Geometry and Unitarity of Scalar Fields Coupled to Gravity.

We formulate scalar field theories coupled nonconformally to gravity in a manifestly frame-independent fashion. Physical quantities such as the S matrix should be invariant under field redefinitions, and hence can be represented by the geometry of the target space. This elegant geometric formulation, however, is obscured when considering the coupling to gravity because of the redundancy associated with the Weyl transformation. The well-known example is the Higgs inflation, where the target space of the Higgs fields is flat in the Jordan frame but is curved in the Einstein frame. Furthermore, one can even show that any geometry of O(N) nonlinear σ models can be flattened by an appropriate Weyl transformation. In this Letter, we extend the notion of the target space by including the conformal mode of the metric, and show that the extended geometry provides a compact formulation that is manifestly Weyl-transformation or field-redefinition invariant. We identify the cutoff scale with the inverse of square root of the extended target-space curvature and confirm that it coincides with that obtained from two-to-two scattering amplitudes based on our formalism.

New Constraint on Primordial Lepton Flavor Asymmetries.

A chiral chemical potential present in the early Universe can source helical hypermagnetic fields through the chiral plasma instability. If these hypermagnetic fields survive until the electroweak phase transition, they source a contribution to the baryon asymmetry of the Universe. In this Letter, we demonstrate that lepton flavor asymmetries above |µ|/T∼9×10^{-3} trigger this mechanism even for vanishing total lepton number. This excludes the possibility of such large lepton flavor asymmetries present at temperatures above 10^{6} GeV, setting a constraint which is about 2 orders of magnitude stronger than the current CMB and BBN limits.

Clinical Outcomes After Anterior Cruciate Ligament Reconstruction in Patients With a Concomitant Segond Fracture: A Systematic Review.

BACKGROUND: The Segond fracture can be observed in patients with an anterior cruciate ligament (ACL) tear. It is unclear whether the Segond fracture affects clinical outcomes after ACL reconstruction. PURPOSE: To investigate whether the presence of a concomitant Segond fracture affects clinical outcomes after ACL reconstruction and to compare clinical outcomes when a Segond fracture is repaired surgically or left unrepaired. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: Three databases (PubMed, Embase, Cochrane Library) were searched in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines on July 27, 2020. Relevant studies regarding ACL injury with concomitant Segond fracture treated by primary ACL reconstruction were screened in duplicate. Data regarding patient characteristics and clinical outcomes were extracted. Descriptive data are presented, and a random-effects model was used to pool amenable data. RESULTS: A total of 5 studies examining 2418 patients (987 female; 40.8%), mean age 25.4 years, were included in this study. There were 304 patients with a Segond fracture (mean age, 28.1 years; 35.9% female) and 2114 patients without a Segond fracture (mean age, 25.1 years; 41.5% female). Four studies directly compared outcomes between patients with an unrepaired Segond fracture and no Segond fracture. One study reported 12 patients who underwent ACL reconstruction and repair of a Segond fracture. Among 4 studies, 11 of 292 (3.8%) graft failures/revision surgeries were reported in the groups that had Segond fracture, whereas 145 of 2114 (6.9%) graft failures/revision surgeries were reported in groups that did not have Segond fracture. No significant difference was observed in the risk of graft failure between the 2 groups, with a pooled risk ratio of 0.59 (95% CI, 0.32-1.07; P = .08; I2 = 0%). No clinically significant differences were observed with regard to International Knee Document Committee score, Lysholm score, Tegner activity scale, and postoperative knee laxity between the group with Segond fracture and those without. CONCLUSION: An unrepaired Segond fracture does not appear to have any significant negative effect on postoperative stability or risk of graft failure or revision surgery after ACL reconstruction. Future prospective studies may be warranted to confirm the finding that patients with combined ACL injury and Segond fracture may have outcomes comparable with those of ACL-injured patients without a Segond fracture when isolated ACL reconstruction is performed.

Risk factors of residual pivot-shift after anatomic double-bundle anterior cruciate ligament reconstruction.

