Native Position Research Articles

Remote Regulation by VirB, the Transcriptional Anti-Silencer of Shigella Virulence Genes, Provides Mechanistic Information.

Classical models of bacterial transcription show regulators binding close to promoter elements to exert their effect. However, the scope for long-range regulation exists, especially by nucleoid structuring proteins, like H-NS. Here, long-range regulation by VirB, a transcriptional regulator that alleviates H-NS-mediated silencing of key virulence genes in Shigella species, is explored invivo to test the limits of long-range regulation and provide further mechanistic insight. VirB-dependent regulation of the well-characterized icsP promoter persists if its cognate site is repositioned 1 kb, 3.3 kb, and even 4.7 kb further upstream than its native position in a plasmid reporter. VirB-dependent regulation diminishes with binding site distance. While increasing cellular VirB pools elevated promoter activity in all constructs with wild-type VirB binding sites, it did not generate a disproportionate increase in promoter activity from remote sites relative to the native site. Since VirB occludes a constitutively active promoter (PT5) when docked adjacent to its -35 element, we next moved the VirB binding site far outside the promoter region. We discovered that VirB still interfered with promoter activity. These findings and those generated from molecular roadblocks engineered around a distally located VirB-binding site are reconciled with the various models of transcriptional regulation by VirB.

Last place aversion, labour market competition or welfare state model? Explaining anti-immigrant sentiment in Hungary with a conjoint experiment

ABSTRACT Much ink has been spilled to explain how the relative socio-economic position of natives and immigrants might shape anti-immigrant sentiment. However, little effort has been made to pit three competing theories: last place aversion, labour market competition and the welfare state model directly against each other, despite their often-times contradicting implications. This paper tests these alternative theories in Hungary, where the 2015 migration crisis has catapulted a previously hardly salient topic into the forefront of issues on the political agenda. Utilizing a choice-based conjoint experiment, administered on a nationally representative sample of voting-age Hungarians in Spring 2021, aforementioned hypotheses are tested in a country known for its hardline stance on migration. Results suggest fears related to welfare exploits might be the most plausible explanation for widespread anti-immigrant sentiment in the Hungarian public, as the less education fictive refugee profiles showcased, the less likely respondents were to admit them. Contrarily, no evidence corroborating worries associated with labour market competition or last place aversion was found. Future research could explore whether skills mismatch makes natives less wary of labour market competition, as well as the extent to which the 2022 Russian invasion of Ukraine altered Hungarians' attitudes.

An MRI-Derived Formula for Estimating the Native Joint Line Position in the Presence of Distal Femoral Bone Loss.

Background In the presence of distal femoral condyle bone loss, estimation and restoration of the joint line (JL) position can be guided by extraarticular bony landmarks with the aid of mathematical formulas that rely on the innate correlations between periarticular measurements. To prevent JL elevation, the formula should incorporate the thickness of distal femoral articular cartilage. The aim of this study was to derive a formula to estimate native JL position. Methods One hundred and fifty knee magnetic resonance imaging (MRI) studies belonging to 150 patients were chosen from a database of scans. Multiple periarticular measurements were taken. Based on the strongest correlation between measurements, linear regression analysis was used to derive a regression equation to estimate the JL position. This formula was then tested to determine its accuracy and reliability in estimating the JL. Results Using the Pearson correlation test, the strongest correlation was identified to be between adductor tubercle to joint line distance (ATJL) and transepicondylar width (TEW) with r = 0.723, p <.001. Using linear regression analysis, the following regression equation was obtained: ATJL in millimetres = 0.53 (TEW in millimetres) + 2.4mm. This formula estimated the JL within 4 mm of the native JL in 86% of measured knees and within 8 mm in 100% of measured knees. The mean difference between calculated ATJL and measured ATJL was 2.43 mm with a standard deviation of 1.94 mm. Conclusion The current formula (ATJL = 0.53(TEW) + 2.4mm) reliably estimates native JL distance from the adductor tubercle (AT) to within a clinically significant range, using femoral TEW.

