Hyperuniformity in two-dimensional periodic and quasiperiodic point patterns.

We study hyperuniform properties in various two-dimensional periodic and quasiperiodic point patterns. Using the histogram of the two-point distances, we develop an efficient method to calculate the hyperuniformity order metric, which quantifies the regularity of the hyperuniform point patterns. The results are compared with those calculated with the conventional running average method. To discuss how the lattice symmetry affects the order metric, we treat the trellis and Shastry-Sutherland lattices with the same point density as examples of periodic lattices, and Stampfli hexagonal and dodecagonal quasiperiodic tilings with the same point density as examples of quasiperiodic tilings. It is found that the order metric for the Shastry-Sutherland lattice (Stampfli dodecagonal tilings) is smaller than the other in the periodic (quasiperiodic) tiling, meaning that the order metric is deeply related to the lattice symmetry. Namely, the point pattern with higher symmetry is characterized by the smaller order metric when their point densities are identical. Order metrics for several other quasiperiodic tilings are also calculated.

The Combined Suture Bridge With Mason-Allen Technique Is Superior to the Conventional Suture Bridge Technique for Arthroscopic Rotator Cuff Repair.

PURPOSE: To compare clinical results and retear rates between the combined suture bridge with Mason-Allen (SBMA) technique and the conventional suture bridge (SB) technique in patients with full-thickness rotator cuff tears who underwent arthroscopic rotator cuff repair. METHODS: One hundred two patients who underwent arthroscopic rotator cuff repair using the SB technique (n = 50) or SBMA technique (n = 52) for a full-thickness rotator cuff tear and had at least 2 years of follow-up were retrospectively analyzed. Magnetic resonance imaging was performed before surgery and 2 years after to determine preoperative tear size, Goutallier stage, and presence of retear after surgery. Patients were clinically evaluated using the Japanese Orthopaedic Association (JOA) score. RESULTS: The groups did not significantly differ in terms of follow-up period, age, sex, tear size, Goutallier stage, or number of suture anchors. The retear rate was significantly lower in the SBMA group (7.7% vs 28.0%; P < .01). The JOA score was significantly higher at last follow-up than before surgery in both groups (P <.01). The JOA score at last follow-up was significantly higher in the SBMA group (P = .02). CONCLUSIONS: Arthroscopic rotator cuff repair using the SBMA technique may provide better clinical and anatomical outcomes than the conventional SB technique. LEVEL OF EVIDENCE: Level III, retrospective cohort design; treatment study).

Shear wave elastography correlates to degeneration and stiffness of the long head of the biceps tendon in patients undergoing tenodesis with arthroscopic shoulder surgery.

BACKGROUND: Tendinopathy of the long head of the biceps (LHB) tendon causes degeneration and changes its stiffness. However, a reliable means of diagnosis has not been established. Shear wave elastography (SWE) provides quantitative tissue elasticity measurements. In this study, the relationship of preoperative SWE values with biomechanically measured stiffness and degeneration of the LHB tendon tissue was investigated. METHODS: LHB tendons were obtained from 18 patients who underwent arthroscopic tenodesis. SWE values were measured preoperatively at 2 sites, proximal to and within the bicipital groove of the LHB tendon. The LHB tendons were detached immediately proximal to the fixed sites and at their superior labrum insertion. Tissue degeneration was histologically quantified using the modified Bonar score. Tendon stiffness was determined using a tensile testing machine. RESULTS: The SWE values of the LHB tendon were 502.1 ± 113.6 kPa proximal to the groove and 439.4 ± 123.3 kPa within the groove. The stiffness was 39.3 ± 19.2 N/mm. The SWE values displayed a moderate positive correlation with the stiffness proximal to the groove (r = 0.80) and within it (r = 0.72). The SWE value of the LHB tendon within the groove showed a moderate negative correlation with the modified Bonar score (r = -0.74). CONCLUSIONS: These findings suggest that preoperative SWE values of the LHB tendon correlate moderately positively with stiffness and moderately negatively with tissue degeneration. Therefore, SWE may predict LHB tendon tissue degeneration and changes in stiffness caused by tendinopathy.

