Dislocation Group Research Articles

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.

Effect of Tensile Deformation on Residual Stress of GH4169 Alloy.

In order to reduce the residual stress of the GH4169 alloy, the effect and micro-mechanism of the tensile deformation were studied. The residual stress, dislocation density, and distribution of the GH4169 alloy were analyzed by X-ray residual stress tester, X-ray diffractometer (XRD), and electron backscatter diffraction (EBSD). The results show that: with the increase of tensile deformation, the residual stress relief first increases and then decreases. When the tensile deformation is 3%, the reduction rate of residual stress reaches the maximum, which is 90%. The mechanism of residual stress relief by the tensile treatment is that the dislocation group in the alloy is activated by tensile treatment, and the dislocation distribution in the alloy is more uniform by dislocation movement, multiplication, and annihilation so that the residual stress can be eliminated.

Experimental evaluation of loading mode effect on plasticity of microscale single-crystal copper

Abstract This study aims to experimentally elucidate the effect of loading mode on plastic behavior of microscale single-crystal copper. Tensile and bending tests involving in situ observations in a scanning electron microscope are carried out by fabricating dog-bone shaped specimens and cantilever beams, respectively, with the same size (2 μm) and the same single-slip orientation. The experimental results show that for microscale single-crystal copper the maximum stress at global failure under bending (288 MPa) is much higher than that of tension (82 MPa), while the yield stress at which the first group of dislocations are generated is similar for both tension (76 MPa) and bending (69 MPa). For tensile tests, the stress increases linearly and monotonically before yielding. The dislocations go through the tensile specimen and synchronously form surface steps at two opposite sides. However, the slip lines in bending specimens are initiated from the surface edges and terminated somewhere inside, and these local strain bursts lead to several intermittent stress drops. Assuming dislocation pile-up mechanism inside of bending specimens, the pile-up stress in the bending is evaluated as about 200 MPa, which agrees well with the experimental results.

Novel method for diagnosing lateral patellar compression syndrome using X-ray: a retrospective case-control study.

BackgroundA well-established reference is lacking for diagnosing lateral patellar compression syndrome (LPCS), and this diagnosis currently depends on clinicians’ subjective judgment and several examination results. X-rays are primarily used to diagnose LPCS, but they have low detection rates of patellar tilt using the congruence angle (CA) and patellar tilting angle (PTA).MethodsWe enrolled 87 patients (31 men and 56 women; mean age: 42.11±15.33 years) between 2016 and 2019 and divided them as per diagnosis into three groups of 29 each: LPCS, patellar dislocation (PD, control), and meniscus tear (MT, negative control) groups. A senior radiologist and the chief physician of sports medicine examined their patellar axial radiographs of the knee in 30° flexion using a computer imaging system, measuring LPCA, CA and PTA. Univariate analysis of variance and Kruskal-Wallis H test were used to compare measurement data with normal distribution and non-normal distribution, respectively. Bonferroni correction was used to analyze different indicators for different groups. The area under the curve (AUC) was calculated to verify the value of LPCA in the initial diagnosis of LPCS.ResultsLPCA (19.88±7.49) was significantly higher in LPCS group than in MT (13.68±4.69) and PD groups (10.16±4.43) (P<0.01) and was also significantly higher on affected side than on healthy side (16.44±5.00) (P=0.04). LPCA >13.9° had sensitivity and specificity of 89.66% and 68.97%, respectively, for LPCS diagnosis (AUC: 0.82, 95% confidence interval: 0.719–0.891, P<0.001).ConclusionsWe demonstrated that LPCA measured using an axial patellar radiograph of the knee in 30° flexion is high in patients with LPCS, and it may be used for diagnosing LPCS.