Molecular Docking of Nigella Sativa L. with PXR Receptors and the Effect of Thymoquinone on PXR Expression in HepG2 Cells

ABSTRACT. The interaction between herbal remedies and drugs is a fascinating phenomenon that might cause therapeutic complications in patients. Warfarin is an anticoagulant drug that provides anti-blood-clotting effects by inhibiting the formation of vitamin K-dependent coagulation factors, and warfarin interacts with the nuclear receptor PXR, subsequently modulating cytochrome P450 during the metabolism process. St. John's wort, an herbal medicine with antidepressant effects, can alter the pharmacokinetics of warfarin. Thymoquinone is one of the active compounds in N. sativa and has pharmacological activities such as anticoagulant, antidiabetic, diuretic, antidepressant, and anti-inflammatory effects. In this study, we investigated the compounds in Nigella sativa (N. sativa) against pregnane X receptor (PXR) and evaluated the impact of thymoquinone (TQ) administration on PXR expression in HepG2 cells. The molecular docking analysis was conducted utilizing the Molecular Operating Environment (MOE) with the PXR (PDB ID: 7AXJ). At the same time, the PXR gene expression was measured using RT-PCR instruments. The RMSD value in docking represents the deviation criteria between the native ligand position and the redocking position result, indicating the capability of MOE and PDB qualification for performing molecular docking. The docking analysis showed that warfarin had the strongest binding energy (7AXJ -6.0507) by forming hydrogen binding type on Arg410. Despite TQ being the major component, it also displayed a high affinity for the two PDB IDs (7AXJ -4.5962). Furthermore, the concurrent administration of warfarin and TQ (19.27 μM) in HepG2 cells showed a significant reduction in the relative mRNA expression of the PXR gene. Given the above-mentioned findings, our study adequately enables us to predict the mechanism behind herb-drug interactions (HDIs) implicating N. sativa, specifically the TQ compound to warfarin metabolism via the activation of the PXR receptor. Keywords: Thymoquinone, expression mRNA, PXR, molecular docking, HepG2 cells.

Does Patellar Height Influence Range of Motion and Anterior Knee Pain after Distal Femur Endoprosthesis Reconstruction?

Objectives: This study aims to evaluate the patellar height changes after distal femur (DF) endoprosthetic replacement (EPR) and its impact on anterior knee pain (AKP) and range of motion (ROM). Methods: A retrospective review of three institutions' databases was performed. The patellar height was determined using the modified Insall-Salvati ratio (MIS), the Blackburne-Peel (BP) and the Caton-Deschamps (CD) indexes. Data regarding AKP and ROM were collected. Results: A total of 199 patients were included. The mean age at presentation was 37.9 ± 23.1 years. The mean one-year follow-up MIS, BP and CD were 1.52 (sd: 0.41), 0.82 (sd: 0.33) and 0.93 (sd: 0.33). Patellar height decreased significantly compared to the pre-operative values according to all three scores (p < 0.001). AKP was reported by 34 (17.1%) patients at 1 year follow-up. Patients with patella baja (MIS < 1.2) or pseudo patella baja (CD < 0.6) had a higher incidence of AKP (p = 0.037 and p = 0.024, respectively). The mean flexion ROM was 91°, with a direct correlation with patellar height (MIS p = 0.020, BP p = 0.036 and CD p = 0.036). Conclusion: The restoration of the native position of the joint line in DF EPR is important to maintain optimal patellofemoral biomechanics. Despite surgeons' tendency toward a reduction in patellar height with respect to pre-operative values, an increase in patellar height might help to achieve better knee flexion and reduce AKP.

