Insert Thickness Research Articles

Comparison of Intraoperative Soft Tissue Balance Between Cruciate-Retaining and Posterior-Stabilized Total Knee Arthroplasty Performed by a Newly Developed Medial Preserving Gap Technique

BackgroundMedial stability of the knee is considered to be associated with good clinical results after total knee arthroplasty (TKA). This study aimed to compare intraoperative soft tissue balance between cruciate-retaining (CR) and posterior-stabilized (PS) TKA performed by a newly developed medial preserving gap technique, which aimed at preserving medial stability throughout the range of motion. MethodsSeventy CR-TKAs and 70 PS-TKAs were performed in patients with varus type osteoarthritis with the novel technique guided by tensor measurements. Final intraoperative soft tissue balance with femoral trial component in place and patellofemoral joint reduced, including the joint component gap and varus/valgus ligament balance (varus angle), with the knee at 0° (full extension), 10° (extension), 30°, 45°, 60°, 90° (flexion), 120°, and 135° (deep flexion), was measured with Offset Repo-Tensor under 40 lbs of joint distraction force. The medial compartment gap (MCG), lateral compartment gap, and medial joint looseness (MCG-polyethylene insert thickness) at each flexion angle were calculated from the measured joint component gap and varus ligament balance, and compared between CR-TKA and PS-TKA. ResultsThe MCGs from extension to deep flexion of the knee showed no significant differences between CR-TKA and PS-TKA. The lateral compartment gaps in PS-TKA from 30° to 60° of knee flexion was significantly larger than those in CR-TKA (P < .05). Medial joint looseness showed no significant differences between CR-TKA and PS-TKA which is consistent within 1 mm from extension to flexion of the knee. ConclusionPS-TKA similarly achieved medial stability comparable to CR-TKA using the medial preserving gap technique.

An analytical cutting force model for plunge milling of Ti6Al4V considering cutter runout

As one of the most efficient machining methods, plunge milling has gained more attention as a promising cutting process. This strategy is often used for roughing and semi-roughing processes for the more vibration free than other cutting operations. The motivation of this paper is that the cutting forces in plunge milling differ from that in side milling for the complex cutting condition and tool geometry. In this work, a systematic and analytical cutting force prediction model considering cutter runout for plunge milling is proposed. The detailed analysis of cutting geometry is important for modeling. The precise uncut width is calculated with consideration of the cutting step. In addition, the real-time uncut chip thickness of different inserts is calculated with consideration of the effect of cutter runout. The deduced cutting force model based on the predictive model can be used in various cutting conditions in the plunge milling process. Plunge milling tests with various cutting steps are carried out to verify the proposed model with the quantitative analysis of the results. The results indicate that the simulated results show quite good agreements with the measured cutting forces, which proves the correctness and accuracy of the proposed model.

Effect of Metallic Inserts on the Strength of Pin Joints Prepared from Glass Fiber Reinforced Composites

The present study deals with the failure analysis of pin joints by varying different geometric parameters i.e., edge distance to hole diameter (E/D) ratio and width to hole diameter (W/D) ratio. Pin joints were prepared from the glass fiber reinforced laminates incorporating the metal inserts. A range of 2 to 5 and 3 to 6 was considered for E/D and W/D ratios, respectively. The stress around the hole was redistributed by incorporating the metal inserts in the hole to increase the load carrying capacity. To predict the failure loads and failure modes numerically, progressive damage analysis along with Hashin failure criteria was used in the pin joints. Strength of the pin joints increased in the range of 65 per cent to 92 per cent with metal insert due to the redistribution of the stresses around the hole. Progressive damage analysis gave a good correlation with experimental findings. Thereafter, the strength of the joint was predicted by varying the thickness of the metal inserts.