To Explore the Changes and Differences of Microstructure of Vocal Fold in Vocal Fold Paralysis and Cricoarytenoid Joint Dislocation by Diffusion Tensor Imaging

The diffusion characteristics of water molecules were measured in the vocal folds of canines exhibiting unilateral vocal fold paralysis and unilateral cricoarytenoid joint dislocation. These characteristics were used in conjunction with a histological examination of the microstructural changes of vocal fold muscle fibers to explore the feasibility of diffusion tensor imaging (DTI) in distinguishing unilateral vocal fold paralysis and unilateral cricoarytenoid joint dislocation as well as evaluating microstructural changes. Ten beagles were randomly divided into three groups: four in the unilateral vocal fold paralysis group, four in the unilateral cricoarytenoid joint dislocation group, and two in the normal group. Unilateral recurrent laryngeal nerve resection was performed in the vocal fold paralysis group. Unilateral cricoarytenoid joint dislocation surgery was performed in the dislocation group. No intervention was performed in the normal group. Four months postintervention, the larynges were excised and put into a magnetic resonance imaging (MRI) system (9.4T BioSpec MRI, Bruker, German) for scanning, followed by an analysis of diffusion parameters among the different groups for statistical significance. After MRI scanning, the vocal folds were cut into sections, stained with hematoxylin and eosin, and scanned digitally. The mean cross-sectional area of muscle fibers, and the mean diameter of muscle fibers in the vocal folds were calculated by target detection and extraction technology. Mean values of each measurement were used to compare the differences among the three groups. Pearson correlation analysis was performed on the DTI parameters and the results from histological section extraction. The paralysis group had significantly higher Fractional Anisotropy (FA) compared to the dislocation group and normal group (P=0.004). The paralysis group also had a significantly lower Tensor Trace value compared to the dislocation group and normal group (P=0.000). The average cross-sectional area of vocal fold muscle fibers in the paralysis group was significantly smaller than the dislocation group and normal group (P=0.000). Pearson correlation analysis yielded values of, r=-0.785, P=0.01 between the average cross-sectional area of vocal muscle fibers and FA, and values of r=0.881, P=0.00 between Tensor Trace and the average cross-sectional area of vocal muscle. FA and Tensor Trace can be used as effective parameters to reflect the changes of microstructure in vocal fold paralysis and cricoarytenoid joint dislocation. DTI is an objective and quantitative method to effectively evaluate unilateral vocal fold paralysis and unilateral cricoarytenoid joint dislocation, also capable of noninvasively evaluating vocal fold muscle fiber microstructure.

Theory of particle transport phenomena during fatigue and time-dependent fracture of materials based on mesoscale dynamics and their practical applications.

In this work, the mesoscale mechanics of metals, which links their microscopic physics and macroscopic mechanics, was established. For practical applications, the laws for quantitatively predicting life of cycle and time-dependent fracture behavior such as fatigue, hydrogen embrittlement, and high-temperature creep were derived using particle transport phenomena theories such as dislocation group dynamics, hydrogen diffusion, and vacancy diffusion. Furthermore, these concepts were also applied for estimating the degree of viscoelastic deterioration of blood vessel walls, which is dominated by a time-dependent mechanism, and for the diagnosis of aneurysm accompanied by the viscoelastic deterioration of the blood vessel wall. In these theories, new mechanical indexes were derived as dominant factors for predicting the life of fatigue crack growth and the time-dependent fracture of notched specimens of materials such as hydrogen embrittlement and high-temperature creep. Furthermore, as an example of a practical application, these theories were applied to estimate the degree of viscoelastic deterioration and chaotic motions of blood vessel walls, which are closely related to blood vessel diseases such as atherosclerosis and aneurysm. Moreover, new indexes to diagnose them were also proposed for clinical applications.

Should we employ preoperative templating in hip hemiarthroplasty after femoral neck fracture? A nested case-control study.