Learners’ Challenges and Problems in English Listening Skill (A study on students at King Faisal University)

The goal of the study is to understand the issues and difficulties King Faisal University students encounter at the Applied College when they are learning English listening skills, as well as the strategies they employ to get past these difficulties. This study is significant because it will shed light on the difficulties that students encounter when learning English listening skills, which will benefit King Faisal University, English language instructors, curriculum designers, and researchers. King Faisal University will be aware of the academic standing of its students and might offer native English speakers positions as English language instructors. In order to determine averages, examine causality, and make broader demographic generalizations, the researcher employed a quantitative technique by applying the random sampling of male and female English 101 and 102 students enrolled in the Applied College at King Faisal University in the second semester of 2024. The study's findings indicate that while Saudi female students have more challenges than their male counterparts, both genders in the country have trouble learning English listening skills. The study's recommendations are based on its findings, which include enhancing listening techniques, giving universities and schools the tools they need to teach English listening skills, and pushing students to raise their proficiency levels in the language.

Highly Regio- and Stereoselective Dehydration of Allylic Alcohols to Conjugated Dienes via 1,4-syn-Elimination with H2 Evolution.

Dehydration of alcohols is one of the most fundamental transformations in the organic chemistry class and one of the most widely used methods for producing alkenes in synthetic research. Numerous methods and reagents have been developed to control the regio- and stereoselectivity as well as the dehydration efficiency of normal alcohols. Despite these achievements, regio- and stereoselective and predictable dehydration of allylic alcohol has seldom been reported, except for limited substrates with a native preferred elimination position, as a result of the challenges that many potential dienes could be formed via 1,2- or 1,4-syn- or anti-elimination. Here, we report a tBuOK/potassium 2,2-difluoroacetate-mediated 1,4-syn-dehydration of allylic alcohol for the synthesis of regio- and stereodefined conjugated dienes via an in situ generated directing group strategy. This reaction exhibits a broad substrate scope and good functional group compatibility for primary-tertiary alcohols. The simple and scalable (up to 0.6 mol) procedure with readily available and inexpensive reagents makes it a practical method for conjugated diene synthesis. Mechanistic studies reveal that an acetate with tert-butoxide and allyloxide acetal moiety is formed as an intermediate, in which the acetate and the acetal act as the directing group for the base-promoted elimination. An unusual H2 evolution is also involved in the reaction.

Nonanatomic femoral tunnel placement increases the risk of subsequent meniscal surgery after ACLR: Part II-Patients without recurrent ACL injury.

The purpose of this study was to identify risk factors for subsequent meniscal surgery following anterior cruciate ligament (ACL) reconstruction (ACLR) in patients without recurrent ACL injury. Patients aged ≥14 years who underwent primary ACLR with minimum 1-year follow-up and without recurrent ACL injury were retrospectively reviewed. Patient demographics and surgical data at the time of ACLR were collected. Postoperative radiographs were used to measure femoral and tibial tunnel position, and posterior tibial slope. Univariate and multivariate analyses were performed to identify risk factors for subsequent meniscal surgery. Of 629 ACLRs that fulfilled the inclusion criteria, subsequent meniscal surgery was performed in 65 [10.3%] patients. Multivariate analysis revealed that medial meniscal repair at the time of ACLR, younger age, anterior femoral tunnel position and distal femoral tunnel position were significantly associated with subsequent meniscal surgery (p < 0.001, p = 0.016, p = 0.015, p = 0.035, respectively). The frequency of femoral tunnel placement >10% outside of the literature-established anatomic position was significantly higher in those who underwent subsequent meniscal surgery compared to those who did not (38.3% vs. 20.3%, p = 0.006). Posterior tibial slope and ACL graft type were not significantly associated with subsequent meniscal surgery. Medial meniscal repair at the time of ACLR, younger age and nonanatomic femoral tunnel placement were risk factors for subsequent meniscal surgery in patients without recurrent ACL injury. Femoral tunnel placement <10% outside of the native anatomic position is important to reduce the risk of subsequent meniscal surgery. Level IV.

Novel positioning guiders accurately assist in situ acetabular reconstruction for patients undergoing pelvic bone tumor resection.