AZO/Ag/AZO transparent flexible electrodes on mica substrates for high temperature application

AZO/Ag/AZO transparent flexible electrodes were fabricated on mica substrates by magnetron sputtering at room temperature. Effect of Ag inserting layer thickness on the optical and electrical properties of AZO/Ag/AZO was investigated. The Haacke figure of merit (FOM) exhibited a maximum of 30.2 × 10−3 Ω−1 with 8 nm's Ag inner layer. It had low resistivity of 3.5 × 10−5 Ω cm, average transmittance values of 83.1% in the visible wavelength region. Moreover, thermal durability of AZO/Ag(8 nm)/AZO was evaluated by annealing in vacuum for 0.5 h at different temperature. The FOM can be enhanced while the sample was annealed below 350 ℃. The resistivity and transmittance are respectively 3.69 × 10−4 Ω cm and 87.0% even after high temperature annealing up to 750 ℃. In addition, there was no appreciable change in the sheet resistance of multilayers after a severe bending test. The results indicate that the flexible and withstanding high temperature AZO/Ag/AZO multilayer transparent electrodes grown on mica have potential application for the next-generation flexible optoelectronics.

Anatomia descritiva da inserção femoral do ligamento cruzado anterior

ObjectiveTo evaluate the morphology of the anterior cruciate ligament (ACL) femoral insertion in order to describe its anatomical features and insertion site location, with the aim of verifying if the ACL femoral insertion has individual characteristics and to provide information for appropriate femoral tunnel placement on anatomic ACL reconstruction. MethodsSixteen knees obtained from amputations were studied. The ACL femoral bundles and insertion shape were observed macroscopically, and the ligaments insertion length and thickness were measured with a digital caliper. The distances between the limits of the ligament to the articular cartilage, and the measurement of the area of insertion were checked using ImageJ software. ResultsThe ACL femoral insertion site was eccentric, closer to the deep condyle cartilage. In ten knees (62.5%), the ACL femoral insertion was oval; the mean length of the insertion was 16.4mm, varying from 11.3 to 19.3mm, the mean thickness varied from 7.85 to 11.23mm, and the mean area of the insertion was 99.7 mm2, varying from 80.9 a 117.2 mm2. The mean distances between the limits of the ligament to the superficial, deep, and inferior articular cartilage were 9.77±1.21, 2.60±1.20, and 1.86±1.15mm, respectively. ConclusionThere was a 30% to 40% difference between the minimum and maximum results of measurements of ACL femoral insertion length, thickness, and area demonstrating an important individual variation. The insertion site was eccentric, closer to the deep cartilage of the lateral femoral condyle.

Tunable perpendicular anisotropic magnetoresistance in CoO/Co/Pt heterostructures

Transport properties of magnetron-sputtered CoO/Co/Pt heterostructures were investigated by physical property measurement system. Different types of magnetoresistance are observed in the heterostructures, including isotropic anisotropic magnetoresistance (AMR), AMR with geometric size effect, and interfacial effect. A reversal in sign of perpendicular AMR is found in the film CoO(3 nm)/Co(3 nm)/Pt(3 nm) compared to the film CoO(3 nm)/Co(3 nm)/CoO(3 nm), which is associated with Pt. Moreover, perpendicular AMR is tunable in the films CoO(3 nm)/Co(3 nm)/CoO(t)/Pt(3 nm) and CoO(3 nm)/Co(3 nm)/Pt(t)/CoO(3 nm) at will, with either positive or negative value, by varying the inserting layer thickness. The electronic structure information of the samples was measured by X-ray photoelectron spectroscopy (XPS). The spin-related transport and XPS results manifest that magnetic proximity effect, surface scattering, together with oxygen migration contribute to the tunable function of Pt.