Dislocation following hip hemiarthroplasty is a serious complication. It remains unclear if acetabular morphology is associated with a higher risk of dislocation. The aim of our study was to investigate whether there are differences in hip morphology radiological parameters between patients who have suffered a dislocation episode, and those who have not suffered a dislocation. Between January 2015 and December 2018, a nested case-control study was performed. From 707 patients who underwent hip hemiarthroplasty because of femoral neck fracture, 50 patients (50 hips) suffered an episode of dislocation. They were randomly matched with 94 patients (100 hips) without dislocation (ratio 1:2). Clinical data regarding demographics, medical comorbidities and surgical and radiological parameters were studied. Statistically significantly smaller lateral centre-edge angle (LCEA) and femoral offset (FO) and greater Tönnis angle were found in the dislocation group. No differences in acetabular angle were seen. Neurological impairment prevalence was statistically significantly higher in patients who suffered a dislocation (60% vs. 44%, p = 0.011). The current study suggests that a smaller LCEA and FO, a greater TA, and neurological impairment could be related to a higher risk of hip hemiarthroplasty dislocation after femoral neck fracture in the elderly. We consider that preoperative templating could be helpful in identifying abnormal parameters and carefully planning surgery could lead to changes in treatment strategy, such as choosing a dual-mobility total hip arthroplasty.

Subsurface defect evolution and crystal-structure transformation of single-crystal copper in nanoscale combined machining

ABSTRACT In the paper, molecular dynamics simulation is applied to study the evolution and distribution of subsurface defects during nanoscale machining process of single-crystal copper. The chip-removal mechanism and the machined-surface-generative mechanism are examined through analysis of the dislocation evolution and atomic migration of the workpieces. The findings show that under different stresses and temperatures, the difference of the binding energy leads to a zoned phenomenon in the chip. Owing to elastic deformation, some of the dislocations could be recovered and form surface steps; moreover, the work hardening of the workpiece can be achieved on account of generation of twin boundaries, Lomer-Cottrell dislocations, and stacking fault tetrahedra (SFT) by plastic deformation. A process of evolution of an immobile dislocation group containing stair-rod dislocations into SFT is discovered, which is different from the traditional Silcox-Hirsch mechanism. Furthermore, a growth oscillation phenomenon, which corresponding stacking fault planes growth and retraction during the formation of the stable SFT, is discussed.

Evaluation of Dislocation Risk Factors With Total Hip Arthroplasty in Developmental Hip Dysplasia Patients: A Multivariate Analysis

BackgroundThis study aimed to investigate the risk factors for dislocation in patients diagnosed with developmental dysplasia of the hip (DDH) who underwent total hip arthroplasty. MethodsWe retrospectively reviewed 40 patients who developed dislocation and compared them with 400 patients in the control group without hip instability. Patients-, surgery-, and implant-related factors were investigated. Risk factors were evaluated using multivariate logistic regression. ResultsThe mean follow-up period was 32.3 months. The mean time to dislocation was 4.4 months. There were 7 men (17.5%) and 33 women (82.5%) in the dislocation group and 83 men (20.7%) and 317 women (79.3%) in the control group (P = .627). Diabetes mellitus (DM; P = .032) and history of previous hip surgery for DDH were associated with dislocation (P < .001). The subtrochanteric shortening osteotomy (P = .001), acetabular inclination (P = .037), acetabular anteversion (P < .001), femoral head size (P < .001), and postoperative infection (P = .003) were associated with dislocation. Major predictors of hip dislocation after total hip arthroplasty in patients with DDH were previous hip surgery (odds ratio [OR], 6.76; 95% confidence interval [CI], 1.86-24.6; P = .004), high hip center (OR, 2.90; 95% CI, 1.31-6.38; P = .008), DM (OR, 2.68; 95% CI, 1.06-6.80; P = .037), and acetabular inclination (OR, 2.62; 95% CI, 1.09-6.26; P = .03). ConclusionPatients with DM and previous hip surgery should be informed about increased dislocation rates. Using a larger head diameter and restoration of the true hip rotation center are essential to prevent hip dislocation in these patients. Furthermore, accurate positioning of the acetabular inclination and anteversion are also important.