Acetabular reconstruction in situ after extensive pelvic resection is technically challenging. The aim of this study was to investigate the feasibility of positioning guiders for acetabular reconstruction following pelvic tumor resection and the clinical benefit brought by the approach. The study included patients who underwent acetabular reconstruction following periacetabular tumor resection using a modular hemipelvic prosthesis. In the guider-assisted group (n = 14), guiders were designed and applied to assist acetabular reconstruction. In the traditional operation group (n = 18), the patients underwent the same surgery but without the guiders. The displacement of the hip rotation center before and after surgery was calculated. The complications and the Musculoskeletal Tumor Society-93 scores were documented. The overall displacement of the hip rotation center was significantly reduced in the guider-assisted group compared with the traditional operation group (13.83 ± 4.06 vs. 22.95 ± 9.18mm in P = 0.000, 95%CI 3.90-12.96), especially in the anteroposterior axis (3.77 ± 3.03 versus 13.51 ± 9.43mm in P = 0.000, 95%CI 3.45-13.09). Guider-assisted acetabular reconstruction reduced the risk of prosthesis dislocation compared with the traditional operation (dislocation risks: 1/14, 7.1% vs. 4/18, 22.2%). Positioning guiders can effectively and conveniently help place the modular hemipelvic prosthesis at the native position, which might potentially reduce the risk of prosthesis dislocation. Therapeutic level III.

Rethinking peer interaction in language classrooms: students and L1 peers as mediators and experts in higher education

ABSTRACT In today’s multilingual and multicultural societies, different languages and cultural orientations converge for complex purposes. This study examines how Spanish language students and their native peers (L1 peer = L1P) experiment with dynamic and culturally embedded language uses in higher education. The data included conversation recordings between students (N = 17) and L1Ps (N = 2). A qualitative conversation analysis of the student-L1P interaction revealed multiple and shifting learner-expert positions that led to reciprocal intercultural mediation. Both students and L1Ps mediated diverse linguistic and cultural knowledge to each other by relying on a rich array of multimodal mediational means. However, the L1Ps’ role as peers on the students’ level was crucial in fostering communication in the target language beyond native and non-native speaker positions.

A Novel Method for Secondary Mandible Reconstruction to Re-Achieve a Native Condyle Position Comprising a New Design for Cutting Guides and New Positioning Devices.

Secondary mandibular reconstruction using fibular free flaps (FFF) is a technical challenge for surgeons. Appropriate operation planning is crucial for postoperative quality control and is notably necessary for the (re-) achievement of a physiological condylar position, and the sensible expansion and shaping of the transplant. Computer-assisted planning may help to reconstruct mandibular defects in a patient-specific and precise manner. Herein, we present a newly-developed workflow for secondary mandibular reconstruction using FFF; it comprises digital planning and in-house manufacturing to perform precise secondary mandible reconstruction. This method utilizes a newly designed positioning device to ensure the precise positioning of the fibula segments in relation to each other and the mandibular stumps. The presented in-house-printed positioning device made it possible to achieve digital planning with high precision during surgery.

Critical Complete-Member Ethnography Revisited: A Heuristic Reflection of Nativeness, Insiderness, and Homeland During the COVID-19 Pandemic

In this essay, I engage in autoethnographic reflection on my role as a native researcher, addressing questions and issues related to evaluating a researcher’s complete-membership in Critical Complete-Member Ethnography (CCME). I revisit CCME as a critical communication research method and introduce two contextual elements –the geopolitics of transnational mobility and cultural belongingness– to enhance the depth of self-reflection that CCME can encourage researchers to undertake. Specifically, I discuss these two components within the framework of nativeness, as these factors often involve the challenges faced by international researchers when they claim their native or insider position upon returning to their non-Western homelands to conduct ethnography. In my autoethnographic reflection, I draw on my fieldwork experience in South Korea as an instance, focusing on different conditions that destabilized my native position: institutional regulations of crossing the border during the global pandemic, my growing feeling of in-betweenness, and my performance of U.S. academic membership in the field. Through reflection, I demonstrate that nativeness is not consistently given or entitled but changing and fluctuating in different times and contexts. Ultimately, I argue that in-flux aspects of my native position complicate and expand methodological considerations for determining and accessing a researcher’s complete-membership and their epistemological intimacy with their communities in CCME.