INTRODUCTION: Although anterior cruciate ligament reconstruction (ACLR) is considered a successful procedure, residual pivot-shift after surgery remains to be solved. The purpose of this study was to comprehensively evaluate the risk factors of residual pivot-shift after anatomic double-bundle (DB) ACLR. MATERIALS AND METHODS: A total of 164 patients who underwent primary anatomic DB-ACLR between January 2014 and December 2019 and screw removal after the index ACLR in our hospital were included in this retrospective case-control study. The manual pivot-shift test was performed under general anesthesia during screw removal surgery, and patients with grade 1 or higher pivot-shift were classified as the positive pivot-shift group, and those with grade 0 were defined as the negative pivot-shift group. Univariate and logistic regression analyses were performed to identify the factors associated with postoperative residual pivot-shift. Assessment included sex, age, time to surgery, preoperative Tegner activity scale, preoperative pivot-shift grade, preoperative anterior tibial translation by the KT-2000 arthrometer measurement, meniscus injury and its surgical procedure, knee hyperextension, cartilage damage, Segond fracture, medial and lateral posterior tibial slope, lateral-medial slope asymmetry, participation in pivoting sport/activity at the time of injury, and return to sports at postoperative one year line. RESULTS: Postoperative positive pivot-shift was observed in 14 (8.5%) of 164 patients. The KT-2000 measurement at 1-year postoperatively was significantly higher in the residual pivot-shift-positive group than in the negative group (P < 0.05). Logistic regression analysis revealed that age of patients < 20 years [P < 0.05, odds ratio (OR): 6.1)], preoperative pivot-shift grade (P < 0.05, OR: 4.4), and hyperextended knee (P < 0.05, OR: 11.8) were risk factors of postoperative pivot-shift. There were no statistically significant differences between other variables. CONCLUSIONS: Patients < 20 years of age, with high-grade preoperative pivot-shift, or hyperextended knees had a higher risk of residual postoperative pivot-shift.

Development and Analysis of Mouse Medial Meniscus Posterior Root Tear Model.

Medial meniscus posterior root tears (MMPRT) are often associated with osteoarthritis (OA) progression and subchondral bone insufficiency fractures. This study aimed to develop the first MMPRT mouse model. The MMPRT model was created by sectioning the medial meniscus posterior root of 12-week-old CL57BL/6J male mice under stereomicroscopic observation. The sham operation and the destabilization of the medial meniscus (DMM) model groups were also created. OA progression and subchondral bone changes were evaluated histologically using the Osteoarthritis Research Society International (OARSI) subchondral bone scoring system at 2, 4, 8, and 12 weeks after surgery. Microcomputed tomography (µCT) was performed to evaluate the presence of insufficient fractures. OA progression and medial meniscus extrusion were observed in the MMPRT and DMM models 12 weeks after surgery. OA progressed in both models during the time course, without a significant difference in the OARSI score between the two groups. The subchondral bone score was significantly higher at 12 weeks than at 2 and 4 weeks in the MMPRT group, while no significant difference was found between the two groups. In the µCT analysis, destruction of the medial tibial plateau was observed in 4/40 knees, while none were observed in the DMM group. Of the four knees, destruction of the medial femoral condyle was also observed in three knees. Characteristic pathological changes were observed in the mouse MMPRT model. The mouse MMPRT model may be useful for investigating pathological changes after MMPRT.

Direct suturing quadriceps tendon to a continuous loop with a suspensory button provides biomechanically superior fixation in ACL reconstruction.