Does Image Derived Instrumentation Alter Revision Rates? An AOANJRR Analysis

Objectives:Image Derived Instrumentation (IDI) has been introduced into regular use in modern day total knee arthroplasty (TKA) with many potential benefits touted. Despite this, much of the research involving IDI has failed to prove any significant benefit in alignment, operative time, blood loss and cost. The purpose of this study, the first of its kind, was to compare IDI with non-IDI TKA with respect to rate of revision.Methods:The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) was queried to analyse the survivorship of primary TKAs using IDI reported to the AOANJRR, between April 2009 to December 2014, compared with those without IDI instrumentation. Subgroup analysis was performed to determine the effect of polyethylene insert thickness upon IDI outcomes. The Kaplan-Meier method and proportional hazards models were used to determine the cumulative rates of revision and which prostheses or circumstances lead to an increased risk of revision.Results:In the period studied, there were 11197 primary TKAs performed utilising IDI. This was 4.8% of all primary TKAs during this period. The overall rate of revision/100 observed years was 1.07 in the PSI group, compared with, 0.82 in the standard group. This was equivalent to a hazard ratio (HR) of 1.15 (1.01,1.31; p=0.041). Posterior stabilised (PS) knees in particular showed an increased risk when compared with minimally stabilised knees when using IDI (HR=1.49; p=0.002) and non-IDI PS knees (HR=1.30; p=0.014). Subgroup analysis of the PSI (Zimmer); Signature (Vanguard) and Visionaire (Smith and Nephew) systems by polyethylene insert thickness found varied alteration in revision rates. Of the specific prosthetic combinations examined the NEXGEN CR FLEX/NEXGEN >11 mm poly (909 pts) HR 1.83 p=0.022 and GII Oxinium PS/GII <11 mm poly (868 pts) HR 1.45 p=0.049 were found to have significantly elevated risk of revision with the use of IDI.Conclusion:Using the AOANJRR we have shown that in primary TKAs, the use of IDI is associated with an increased overall revision rate. This is particularly prevalent in those knees using posterior stabilisation. The effect of polyethylene insert thickness varied dependent on manufacturer. The reasons for this cannot be determined from this analysis but suggest caution should be exercised in relation to this technology. Further study is warranted to better understand the reasons for increased revision rates.

The Bow Tie Shape of the Anterior Cruciate Ligament as Visualized by High-Resolution Magnetic Resonance Imaging

Background: Although numerous studies have examined the anatomic characteristics of the anterior cruciate ligament (ACL), its actual shape remains unclear. Purpose: To determine the average shape of the ACL by analyzing its cross section through the use of high-resolution magnetic resonance imaging (MRI) data. Study Design: Descriptive laboratory study. Methods: The study included 96 MRIs, conducted using a 3.0-T magnet, to analyze the shape of the ACL. Three-dimensional, curved multiplanar reconstruction was used to obtain cross sections at 7 points (femoral insertion; midsubstance 1, 2, 3, 4, and 5 from the femoral side to the tibial side; and tibial insertion). The width and thickness of cross sections were measured by 2 independent observers, and the ratio of width to thickness was calculated to determine the proportions of each cross section. The 7 cross sections were accumulated and standardized to generate an average model through the use of image analysis software developed by the authors. Results: The mean ± SD width (femoral insertion, 17.02 ± 2.17 mm; tibial insertion, 17.33 ± 2.03 mm) and thickness (femoral insertion, 11.03 ± 1.75 mm; tibial insertion, 10.09 ± 1.70 mm) of both insertions were significantly larger than those of midsubstance 4 (width, 9.99 ± 1.87 mm; thickness, 6.53 ± 1.25 mm) (P < .001). The mean ratios of width to thickness of the 7 cross sections from femoral insertion to tibial insertion were 1.57 ± 0.23, 3.36 ± 0.57, 3.07 ± 0.81, 2.18 ± 0.54, 1.56 ± 0.32, 2.16 ± 0.48, and 1.75 ± 0.28, respectively. The shape of the cross section at midsubstance 4 was an oval isthmus, which was the most narrow and well-balanced shape. It was transformed into a wide band at midsubstance 1 and 5. The shape of the femoral insertion was semicircular, with its anterior side slightly straight and its posterior side convex. The tibial insertion was kidney bean–shaped. Conclusion: On 3.0-T MRI, the ACL has a “bow tie” shape, including an oval isthmus, with a semicircular femoral insertion and kidney bean–shaped tibial insertion. Clinical Relevance: The measurement method will allow surgeons to quantitatively diagnose partial injuries of the ACL using a noninvasive system in actual patients.