Posterior segment Intra-Ocular Implant (IOL) dislocation: Predisposing factors, surgical management, outcome analysis

To evaluate the predisposing factors, management and visual prognosis of intraocular Lens (IOL) dislocation into the posterior segment. The cases of posterior IOL dislocation from January 2012 to May 2017 at 2 centers were reviewed. Only eyes with dislocations requiring IOL explantation or repositioning were included. Predisposing factors, interval between cataract surgery and IOL dislocation, circumstances of onset, management, and postoperative complications are reported. 72 eyes of 72patients were included. The mean age was 67.6years. 47patients (68%) were men. The mean time interval from cataract surgery to IOL dislocation was significantly shorter in the out-of-the bag group than the in-the-bag IOL dislocation group (3.8 months vs 132 months, P=0.002). Predisposing factors for out-of-the-bag IOL dislocation were mainly capsular rupture and/or zonular dehiscence (83%) after complicated cataract surgery. The predisposing factors for in-the-bag IOL dislocation were high myopia (40%), pseudoexfoliation syndrome (40%), previous vitrectomy (38%), or Marfan syndrome (3%) with uneventful cataract surgery. The type of luxated implant was mainly a 3-piece foldable IOL (50%), followed by foldable one-piece IOL (28%) and a rigid one-piece IOL (17%). Most cases of posterior chamber IOL dislocation occurred spontaneously (80%) without a trigger event. Management consisted of a posterior approach in 24 cases (33%) or an anterior approach in 48 cases (67%), associated with IOL repositioning in 20 eyes (28%), and IOL replacement in 34 eyes (47%). Finally, 18 eyes (25%) were left aphakic. Postoperative complications occurred in 7 cases (9.7%). Predisposing factors and time from cataract surgery to IOL dislocation were different for out-of-the bag versus in-the-bag IOL dislocation. Management of IOL dislocation varied considerably, depending on surgeon preference and experience. Surgery for IOL dislocation significantly improved best corrected visual acuity and was associated with a low complication rate.

Difference Between Posterior Monteggia Fractures and Posterior Fracture-Dislocation of Proximal Ulna in Adults.

ObjectiveTo figure out the difference between patients with posterior Monteggia fractures which were concomitant with proximal radioulnar joint (PRUJ) dislocation and posterior fracture‐dislocation of the proximal ulna that were not concomitant with PRUJ.MethodsFrom January 2016 to January 2019, 37 consecutive adult patients who had posterior fracture‐dislocation of proximal ulna (no PRUJ dislocation, n = 16) and posterior Monteggia fractures (PRUJ dislocation, n = 21) were included. All patients had intraoperative fluoroscopy, computed tomography (CT) scans, and standard radiography (anteroposterior view and lateral view). The mechanism of injury, the cases with open fracture, sustained multiple injuries and classification of fracture was recorded. The clinical details of the patients such as the final range of motion (ROM) and the Broberg–Morrey scores were described.ResultsPatients with PRUJ dislocation (ten type A, five type B, and six type D) and those without concomitant PRUJ dislocation (fifteen type A and one type C) exhibited an obvious difference according to the classifications of Jupiter et al. (P = 0.010). Ninety‐five percent of patients who had PRUJ dislocation were accompanied by a metaphyseal fracture, while only 50% of the patients who did not have PRUJ dislocation were accompanied by a metaphyseal fracture (P = 0.002). Meanwhile, 16 of 20 metaphyseal fractures had more than one fragment in the group of dislocations, but five of eight metaphyseal fractures were comminuted in the control group. The two groups exhibited an obvious difference (P = 0.009). The 21 patients who sustained a radioulnar dislocation had less mean arc of flexion, pronation, and Broberg–Morrey scores were significantly less than the patients of the control group (flexion: 117.38 ± 14.46 vs 127.50 ± 13.416, P = 0.035; pronation: 59.76 ± 11.88 vs 67.50 ± 6.58, P = 0.017; Broberg–Morrey: 80.48 ± 12.17 vs 88.19 ± 10.28, P = 0.040).ConclusionsPatients suffering posterior Monteggia fractures had more metaphyseal fractures, more comminuted fractures of the metaphysis, and worse ultimate ulnohumeral motion than patients of posterior fracture‐dislocation of proximal ulna.