Abstract 15472: The IRIS™ Valve: A Growth Accommodating Transcatheter Pulmonary Valve for Pediatric Patients

Introduction: It is estimated that at least 1 million children are living with a congenital heart defect (CHD) in the U.S. Most of these patients are born with some degree of right ventricular outflow tract (RVOT) abnormalities that at some point require pulmonary valve replacement to mitigate the detrimental effects of pulmonary valve regurgitation (PVR) on the right ventricle (RV). Due to their size, available solutions, e.g., the Melody™ valve (Medtronic Inc., Minneapolis, MN) cannot be implanted in small children under 20 Kg. Those must wait until they grow to a suitable weight to receive the valve, which may lead to RV dysfunction. Hypothesis: To mitiagte the detrminental effects to the RV, the IRIS™ valve is implantable at 12 mm with a 12-Fr delivery catheter. As the valve annulus grows, the valve would be balloon expanded up to 20 mm. Methods: The IRIS™ valve has been designed according to origami concepts such that its three leaflets would retain a fully-coapted form as it is expanded to a larger size. Here we report our methods and results of implantation in 9-17Kg Yucatan pigs. Results: The IRIS™ valve is made of thin porcine pericardial leaflets sewn into a laser-cut stainless-steel stent. The stented valve is covered with an ePTFE skirt to mitigate paravalvular leak. The IRIS™ valve is fully crimped over a 12-Fr delivery catheter for transfemoral implantation. We have successfully implanted the valve at the native pulmonary valve position with minimal regurgitation in three pigs ranging from 9 to 17kg with varying pulmonary annulus sizes. Conclusions: The IRIS™ transcatheter pulmonary valve has been successfully developed according to proprietary origami concepts. Using the 12Fr delivery catheter, the smallest delivery profile reported, we successfully implanted the IRIS™ valve within the pulmonary annulus of mini pigs with encouraging results.

The Public Finance Position of Immigrants in Europe: A Quantile Regression Approach

We contrast the net fiscal position (NFP) of immigrants versus natives using data from the European Survey on Living Conditions for 2007–2015. Using a quantile regression approach, we find that European and non-European migrants have a different fiscal position from natives only on the extreme tails of the NFP distribution. Non-EU migrants contribute even more than natives in the top quantile of the NFP, but they are more fiscally dependent than native citizens in the lowest quantile. These findings suggest that immigrants are not a public finance burden and do not increase public spending in the destination country. We also examine the relationship between migrants’ fiscal position and the fiscal perception of natives versus migrants as measured in the European Social Survey. We believe that by examining the effects of migrants on public spending, we can gain valuable insights into the economic implications of immigration and develop evidence-based migration policies, fostering integration.

The Mastoid Crevasse and 3-Dimensional Considerations in Deep Plane Neck Lifting.

Advances in face and neck lifting involve release of tethering points along the superficial musculoaponeurotic system-platysma complex to freely manipulate the deep natural glide plane in the face and neck. The aim of this article was to determine a combination of deep plane techniques for addressing the face and neck and to elucidate, for the first time, a measurable endpoint for the gonial angle. Analysis of deep plane tethering and decussation zones was also undertaken. Extended deep plane surgery performed in 79 patients (158 hemifaces; age, 30-75 years; 95% female), over a 3-month period, was reviewed. Patients were followed for 1 year. Measurements were performed systematically during deep plane face and neck lifting. Before intervention, the mean [standard deviation] gonial depth was 9.4 [3.6] mm on the left and 8.3 [2.7] mm on the right. The mean depth created below the gonial angle when measuring the traditional suspension to the anterior mastoid was 15.8 [3.3] mm on the left and 13.7 [2.5] mm on the right. The distance postoperatively when measuring the gonial depth after performing the crevasse technique was 23.2 [2.2] mm on the left and 22.5 [2.5] mm on the right. This represents a mean increase in the advancement of 7.4 mm on the left and 8.8 mm on the right (average, 8.1 mm) which was demonstrated to be statistically significant bilaterally (P < .0001). The deep plane techniques described here aid manipulation of the deep plane and deep neck space, while also providing measurable endpoints and more effective modes of fixation by utilizing the mastoid crevasse. The use of techniques that release tension and allow redrape produce the most natural and well-balanced results.