Turbulent heat transfer past a sudden expansion with a porous insert using a nonlinear model

ABSTRACTThis work presents numerical investigations for turbulent flow and heat transfer in a backward-facing step with and without porous inserts. Two classes of the model were employed, namely linear and nonlinear turbulence closures. The entire set of transport equations was discretized by means of the control volume method and the system of algebraic equations obtained was relaxed using the SIMPLE (Semi Implicit Pressure-Linked Equations) method. Results were first validated against the experimental data and the simulations follow experimental values and trends. Computations further indicated that when using the porous insert, the size, shape, and length of the recirculating region were drastically reduced in addition to being pushed toward the channel exit, leading eventually to a complete bubble suppression for thicker inserts. A more permeable medium gave better results in quickly suppressing the circulatory motions. By including porous inserts in the channel, turbulence generated due to the shear inside the recirculating region was damped, whereas high levels of k were concentrated within the permeable structure. Large variations for the skin friction factor along the bottom wall were also smoothed out by placing inserts, spanning from a typical distribution for an unobstructed back-step flow to a standard parallel channel flow distribution as the inserts got ticker. On the other hand, at the upper wall, flow pushed toward the top surface gave rise to a sudden increase of the skin friction factor, which was later stabilized downstream the flow. Heat transfer analysis followed showing damping for Nu at the bottom wall as the thickness of the porous substrate was increased. Overall, the thickness of the insert played a dominant role in changing the final flow and heat transfer characteristics rather than the porosity or permeability of the porous material. Finally, this work indicated that the sudden increase of Nu around the reattachment point, known to be undesirable in many practical situations for causing additional thermomechanical loads on the surface, may by avoided by the use of a porous obstacle past the back-step.

Enhancement of voltage-controlled magnetic anisotropy through precise control of Mg insertion thickness at CoFeB|MgO interface

We studied the impact of different insertion layers (Ta, Pt, and Mg) at the CoFeB|MgO interface on voltage-controlled magnetic anisotropy (VCMA) effect and other magnetic properties. Inserting a very thin Mg layer of 0.1–0.3 nm yielded a VCMA coefficient of 100 fJ/V-m, more than 3 times higher than the average values of around 30 fJ/V-m reported in Ta|CoFeB|MgO-based structures. Ta and Pt insertion layers also showed a small improvement, yielding VCMA coefficients around 40 fJ/V-m. Electrical, magnetic, and X-ray diffraction results reveal that a Mg insertion layer of around 1.2 nm gives rise to the highest perpendicular magnetic anisotropy, saturation magnetization, as well as the best CoFe and MgO crystallinity. Other Mg insertion thicknesses give rise to either under- or over-oxidation of the CoFe|MgO interface; a strong over-oxidation of the CoFe layer leads to the maximum VCMA effect. These results show that precise control over the Mg insertion thickness and CoFe oxidation level at the CoFeB|MgO interface is crucial for the development of electric-field-controlled perpendicular magnetic tunnel junctions with low write voltage.

Agreement Between Three Optical Coherence Tomography Devices to Assess the Insertion Distance and Thickness of Horizontal Rectus Muscles.

