Relationship between radiographic measurements and knee adduction moment using 3D gait analysis

BackgroundRadiographic factors estimate the state of the static knee joint, and it is questionable how well these parameters reflect the dynamic knee condition. The external knee adduction moment (KAM) during gait is known to be a kinetic variable contributing to osteoarthritis progression. This study aims to investigate the effects of static radiographic parameters on the dynamic KAM during gait.MethodsOverall, 123 patients (mean age, 65.7 years; standard deviation, 8.1 years; 34 men and 89 women) were included. Seven radiographic parameters including the mechanical tibiofemoral angle (mTFA), Kellgren-Lawrence grade, and ankle joint line orientation (AJLO) were measured on radiographs, and the maximum KAM and KAM-time integral in the stance phase were obtained using three-dimensional gait analysis. The correlation and multiple regression analyses were performed for identifying significant radiographic measurements associated with the KAM.ResultsMost of the radiographic measurements correlated with the maximum KAM and KAM-time integral. As a result of multiple regression analysis, the mTFA (p < 0.001) and AJLO (p = 0.003) were identified as significant factors associated with the KAM-time integral (R² = 0.450); the mTFA (p < 0.001) and AJLO (p = 0.003) were identified as a significant factor associated with the maximum KAM (R² = 0.352) in multiple regression analysis. The discriminant validity of KAM was highest at varus 5.7 degree of the mTFA and 7.5 degree of the AJLO.SignificanceThe mTFA and AJLO were significantly associated with the KAM. However, to be used as a surgical indication for corrective osteotomy, a longitudinal study is needed to validate whether the mTFA and AJLO values directly cause osteoarthritis progression as we have suggested.Level of evidenceIII.     

Long-term coordinated microstructural disruptions of the developing neocortex and subcortical white matter after early postnatal systemic inflammation

Severe postnatal systemic infection is highly associated with persistent disturbances in brain development and neurobehavioral outcomes in survivors of preterm birth. However, the contribution of less severe but prolonged postnatal infection and inflammation to such disturbances is unclear. Further, the ability of modern imaging techniques to detect the underlying changes in cellular microstructure of the brain in these infants remains to be validated. We used high-field ex-vivo MRI, neurohistopathology, and behavioral tests in newborn rats to demonstrate that prolonged postnatal systemic inflammation causes subtle, persisting disturbances in brain development, with neurodevelopmental delays and mild motor impairments. Diffusion-tensor MRI and neurite orientation dispersion and density imaging (NODDI) revealed delayed maturation of neocortical and subcortical white matter microstructure. Analysis of pyramidal neurons showed that the cortical deficits involved impaired dendritic arborization and spine formation. Analysis of oligodendrocytes showed that the white matter deficits involved impaired oligodendrocyte maturation and axonal myelination. These findings indicate that prolonged postnatal inflammation, without severe infection, may critically contribute to the diffuse spectrum of brain pathology and subtle long-term disability in preterm infants, with a cellular mechanism involving oligodendrocyte and neuronal dysmaturation. NODDI may be useful for clinical detection of these microstructural deficits.     

Effect of ligand orientation on hepatocyte attachment onto the poly(N p-vinylbenzyl-o-β-D-galactopyranosyl-D-gluconamide) as a model ligand of asialoglycoprotein

The orientation effect of galactose ligand on hepatocyte attachment was investigated. Poly(N-p-vinylbenzyl-o-β-D-galactopyranosyl-D-gluconamide)(PVLA, a β-galactose-carrying styrene homopolymer, was used as a model ligand for the asialoglycoprotein receptors on hepatocytes. PVLA was transferred onto the poly(γ-benzyl L-glutamate) (PBLG) or PBLG/poly(ethylene glycol) (PEG)PBLG Langmuir-Blodgett (LB) films as the monolayer level. The dichroic fluorescence values of the confocal microscope indicated that the PVLA transferred onto the LB films was located with a preferential orientation of its molecular axes with regard to the direction of the α-helix of polypeptide. Hepatocyte recognized well-oriented galactose moieties of the surface of PVLA through asialoglycoprotein receptors.     

