which 71 studies were included (n = 172). Surgical treatment was provided to 50 of 62 (81%) pediatric patients, 49 of 66 (74%) adults, and 34 of 44 (77%) patients with an associated posterior shoulder dislocation. In the pediatric group, the mean of PROMs was 94 (range 70-100) and among adults 89 (range 85-100). In the posterior shoulder dislocation group, 89% did not regain full range of motion and the complication rate was 17%. In pediatric patients, surgery was associated with fewer complications (P = .021) compared to nonoperative treatment.ConclusionPediatric patients have excellent outcomes after lesser tuberosity fractures and respond well to surgical treatment. Adults have acceptable outcomes but patients with an associated posterior shoulder dislocation have impaired range of shoulder movement and are more likely to develop complications.