Holistic Approach on the Research of Yielding, Creep and Fatigue Crack Growth Rate of Metals Based on Simplified Model of Dislocation Group Dynamics

The simplified model of numerical analyses of discrete dislocation motion and emission from a stressed source was applied to predict the yield stress, dislocation creep, and fatigue crack growth rate of metals dominated by dislocation motion. The results obtained by these numerical analyses enabled us to link various dynamical effects on the yield stress, dislocation creep, and fatigue crack growth rate with the experimental results of macroscopic phenomena, as well as to link them with theoretical results obtained by the concept of static, continuously distributed infinitesimal dislocations for the equilibrium state under low strain or stress rate conditions. This will be useful to holistic research approaches with concern for time and space scales, that is, in a time scale ranging from results under high strain rate condition to those under static or low strain rate condition, and in a space scale ranging from meso-scale to macro-scale mechanics. The originality of results obtained by these analyses were found by deriving the analytical formulations of number of dislocation emitted from a stressed source and a local dynamic stress intensity factor at the pile-up site of dislocations as a function of applied stress or stress rate and temperature material constants. This enabled us to develop the predictive law of yield stress, creep deformation rate, and fatigue crack growth rate of metals dominated by dislocation motion. Especially, yielding phenomena such as the stress rate and grain size dependence of yield stress and the delayed time of yielding were clarified as a holistic phenomenon composed of sequential processes of dislocation release from a solute atom, dislocation group moving, and stress concentration by pile-up at the grain boundary.

Comparison of surgical dislocation and impacting bone graft and surgical dislocation and rotational osteotomy for the treatment of ARCO III femoral head necrosis.

Hip preserving procedures are still a challenge in late-stage osteonecrosis of femoral head (ONFH) patients. We aimed to compare the clinical outcomes of surgical dislocation and impaction bone graft and surgical dislocation and rotational osteotomy for treatment of ONFH in Association Research Circulation Osseous (ARCO) stage III patients.We retrospectively reviewed 30 ARCO stage III patients (33 hips) who had surgical dislocation and impaction bone graft or surgical dislocation and rotational osteotomy in our center from June 2012 to December 2017. Baseline characteristics, clinical evaluation using Harris score and radiologic evaluation up to 12 months after surgery were recorded and compared.Fifteen patients (17 hips) were in the surgical dislocation and impaction bone graft group and 15 patients (16 hips) were in the surgical dislocation and rotational osteotomy group. No significant differences in age, gender, etiology, ARCO stage, duration of illness, operation time, and length of hospitalization were observed between the 2 groups. Compared to preoperation Harris score, the Harris score of 6 months postoperation and 12 months postoperation significantly improved. At 12 months postoperation, the excellent and good rate was 76.5% in the impaction bone graft group and 87.5% in the rotational osteotomy group. No significant difference in Harris scores was detected in the 2 groups.Surgical dislocation and impaction bone graft and surgical dislocation and rotational osteotomy had satisfactory 1-year efficacy for ARCO III ONFH patients. Surgical dislocation and rotational osteotomy had better short-term efficacy than surgical dislocation and impaction bone graft.

Surgical treatment of symptomatic post-slipped capital femoral epiphysis deformity: a comparative study between hip arthroscopy and surgical hip dislocation with or without intertrochanteric osteotomy.

PurposeOur primary research question was to investigate the severity of deformity and articular damage as well as outcomes in patients undergoing hip arthroscopy compared with open surgery for the treatment of symptomatic slipped capital femoral epiphysis (SCFE) deformity.MethodsRetrospective review of surgical treatment of symptomatic SCFE deformity with a minimum one-year follow-up. Patients were divided into three groups: the arthroscopic group, surgical hip dislocation(SHD) group and SHD with femoral osteotomy (SHD+ITO) group. Deformity severity was quantified. Hip outcome was assessed by the modified Merle d’Aubigné Postel (MDP) scores.ResultsThere were more severe slips treated by SHD and SHD+ITO. There was more severe deformity in the SHD+ITO group than the arthroscopy group (p < 0.001). There were more full thickness acetabular cartilage defects in the SHD and the SHD+ITO groups (> 40%) compared with the arthroscopy group (11%; p = 0.03). The SHD+ITO and SHD group had lower MDP scores compared with the arthroscopy group both before and after surgery but no difference was detected in the amount of improvement from surgery across groups (p > 0.05). Moderate and severe SCFEs had worse preoperative scores but improvement was not different compared with mild SCFEs (p > 0.05).ConclusionPatients undergoing open treatment had more severe SCFE deformity with more extensive articular damage at reconstructive surgery compared with patients undergoing arthroscopy. All groups with SCFE deformity had improved pain and hip function postoperatively.Level of EvidenceIII

Risk of Dislocation After Total Hip Arthroplasty in Patients with Crowe Type IV Developmental Dysplasia of the Hip.