Cement use in total knee arthroplasty: 40 versus 80 grams

BackgroundStudies of cement use in total knee arthroplasty (TKA) have historically addressed mechanical properties and application strategies. Recently, cement technique has been studied as a means to reduce cost. We transitioned from opening two bags (80 grams) of cement to one bag (40 grams) of cement for primary TKA to improve cost efficacy. This study investigates the radiographic outcome and cost of TKAs performed with 40 versus 80 grams of cement.MethodsTKAs from January 2017 to January 2019 were evaluated. Cement mantle and implant alignment were assessed per the Modern Knee Society Radiographic Evaluation System at four months by three blinded reviewers. Data was analyzed according to quantity of cement used. Cement mantle quality at 16 implant zones was compared. Cost was evaluated.Results163 patients (age 66.8 yrs. +/− 8.9, 51.5% female) underwent TKA with 80 grams of cement, while 142 patients (age 67.1 yrs. +/− 9.3, 56.3% female) underwent TKA utilizing 40 grams of cement. There was no significant difference in cement mantle quality. The most common zone of cement deficiency was the femoral posterior flange (9% in 40 gram group versus 4% in 80 gram group, p value = 0.08). There was no difference in implant size. Cost saving was calculated at $7,810 for the 40 gram group.ConclusionThere was no difference in radiographic cement mantle appearance between primary knees performed with 40 or 80 grams of cement. Cement usage represents a target for cost saving and opportunity to increase the value of primary TKA. Based on the current incidence of TKA in the United States, cost savings could exceed 33 million dollars annually.     

Impact of joint line orientation on clinical outcomes in bilateral Oxford mobile-bearing unicompartmental knee arthroplasty

BackgroundJoint line orientation angle (JLOA) is the angle between the knee joint line and the floor. It has been reported to be related to postoperative outcome after TKA. Regarding unicompartmental knee arthroplasty (UKA), although it can be horizontal after UKA because it is a resurfacing surgery, there are few reports about the JLOA after UKA and its impact on clinical outcomes.PurposeThe purpose of this study was to reveal the relationship between JLOA and clinical outcome after UKA.MethodsThis study included 106 knees in 53 consecutive patients with osteoarthritis who underwent simultaneous bilateral mobile-bearing UKA. Their pre- and postoperative JLOAs were measured by full-leg-length standing coronal radiographs. We also evaluated the tibial component height (TCH) as the factor which we assumed could influence JLOA. We analyzed the patients’ JLOAs, TCHs and clinical outcomes.ResultsPre- and postoperative JLOA were 0.4 ± 2.4° and 2.7 ± 2.6°, respectively. The JLOA significantly tilted medially (P < 0.0001). The JLOA significantly negatively correlated with the improvement of the clinical outcomes (Oxford Knee Score (OKS): r = 0.40, P < 0.0001, Knee Society Knee Score (KSKS): r = 0.25, P < 0.01, Knee Society Function Score (KSFS): r = 0.22, P = 0.02). The TCH showed a positive correlation with postoperative JLOA and with the postoperative JLOA change (r = 0.45, P < 0.001; r = 0.25, P < 0.01, respectively).ConclusionThe JLOA significantly tilted medially after UKA. An excessive medial tilt of the JLOA was associated with poorer postoperative outcomes of UKA. It is therefore recommended to keep the JLOA horizontal and to avoid a lower tibial cut.     

Influence of Smectic Liquid Crystallinity on Lamellar Microdomain Structure in a Main‐Chain Liquid Crystal Block Copolymer Fiber

The microlamellar and smectic liquid crystal (LC) structures of a block copolymer of a main‐chain LC polyester connected at both ends with poly(ethyl methacrylate) are investigated by fiber X‐ray scattering. In the as‐spun fiber, the lamellae are parallel to the fiber axis, while the smectic layers are perpendicular to it. Annealing the as‐spun fiber at a temperature higher than the isotropization temperature (T_i) of the LC segment preserves the lamellae, but the LC structure disappears. Further annealing the fiber at T < T_i improves the lamellar stacking coherence and aligns the smectic layers parallel to the lamellae. In contrast, annealing the as‐spun fiber at T < T_i conserves the smectic layers and arranges the lamellae in parallel to the smectic layers. Thus, the liquid crystallinity affects the lamellar ordering and orientation.