To assess the agreement between two different spectral domain (SD-OCT) and one swept source (SS-OCT) optical coherence tomography device to measure the insertion distance and the thickness of the horizontal rectus muscles. Seventy eyes from 35 healthy patients were studied. Three OCT instruments-Spectralis (Heidelberg Engineering Inc., Heidelberg, Germany), Cirrus 5000 (Carl Zeiss Meditec, Dublin, CA), and Triton (Topcon, Inc., Tokyo, Japan)-were used to measure the limbus insertion distance and the thickness of the lateral rectus and medial rectus muscles. The intraclass correlation coefficient (ICC) was calculated to determine the reproducibility and the agreement between the three methods. Measurement of the limbus insertion distance was possible in 100% of cases with the three OCT devices. The thickness could be measured in 75% or more patients with Spectralis, 74% or more with Cirrus, and 78% or more with Triton. The agreement of the insertion distance measurements between the three devices ranged from an ICC of 0.629 or greater to 0.887; for the muscle thickness, the ICC ranged from 0.495 or greater to 0.854. The best agreement existed between the Spectralis and Topcon devices for insertion distance (ICC = 0.715 to 0.887) and for muscle thickness (ICC = 0.641 to 0.854). The reproducibility of each device was good and was higher for insertion distance (ICC = 0.880) than for muscle thickness (ICC = 0.736). The highest reproducibility values were obtained with Triton. The three OCT devices permitted accurate and reproducible measurements of the limbus insertion distance and the thickness of the horizontal rectus muscles, showing moderate to good agreement between the SS-OCT and the two SD-OCT instruments. [J Pediatr Ophthalmol Strabismus. 2017;54(3):168-176.].

PEEK and CFR-PEEK as alternative bearing materials to UHMWPE in a fixed bearing total knee replacement: An experimental wear study

New bearing materials for total joint replacement have been explored as the need to improve longevity and enhance performance is driven by the changing demands of the patient demographic. Carbon-reinforced PEEK has demonstrated good wear characteristics in experimental wear simulation in both simple geometry pin-on-plate studies and in total hip joint replacement. Carbon reinforced PEEK CFR-PEEK has the potential to reduce tibial insert thickness and preserve bone in the knee.This study investigated the wear performance of PEEK and CFR-PEEK in a low conformity total knee replacement configuration. Custom-made flat inserts were tested against cobalt-chromium femoral bearings in a knee wear simulation for a period of three million cycles. Wear was assessed gravimetrically at intervals throughout the study.The wear rates of both PEEK and CFR-PEEK were very high and almost two orders of magnitude higher than the wear rate of UHMWPE under comparable conditions. Evidence of mechanical failure of the materials, including surface cracking and delamination was observed in both materials.This study highlights that these materials may not be suitable alternatives for UHMWPE in low-conformity designs.

Effect of Mg-Al insertion on magnetotransport properties in epitaxial Fe/sputter-deposited MgAl2O4/Fe(001) magnetic tunnel junctions

We investigated the effect of an Mg-Al layer insertion at the bottom interface of epitaxial Fe/MgAl2O4/Fe(001) magnetic tunnel junctions (MTJs) on their spin-dependent transport properties. The tunnel magnetoresistance (TMR) ratio and differential conductance spectra for the parallel magnetic configuration exhibited clear dependence on the inserted Mg-Al thickness. A slight Mg-Al insertion (thickness &amp;lt; 0.1 nm) was effective for obtaining a large TMR ratio above 200% at room temperature and observing a distinct local minimum structure in conductance spectra. In contrast, thicker Mg-Al (&amp;gt; 0.2 nm) induced a reduction of TMR ratios and featureless conductance spectra, indicating a degradation of the bottom-Fe/MgAl2O4 interface. Therefore, a minimal Mg-Al insertion was found to be effective to maximize the TMR ratio for a sputtered MgAl2O4-based MTJ.

Conversion Total Knee Arthroplasty after Failed High Tibial Osteotomy.

Clinical results of high tibial osteotomy (HTO) deteriorate over time despite the initial satisfactory results. Several knees may require a conversion to total knee arthroplasty (TKA) because of failure such as the progression of degenerative osteoarthritis and the loss of the correction angle. It is important to know the long-term survival rate and common reason of failure in HTO to inform patients of postoperative expectations before surgery and to prevent surgical errors during surgery. In addition, it has been reported that clinical and radiological results, revision rate, and complication rate were poorer than those in patients without a previous HTO. There are few review articles that describe why conversion TKA after HTO is surgically difficult and the results are poor. Surgeons have to avoid the various complications and surgical errors in this specific situation. We would like to present the considering factors and technical difficulties during conversion TKA after HTO with a review of the literature. We could conclude through the review that the correction of deformity, lower amount of tibial bone resection, and sufficient polyethylene insert thickness, restoration of the joint line height, and adequate ligament balancing can be helpful in overcoming the technical challenges encountered during TKA following HTO.