ObjectiveTo investigate whether the risk of dislocation after total hip arthroplasty (THA) in patients with Crowe type IV developmental dysplasia of the hip (DDH) is high and to further identify the risk factors for postoperative dislocation in these patients.MethodsThis retrospective cohort study reviewed Crowe type IV DDH patients undergoing THA between January 2009 and December 2017 in our institution. Each Crowe type IV DDH patient was matched with three Crowe type I, II, or III DDH patients according to gender, side and date of operation. The primary outcome of this study was postoperative dislocation after THA. Occurrence, rate, classification, treatment and outcome of dislocation were documented in detail for all patients. The dislocation rates were compared between Crowe type IV DDH patients and Crowe type I, II, or III DDH patients. Demographic data, implant factors, and surgical factors were compared between the dislocation and no dislocation groups. Multiple logistic regression analysis was used to determine the independent risk factors for dislocation in Crowe type IV hips.ResultsA total of 131 Crowe type IV hips were followed up for a mean of 76.5 ± 28.1 months. Three hundred and ninety‐three Crowe type I, II and III hips, including 261 type I hips, 94 type II hips, and 38 type III hips, were identified as controls and followed up for a mean of 76.4 ± 28.2 months. No significant difference was observed in follow‐up time between two groups (P = 0.804). One or more dislocations occurred in 22 of the 524 dysplasia hips (4.20%). Of the 22 dislocated hips, 20 hips (90.9%) were successfully managed with non‐operative treatment. Two patients (9.1%, one Crowe type I and one Crowe type IV) experienced recurrent dislocation and required revision surgery. Crowe type IV hips had a significantly higher postoperative dislocation rate than type I, II, and III hips (11.45% vs 1.78%, P < 0.001). The use of a 22‐mm femoral head (odds ratio [OR] = 23.55, 95% confidence interval [CI] = 1.901–291.788, P = 0.014), older age (OR = 1.128, 95% CI = 1.037–1.275, P = 0.031), and absence of false acetabulum (OR = 12.425, 95% CI = 1.982–77.879, P = 0.007) were identified as independent risk factors for dislocation in Crowe type IV hips.ConclusionsCrowe type IV DDH patients were at a high risk of dislocation after THA, and using large femoral heads and improving abductor muscle strength may help decrease the rate of postoperative dislocation in such patients.

A New Sight of the Growth Characteristics of Solidified Al3Ni at the Liquid–Solid Interface by Synchrotron Radiography and 3D Tomography

The growth mechanisms of single- and variant-flake Al3Ni phases at the liquid Al/solid Ni interface during solidification were investigated by synchrotron radiography and 3D tomography. The single-flake Al3Ni in the form of an elongated diamond rod evolves from one needle-like grain. The variant-flake Al3Ni is formed by coalescence of several needle-like Al3Ni grains, and its growth is dominated by the creation and propagation of a pair or groups of screw dislocations with opposite signs.

Surgical Outcomes In The Frequency, Etiology, Direction, Severity (feds) Classification System For Shoulder Instability