Arthroscopic In Situ Biceps Tenodesis Using a Double Loop-and-Tack Knotless Suture Anchor

The long head biceps tendon is a common culprit of anterior shoulder pain and dysfunction that can be surgically treated with tenotomy or tenodesis. Many techniques exist for tenodesis. This article submits an arthroscopic technique using two loop-and-tack sutures and a knotless suture anchor to tenodese the long head biceps tendon in the proximal bicipital groove in situ. The advantage of this technique is that it maintains the biceps in its native position by performing tenodesis before tenotomy. Most other techniques attempt to restore native position of the biceps through approximation. The transverse humeral ligament is also released to decompress the bicipital groove. This technique can be used to treat isolated biceps pathology or combined with rotator cuff and labral procedures.

Effect of Capitolunate Positioning on Outcomes in Scaphoid Excision and 4-Bone Fusion Patients.

Scaphoid excision and 4-bone fusion (4BF) is a surgical procedure to treat scapholunate advanced collapse. Some surgeons align the lunate over the capitates, whereas others leave the capitate in its uncovered native position. The capitolunate angle may affect long-term outcomes. This study examined whether postsurgical outcomes differed based on these differences in positioning. A retrospective analysis was performed for patients that underwent a 4BF between 2006 and 2020. Wrist range of motion; pain (0-10); and Disabilities of the Arm, Shoulder, and Hand (DASH) scores were recorded. The width of the capitate, the width of the lunate contacting the capitate, and the capitolunate angle were measured. Pearson correlations and t tests were performed. For t tests of capitolunate uncovering, patients were divided into 2 groups: patients with 0% capitate uncovering and patients with >0% uncovering. For capitolunate angle, the 2 groups were patients with a capitolunate angle of ≤10° and patients with a capitolunate angle of >10°. There was a significant correlation between capitate coverage and wrist extension, but no correlation for flexion, pain, or DASH scores. Group 1 (0% uncovering) had increased wrist extension and decreased pain compared with group 2 (>0% uncovering). There were no significant correlations or differences in the analyses of capitolunate angle's impact on outcomes. In patients undergoing 4BF, those who had the lunate aligned to completely cover the capitate head had improved wrist extension and pain compared with patients where the capitate head was left partially uncovered. Capitolunate angle was not predictive of postsurgical outcomes.

Radiographic comparison of eccentric stemmed vs. concentric stemless prosthetic humeral head positioning after anatomic total shoulder arthroplasty