PURPOSE: To compare the biomechanical strength of different fixation configurations using suspensory buttons in a soft-tissue quadriceps tendon (QT) grafts in anterior cruciate ligament (ACL) reconstruction. METHODS: Forty bovine QTs, 6-cm long and 10-mm wide, were allocated into four groups with different suture configurations using suspensory buttons (n = 10 in each group): Group A, a baseball suture with a knot tied to the continuous loop with a suspensory button; Group B, same configuration as in Group A but with the knot tied at the opposite end of the baseball suture; Group C, a continuous loop with a suspensory button stitched directly to the QT with simple sutures, and Group D, a baseball suture tied directly to a suspensory button. Biomechanical testing was performed by preloading followed by cyclic loading for 500 cycles between 10 and 100 N. The length of elongation (mm) and maximum load to failure (N) were recorded, and compared among the four groups. RESULTS: Group C showed significantly smaller elongation (4.1 mm [95% CI 3.1-5.2]) than Group A (8.2 mm [95% CI 7.0-9.4]), Group B (10.5 mm [95% CI 7.7-13.3]), and Group D (8.5 mm [95% CI 7.0-9.9]) (A-C; P = 0.004, B-C; P = 0.0001, C-D; P = 0.0018). The maximum load to failure in Group C (386 N [95%CI 306-466]) was significantly higher than that in Group A (196 N [95% CI 141-251]), Group B (226 N [95% CI 164-289]), and Group D (212 N [95%CI 171-253]) (A-C; P = 0.0001, B-C; P = 0.0009, C-D; P = 0.0002). No significant differences were observed between Group A, B, and D in terms of elongation and maximum load to failure. CONCLUSION: The soft-tissue QT graft fixation configuration stitched directly to a continuous loop with suspensory button using simple sutures exhibits small elongation and high maximum load to failure among the four configurations. Regarding clinical relevance, direct suturing of the soft-tissue QT to a continuous loop with a suspensory button may be advantageous for femoral fixation in ACL reconstruction from a biomechanical perspective, and warrant future development of a novel fixation device using this principle.

Attenuation of Knee Osteoarthritis Progression in Mice through Polarization of M2 Macrophages by Intra-Articular Transplantation of Non-Cultured Human Adipose-Derived Regenerative Cells.

Adipose-derived regenerative cells (ADRCs) are non-cultured heterogeneous or mixed populations of cells obtained from adipose tissue by collagenase digestion. The injection of ADRCs have been tried clinically for the treatment of osteoarthritis (OA). The purpose of this study was to evaluate the effect of intra-articular transplantation of human ADRCs on OA progression in mice and the effect of ADRCs on macrophage polarization. In in vivo experiments, BALB/c-nu mice with knee OA received intra-articular transplantation of either phosphate buffered-saline or human ADRCs. OA progression was evaluated histologically and significantly attenuated in the ADRC group at both four and eight weeks postoperatively. The expression of OA-related proteins in the cartilage and macrophage-associated markers in the synovium were examined by immunohistochemistry. The numbers of MMP-13-, ADAMTS-5-, IL-1ß-, IL-6- and iNOS-positive cells significantly decreased, and type II collagen- and CD206-positive cells were more frequently detected in the ADRC group compared with that in the control group. In vitro co-culture experiments showed that ADRCs induced macrophage polarization toward M2. The results of this study suggest that the intra-articular transplantation of human ADRCs could attenuate OA progression possibly by reducing catabolic factors in chondrocytes and modulating macrophage polarization.

Wash-In Leptogenesis.

We present a leptogenesis mechanism based on the standard type-I seesaw model that successfully operates at right-handed-neutrino masses as low as a few hundred TeV. This mechanism, which we dub wash-in leptogenesis, does not require any CP violation in the neutrino sector and can be implemented even in the regime of strong wash-out. The key idea behind wash-in leptogenesis is to generalize standard freeze-out leptogenesis to a nonminimal cosmological background in which the chemical potentials of all particles not in chemical equilibrium at the temperature of leptogenesis are allowed to take arbitrary values. This sets the stage for building a plethora of new baryogenesis models where chemical potentials generated at high temperatures are reprocessed to generate a nonvanishing B-L asymmetry at low temperatures. As concrete examples, we discuss wash-in leptogenesis after axion inflation and in the context of grand unification.

Mobile Bearing Total Knee Arthroplasty for Valgus Knee Osteoarthritis with Permanent Patellar Dislocation: A Case Report and Review of the Literature.

Permanent patellar dislocation with tibiofemoral joint osteoarthritis is a relatively rare condition. To treat this condition, total knee arthroplasty with proximal or distal realignment of the extensor mechanism has been reported. We report a challenging case of an 80-year-old woman diagnosed with permanent patellar dislocation with tibiofemoral joint osteoarthritis treated by a mobile bearing total knee arthroplasty utilizing navigation system. Lateral retinaculum release was performed to improve patellar tracking; other proximal or distal realignment of the extensor mechanism was not necessary. Postoperative radiographs show stable patellar tracking and recurrent patellar dislocation was not observed. This clinical case indicates that the implant's precise alignment and rotation during total knee arthroplasty could settle anatomical abnormalities of permanent patellar dislocation and the mobile bearing insert could contribute to stabilizing patellar tracking.