     

Influences of the depth-dependent material inhomogeneity of articular cartilage on the fluid pressurization in the human knee

The material properties of articular cartilage are depth-dependent, i.e. they differ in the superficial, middle and deep zones. The role of this depth-dependent material inhomogeneity in the poromechanical response of the knee joint has not been investigated with patient-specific joint modeling. In the present study, the depth-dependent and site-specific material properties were incorporated in an anatomically accurate knee model that consisted of the distal femur, femoral cartilage, menisci, tibial cartilage and proximal tibia. The collagen fibers, proteoglycan matrix and fluid in articular cartilage and menisci were considered as distinct constituents. The fluid pressurization in the knee was determined with finite element analysis. The results demonstrated the influences of the depth-dependent inhomogeneity on the fluid pressurization, compressive stress, first principal stress and strain along the tissue depth. The depth-dependent inhomogeneity enhanced the fluid support to loading in the superficial zone by raising the fluid pressure and lowering the compressive effective stress at the same time. The depth-dependence also reduced the tensile stress and strain at the cartilage–bone interface. The present 3D modeling revealed a complex fluid pressurization and 3D stresses that depended on the mechanical contact and relaxation time, which could not be predicted by existing 2D models from the literature. The greatest fluid pressure was observed in the medial condyle, regardless of the depth-dependent inhomogeneity. The results indicated the roles of the tissue inhomogeneity in reducing deep tissue fractures, protecting the superficial tissue from excessive compressive stress and improving the lubrication in the joint.     

Sexual Orientation Demographic Data in a Clinical Cohort of Transgender Patients

Background  There are specific issues regarding sexual orientation (SO) collection and analysis among transgender and nonbinary patients. A limitation to meaningful SO and gender identity (GI) data collection is their consideration as a fixed trait or demographic data point. Methods  A de-identified patient database from a single electronic health record (EHR) that allows for searching any discrete data point in the EHR was used to query demographic data (sex assigned at birth and current GI) for transgender individuals from January 2011 to March 2020 at a large urban tertiary care academic health center. Results  A cohort of transgender individuals were identified by using EHR data from a two-step demographic question. Almost half of male identified (46.70%, n  = 85) and female identified (47.51%, n  = 86) individuals had “heterosexual/straight” input for SO. Overall, male and female identified (i.e., binary) GI aggregate categories had similar SO responses. Assigned male at birth (AMAB) nonbinary individuals ( n  = 6) had “homosexual/gay” SO data input. Assigned female at birth (AFAB) nonbinary individuals ( n  = 56) had almost half “something else” SO data input (41.67%, n  = 15). Individuals with “choose not to disclose” for GI ( n  = 249) almost all had “choose not to disclose” SO data (96.27%, n  = 232). Conclusion  Current SO categories do not fully capture transgender individuals'' identities and experiences, and limit the clinical and epidemiological utility of collecting this data in the current form. Anatomical assumptions based on SO should be seen as a potential shortcoming in over-reliance on SO as an indicator of screening needs and risk factors.     

三种机用镍钛锉预备弯曲根管的中心定位能力比较研究

目的　评价M3-Pro 2018、M3-L铂金版及ProTaper universal三种机用镍钛锉预备弯曲根管的中心定位能力。方法　收集2018年10月至2019年3月在常州市第一人民医院口腔科拔除的上颌第一磨牙,筛选出30个近中颊根管弯曲度为20 ~ 40°的近中颊根,随机分成3组,分别为M3-Pro组、M3-L组和ProTaper组,每组10个样本,分别使用M3-Pro 2018机用镍钛锉、M3-L铂金版单支锉系统及ProTaper universal机用镍钛锉预备根管。各样本在处理前后均使用CBCT扫描并利用软件mimics17.0测算距根尖5 mm范围内每毫米处的根管偏移量及轴中心率。结果　距根尖1 mm区域,M3-Pro组、M3-L组和ProTaper组的根管偏移量均值分别为0.06、0.16和0.22 mm,轴中心率均值分别为0.86、0.71和0.49,3组间差异均有统计学意义（F值分别为3.404和3.499,均P < 0.05）。距根尖3 mm区域,M3-Pro组、M3-L组和ProTaper组的根管偏移量均值分别为0.13、0.19和0.26 mm,轴中心率均值分别为0.63、0.51和0.32,3组间差异均有统计学意义（F值分别为7.567和3.996,均P < 0.05）。进一步两两比较发现,距根尖1 mm和3 mm处M3-Pro组与ProTaper组的根管偏移量及轴中心率的差异有统计学意义（P < 0.05）;距根尖3 mm处M3-L组与ProTaper组的根管偏移量差异有统计学意义（P < 0.05）,而两组的轴中心率差异无统计学意义（P > 0.05）。其余观测面上的根管偏移量和轴中心率在3组之间的差异均无统计学意义（均P > 0.05）。结论 M3-Pro 2018机用镍钛锉在弯曲根管的根尖区预备中能更好地顺应根管形状,减小根管偏移量,中心定位能力优于其他两种镍钛锉。