Maintaining premorbid proximal humeral positioning is an essential consideration of anatomic total shoulder arthroplasty (aTSA), as malposition of the prosthetic humeral head can result in poor clinical outcomes. Stemless aTSA prosthetic heads are usually concentric, while stemmed aTSA prosthetic heads are typically eccentric in nature. Therefore, the purpose of this study was to compare the ability to restore native humeral head position between stemmed (eccentric) vs. stemless (concentric) aTSA. Postoperative anteroposterior radiographs of 52 stemmed and 46 stemless aTSAs were analyzed. A best-fit circle was created using previously published and validated techniques to represent the premorbid humeral head position and axis of rotation. This circle was juxtaposed with another circle following the arc of the implant head. Next, the offset in center of rotation (COR), radius of curvature (RoC), and humeral head height above the greater tuberosity (HHH) were measured. Additionally, based on prior studies, an offset of >3 mm at any point between the implant head surface and premorbid best-fit circle was considered significant and further classified as overstuffed or understuffed. RoC deviation was significantly greater in the stemmed cohort than the stemless cohort (1.19±1.37 mm vs. 0.65±1.17 mm, P=.025). There was no statistically significant difference in deviation from premorbid humeral head between the stemmed and stemless cohorts for COR (3.20±2.28 mm vs. 3.23±2.09 mm, P=.800) or HHH (1.12±3.27 mm vs. 0.92±2.70 mm, P=.677). When comparing overstuffed implants to appropriately placed implants, there was a significant difference in overall COR deviation in stemmed implants (3.93±2.51 mm vs. 1.92±1.05 mm, P<.001). Superoinferior COR deviation (stemmed: 2.38±3.01 mm vs. -0.61±1.59 mm, P<.001; stemless: 2.70±1.75 mm vs. -0.16±1.87 mm, P<.001), mediolateral COR deviation (stemmed: 0.79±2.65 mm vs. -0.62±1.27 mm, P=.020; stemless: 0.40±1.41 mm vs. -1.13±1.96 mm, P=.020), and HHH (stemmed: 3.61±2.73 mm vs. 0.50±1.31 mm, P<.001; stemless: 3.98±1.18 mm vs. 0.53±1.41 mm, P<.001) were significantly different between overstuffed implants and appropriate implants in both the stemmed and stemless cohorts. Stemless and stemmed aTSA implants have similar rates of reproducing satisfactory postoperative humeral head COR with both producing COR deviation most commonly in the superomedial direction. Deviation in HHH contributes to overstuffing in both stemmed and stemless implants, COR deviation contributes to overstuffing in stemmed implants, while RoC (humeral head size) is not associated with overstuffing. Based on this study, it appears that neither eccentric nor concentric prosthetic heads are superior in recreating premorbid humeral head position.

Three-Dimensional Measurement of Proximal Humerus Fractures Displacement: A Computerized Analysis.

Neer's classification for proximal humerus fractures (PHFs) uses 10 mm and 45° thresholds to distinguish displaced fragments. While this system was originally developed referencing 2D X-rays, fracture displacements occur in three dimensions. Our work aimed to develop a standardized and reliable computerized method for measuring PHF 3D spatial displacements. CT scans of 77 PHFs were analyzed. A statistical shape model (SSM) was used to generate the pre-fracture humerus. This predicted proximal humerus was then used as a "layer" to manually reduce fragments to their native positions and quantify translation and rotation in three dimensions. 3D computerized measurements could be calculated for 96% of fractures and revealed that 47% of PHFs were displaced according to Neer's criteria. Valgus and varus head rotations in the coronal plane were present in 39% and 45% of cases; these were greater than 45° in 8% of cases and were always associated with axial and sagittal rotations. When compared to 3D measurements, 2D methods underestimated the displacement of tuberosity fragments and did not accurately assess rotational displacements. The use of 3D measurements of fracture displacement is feasible with a computerized method and may help further refine PHF analysis and surgical planning.

3D assessment of graft malposition after ACL reconstruction: Comparison of native and 11o'clock ligament orientations

BackgroundFemoral tunnel malposition makes up the majority of technical failures for ACL reconstructive surgery. The goal of this study was to develop adolescent knee models that accurately predict anterior tibial translation when undergoing a Lachman and pivot shift test with the ACL in the 11o’clock femoral malposition (Level of Evidence: IV). MethodsFEBio was used to build 22 subject-specific tibiofemoral joint finite element representations. To simulate the two clinical tests, the models were subject to loading and boundary conditions established in the literature. Clinical, historical control data were used to validate the predicted anterior tibial translations. ResultsA 95% confidence interval showed that with the ACL in the 11o’clock malposition, the simulated Lachman and pivot shift tests produced anterior tibial translations that were not statistically different from the in vivo data. The 11o’clock finite element knee models resulted in greater anterior displacement than those with the native (approximately 10o’clock) ACL position. The difference in anterior tibial translation between the native and 11o’clock ACL orientations was statistically significant. ConclusionClinically, by understanding the impact that ACL orientation has in anterior tibial displacement biomechanics, surgical interventions can be improved to prevent technical errors from occurring. The integration of this methodology into surgical practice not only allows for anatomical visualization prior to surgery, but also creates the opportunity to optimize graft placement, thus improving post-surgical outcomes.