Intraoperative factors affecting conversion from cruciate retaining to cruciate substituting in total knee arthroplasty.

The purpose of this study was to analyse the factors affecting the conversion from posterior cruciate ligament (PCL)-retaining (CR) to PCL-substituting (PS) prostheses during total knee arthroplasty (TKA). A total of 920 TKAs, which had been preoperatively planned to undergo implantation of CR-type prostheses, were reviewed retrospectively. Of these, 83 knees (9.0%) were converted intraoperatively to PS prostheses. The clinical and radiological factors of the non-converted (CR) and converted (PS) groups were compared. Clinically, age, gender, body mass index, angle of flexion contracture, size of the femoral component, and thickness of the polyethylene insert were compared between the CR and PS groups. Radiologically, the severity of the varus deformity and the posterior tibial slope angle (PSA) were compared between the CR and PS groups. No significant differences in age, gender, body mass index, range of motion, thickness of the polyethylene insert, or severity of varus deformity were identified. The average preoperative angle of flexion contracture was 5.9°±7.4° in the CR group and 8.1°±9.1° in the PS group (p=0.002). The average preoperative PSA was 9.6°±4.0° in the CR group and 11.0°±5.0° in the PS group (p=0.018). The conversion rates to a PS-type femoral component of size C, D, and E were 13.1, 7.0, and 6.3%, respectively (p=0.004). The conversion rate from CR- to PS-type prostheses was high in patients with severe flexion contracture, steep posterior slope, and a small femoral component size. These factors should be carefully considered for appropriate selection of prosthesis type. IV.

Designing high performance metal-mMoS2 interfaces by two-dimensional insertions with suitable thickness.

Thickness has been proved to have significant influence on the physical properties of two-dimensional (2D) materials and their corresponding devices. Understanding the effect of the thickness of 2D insertions on the contact properties of metal-monolayer MoS2 interfaces (viz. metal-mMoS2 interfaces) is vital to designing high performance mMoS2 devices. In this work, the electronic structures, Schottky barriers, contact resistance, and tunneling barriers of scandium-mMoS2 (Sc-mMoS2) interfaces with BN and graphene insertions have been comparatively studied by density functional theory. No Schottky barriers are found at Sc-mMoS2 interfaces with monolayer 2D insertions. Although the contact resistance and charge injection efficiency of Sc-mMoS2 interfaces with monolayer insertions deteriorate relatively to those of the Sc-mMoS2 interface, they are still sufficient to realize high-performance mMoS2-based devices. Note that, upon increasing the number of layers of 2D insertions, these contact properties are further deteriorated with the increasing number of layers of insertions. Moreover, additional significant Schottky barriers are introduced into Sc-mMoS2 interfaces with multilayer BN; the nature Dirac points of graphene insertions are opened, suggesting low performances of Sc-mMoS2 interfaces with multilayer BN and graphene insertions. These variations can be understood on the basis of the orbital hybridization and charge redistribution between the Sc slab and mMoS2 layer. In addition, these characteristics are expected to occur in other metal-mMoS2 interfaces with two-dimensional material insertions. Overall, monolayer rather than multilayer two-dimensional insertions can be used to improve the transport properties of mMoS2-based devices.

Ultrathin Ceramic Membranes as Scaffolds for Functional Cell Coculture Models on a Biomimetic Scale.