Objectives: The Frequency, Etiology, Direction, Severity (FEDS) system is a reliable and reproducible classification of glenohumeral instability. Frequency is defined as Solitary (1), Occasional (2-5), or Frequent (&gt;5) episodes per year; etiology as Traumatic or Atraumatic; direction as Anterior, Posterior, or Inferior; and severity as a Subluxation or Dislocation. 36 total combinations are possible, named by the first letter of each variable in order. The purpose of this descriptive study was to investigate epidemiology, surgical outcomes, and failure using FEDS in patients undergoing surgery in a large multicenter cohort of prospectively enrolled patients. Methods: 1204 patients undergoing surgery were assigned to FEDS categories. Two-year follow-up at time of analysis was available for 629 patients (85.7% of those eligible based on date of surgery). Those categories consisting of at least 5% of patients were further analyzed by patient reported outcomes (PROs) and failure rates for a total of 466 patients. PROs included American Shoulder and Elbow Surgeons score (ASES), Western Ontario Shoulder Instability index (WOSI), and Single Assessment Numeric Evaluation (SANE). Failure benchmarks included rates of recurrent subluxation, dislocation, and revision surgery. Results: Sixteen categories represented at least one percent of patients. Occasional Traumatic Anterior Dislocation (OTAD) was the most common category with 16.4% of patients. Five other anterior categories (STAS, OTAS, FTAS, STAD, FTAD) and one posterior category (STPS) represented at least 5%. PROs and failure rates for anterior categories are summarized in Figure 1. PROs improved significantly for each category. A downward trend in WOSI and ASES was noted in particular with increasing frequency of the dislocation groups. The highest rates of each type of failure occurred in the occasional and frequent groups for both dislocation and subluxation. Low rates of failure occurred in STPS, with 17.9% reporting subluxation, 3.6% dislocation, and no revisions. Conclusion: While overall success was good, different FEDS categories showed varying degrees of improvement and failure rates, indicating that the system can be used to provide prognostic insight for presurgical education. Overall, outcomes for traumatic anterior instability decreased with higher initial frequency, showing worse PROs and higher failure. Frequency appeared to have the greatest effect on outcomes. Early surgical intervention may be beneficial in preventing progression to more severe FEDS categories, with higher frequency having previously been associated with both higher rates of bone loss and greater time between initial event and surgical stabilization.

Soft tissue injury patterns in posteromedial rotatory instability with dislocation compared with posteromedial dislocation of the elbow joint

We sought to determine injury mechanisms and soft tissue injury patterns of dislocation caused by posteromedial rotatory instability (PMRI) and simple posteromedial (PM) dislocation of the elbow joint that appear similar on simple radiographs. In this retrospective case-series study, we reviewed 13 patients with PMRI dislocation and 10 patients with simple PM dislocation. Three-dimensional computed tomography and magnetic resonance imaging were performed in both groups. The ulnar collateral ligament, lateral collateral ligament complex (LCLC), overlying extensor muscle, and locus of bone contusion were identified. The direction of dislocation was categorized into the pure-posterior or PM type by simple radiographs. The LCLC was completely ruptured in both groups. A completely torn ulnar collateral ligament was observed in 3 patients (23%)in the PMRI dislocation group and 9 patients (90%)in the simple PM dislocation group (P = .005). Regarding injury patterns of the LCLC and overlying extensor muscle, the distraction type was found in 10 patients (77%) and the stripping type was found in 3 patients (23%) in the PMRI dislocation group, whereas all patients (100%) in the simple PM dislocation group had the distraction type (P = .103). Bone contusion was observed at the posterolateral olecranon in 2 patients (15%)in the PMRI dislocation group andat the PM olecranon in 4 patients (40%),posterolateral olecranon in 1 (10%),posterior olecranon in 1 (10%), and PM-posterolateral olecranon in 1 (10%) in the simple PM dislocation group (P = .008). In the PMRI dislocation group, 7 patients (54%) had the PM type and 6 (46%) had the pure-posterior type. Simple PM and PMRI dislocations of the elbow joint might have different soft tissue injury characteristics because of different injury mechanisms.

Factors affecting dislocation after bipolar hemiarthroplasty in patients with femoral neck fracture

PurposeThis study aimed to investigate the anatomic risk factors associated with dislocation following bipolar hemiarthroplasty for the treatment of femoral neck fracture. Materials and MethodsWe retrospectively reviewed 208 consecutive patients (133 women, 75 men) with femoral neck fractures who were treated with bipolar hemiarthroplasty between 2015 and 2018. A comparative analysis was performed between dislocation (n = 18) and non-dislocation (n = 190) groups in terms of patient demographics, surgical and pelvic morphologic factors, and clinical outcomes, including postoperative Harris and modified Harris hip scores. Independent risk factors affecting dislocation were also evaluated. ResultsThe mean follow-up period was 30.8 ± 2.0 (range, 12–48) months. The mean age was 79.2 ± 7.4 (range, 71–94) years. The dislocation rate was 8.6% (18/208), and the mean dislocation time after operation was 2.0 ± 1.1 (range, 1–4) months. Patient-related factors did not differ between the dislocated and non-dislocated groups. As regards dislocation, statistically significant difference was observed in surgical and pelvic morphologic factors, including femoral offset, residual femoral neck length, trochanter upper end and femoral head center distance, and height of the hip center of the operated side (p = 0.025, p = 0.013, p = 0.002, p = 0.008, respectively). Moreover, the femoral offset, height of the hip center, and femoral neck-shaft angle of the non-operated side are significantly different between the groups (p = 0.007, p = 0.001, p = 0.027, respectively). Decrease in the center edge (CE) angle, offset of prosthesis, and increase in femoral head extrusion index (FHEI) of the operated side and decrease in the height of the hip center of the non-operated side increased the risk of dislocation (p = 0.030, OR: 1,306; p = 0.041, OR: 8.15; p = 0.020, OR: 1.038; p = 0.010, OR: 2.02, respectively). ConclusionsPelvic morphologic features and surgical factors were found to affect dislocation. Patients with smaller OP, CE angle of the operated side, and higher FHEI and smaller height of the hip center of the non-operated side should be carefully monitored to decrease postoperative dislocation.

Corrections in alpha angle following two different operative approaches for CAM-type femoral acetabular impingement - Ganz surgical hip dislocation vs anterior mini-open.

BACKGROUNDFemoroacetabular impingement (FAI) is a predisposing factor for secondary osteoarthritis of the hip joint. The two extensively described impingement mechanisms of FAI are CAM and Pincer-type. Initially managed conservatively, operative intervention should be offered to the persistently symptomatic patient. The measurement of the alpha angle is considered a standard method of assessing the severity of pathology in Cam-type FAI on pre-operative plain radiographs. The radiological correction of the alpha angle has not been previously compared between different surgical approaches. We hypothesize that there is no difference in alpha angle correction between Ganz surgical hip dislocation and the anterior mini-open approach.AIMTo compare the magnitude of alpha angle correction achieved by using the Ganz surgical hip dislocation and the anterior mini-open approach.METHODSThis is a retrospective study assessing seventy-nine patients identified in a 5-year period. These patients had preoperative radiographic evidence of FAI and underwent surgery by a single surgeon at our institution, a tertiary care center. Patients with missing radiographic documentation, radiographs with insufficient quality which then precluded accurate measurement of the angle α, a diagnosed congenital condition, isolated type II pathology (Pincer), and history of prior surgery were excluded from the study. Either the Ganz surgical hip dislocation or the anterior mini open approach was used. Postoperative radiographic evaluation of the alpha angle between the two surgical methods was done and corrected for age and gender using two-sample t-tests and Chi-square analyses.RESULTSA total of 79 patients met the inclusion and exclusion criteria. Forty-seven males (mean age of 35.3, range 16-53) and 32 females (mean age 36.7, range 16-60) were enrolled. Forty-seven patients underwent the anterior mini-open approach, and 32 underwent the Ganz surgical hip dislocation. There were no significant differences in age between the two surgical groups or in pre- and post-operative alpha angles based on patient gender. The mean pre-operative alpha angle for the Ganz surgical hip dislocation group was 88.0 degrees (SD 12.3) and 99.4 degrees (SD 7.2) for the anterior mini-open group. Mean post-operative angles were 49.9 degrees (SD 4.3) for the Ganz surgical hip dislocation and 43.8 (SD 4.3) degrees for the anterior mini-open group. There was a statistically significant difference in patient’s pre-operative and post-operative angles (P = 0.000) with both surgical approaches.CONCLUSIONStatistically significant decreases in alpha angle were noted for both surgical techniques, with larger decreases seen in the anterior mini-open group.