Epithelial tissue serves as an interface between biological compartments. Many in vitro epithelial cell models have been developed as an alternative to animal experiments to answer a range of research questions. These in vitro models are grown on permeable two-chamber systems; however, commercially available, polymer-based cell culture inserts are around 10 μm thick. Since the basement membrane found in biological systems is usually less than 1 μm thick, the 10-fold thickness of cell culture inserts is a major limitation in the establishment of realistic models. In this work, an alternative insert, accommodating an ultrathin ceramic membrane with a thickness of only 500 nm (i.e., the Silicon nitride Microporous Permeable Insert [SIMPLI]-well), was produced and used to refine an established human alveolar barrier coculture model by both replacing the conventional inserts with the SIMPLI-well and completing it with endothelial cells. The structural–functional relationship of the model was evaluated, including the translocation of gold nanoparticles across the barrier, revealing a higher translocation if compared to corresponding polyethylene terephthalate (PET) membranes. This study demonstrates the power of the SIMPLI-well system as a scaffold for epithelial tissue cell models on a truly biomimetic scale, allowing construction of more functionally accurate models of human biological barriers.

Risk factors of post-operative malalignment in fixed-bearing medial unicompartmental knee arthroplasty

The purpose of this study was to identify risk factors of post-operative malalignment in medial unicompartmental knee arthroplasty (UKA) using multivariate logistic regression. We retrospectively enrolled 92 patients who had 127 medial UKAs. According to post-operative limb mechanical axis (hip-knee-ankle [HKA] angle), 127 enrolled knees were sorted into acceptable alignment with HKA angle within the conventional ± 3 degree range from a neutral alignment (n = 73) and outlier with HKA angle outside ± 3 degree range (n = 54) groups. Multivariate logistic regression was used to analyse risk factors including age, gender, body mass index, thickness of polyethylene tibial insert, pre-operative HKA angle, distal femoral varus angle (DFVA), femoral bowing angle (FBA), tibial bone varus angle (TBVA), mechanical distal femoral and proximal tibial angles, varus and valgus stress angles, size of femoral and tibial osteophytes, and femoral and tibial component alignment angles. Pre-operative DFVA, TBVA and valgus stress angle were identified as significant risk factors. As DFVA increased by one degree, malalignment was about 45 times probable (adjusted OR 44.871, 95% CI 2.608-771.904). Shift of TBVA and valgus stress angle to a more varus direction were also significant risk factors (adjusted OR 13.001, 95% CI 1.754-96.376 and adjusted OR 2.669, 95% CI 1.054-6.760). Attention should be given to the possibility of post-operative malalignment during medial UKA in patients with a greater varus angle in pre-operative DFVA, TBVA and valgus stress angle, especially with a greater varus DFVA, which was the strongest predictor for malalignment.

Optimization of perpendicular anisotropy of Ta-inserted double CoFeB/MgO interface MTJ’s for STT-MRAM

Ta inserts in double magnetic tunnel junctions have been shown to induce perpendicular magnetic anisotropy. We fabricated the central layers of a CoFeB/MgO based double magnetic tunnel junction with a Ta insertion layer between the free layers of the magnetic tunnel junctions. The thickness of the Ta insert and CoFeB layer were varied from 0.5 to 1.1nm and 0.9 to 1.7nm respectively, to find which minimum thickness of Ta will induce perpendicular anisotropy in the MTJ. FMR studies were performed to measure the interfacial anisotropy Ku,i. We demonstrated that the most effective stack minimized the CoFeB thickness while maximizing the Ta thickness. This was balanced with the need to keep both CoFeB layers from decoupling or becoming magnetically dead.

Polyethylene Tibial Post Fracture in a Posterior Stabilized (Genesis II) Total Knee Arthroplasty

This study reports the case of a fractured polyethylene tibial post in a 49-year-old white male patient at 4 years status post a left posterior stabilized total knee arthroplasty. The patient was doing extremely well postoperatively until he felt pain in the left knee while completing personal resistance squats. He was found to have anterior/posterior instability in flexion as well as midflexion instability. The patient underwent removal of the fractured polyethylene insert and replacement with a thicker insert. The patient had immediate resolution of his preoperative pain and instability. To our knowledge, this is the first reported case of a polyethylene tibial post fracture in a Genesis II total knee system (Smith and Nephew; Memphis, TN).