The Effect of Vitamin C and N-Acetylcysteine on Tendon-to-Bone Healing in a Rodent Model of Rotator Cuff Repair.

BACKGROUND: Oxidative stress inhibits tendon-to-bone healing after rotator cuff repair. Regulation of oxidative stress has the potential to accelerate this healing, but its mechanism remains unclear. PURPOSE: To investigate the effects of reducing oxidative stress by applying antioxidants, such as N-acetylcysteine (NAC) and vitamin C (VC), on rotator cuff repair in a rat rotator cuff repair model. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 48 Sprague Dawley rats underwent bilateral surgery to repair the infraspinatus tendon to its insertion site 1 week after detachment. Rats were assigned to either the NAC group, the VC group, or a control group. Histological evaluation was performed via hematoxylin-eosin or toluidine blue staining, and oxidative stress was assessed via dihydroethidium intensity and protein carbonyl concentration at 3 and 6 weeks. Superoxide dismutase 1 (SOD1), SOD2, SOD3, peroxiredoxin 5, collagen type I (COL1), COL3, matrix metalloproteinase 1 (MMP-1), MMP-3, and MMP-13 expression and SOD activity were determined at 3 and 6 weeks. Biomechanical tests were performed at 6 and 12 weeks. RESULTS: Histological evaluation showed that the number of chondrocytes in the NAC group at 6 weeks and in the VC group at 3 and 6 weeks, the area of fibrocartilage at 6 weeks in the VC group, and collagen fibers at 6 weeks in the NAC and VC groups were significantly increased compared with those in the control group. Dihydroethidium intensity at 3 and 6 weeks and protein carbonyls at 6 weeks in the NAC and VC groups were significantly decreased. SOD1 expression and SOD activity at 3 weeks in the VC group and peroxiredoxin 5 expression at 6 weeks in the NAC group were significantly upregulated compared with that in the control group. COL3 expression was significantly upregulated at 6 weeks in the VC group, and MMP-13 expression was significantly decreased at 6 weeks in the NAC and VC groups. The biomechanical strength showed no significant difference. CONCLUSION: Antioxidant treatment, via NAC or VC administration, reduced oxidative stress in the rotator cuff repair site and accelerated healing. CLINICAL RELEVANCE: These findings provide essential indications to develop clinical strategies for improved healing after rotator cuff surgical repair in patients.

Posterior shoulder stiffness was associated with shoulder pain during throwing in college baseball players: assessment of shear wave elastography.

PURPOSE: To investigate shoulder stiffness on the throwing and non-throwing sides in college baseball players using ultrasound shear wave elastography (SWE), and investigate the relationship between stiffness and shoulder pain during throwing. METHODS: Forty-nine college baseball players (98 shoulders) were recruited. Shoulder range of motion was evaluated. SWE was used to measure stiffness of the bilateral supraspinatus tendons, infraspinatus tendons, subscapularis tendons, supraspinatus muscles, infraspinatus muscles (ISPM), and posterior capsules. Participants were divided into pain and no pain groups based on the presence or absence of shoulder pain during throwing within 1 month before measurements on the throwing side. Items were compared between the throwing and non-throwing sides, and between the pain and no pain groups. Factors affecting shoulder pain during throwing were also investigated via multiple logistic regression analysis. RESULTS: Compared with the non-throwing side, the throwing side had significantly greater external rotation at 90° abduction, significantly lesser internal rotation at 0° abduction and internal rotation at 90° abduction (AbdIR), significantly higher SWE values of the infraspinatus tendon, ISPM, and posterior capsule, and significantly lower SWE values of the subscapularis tendon. Compared with the no pain group, the pain group had a significantly higher SWE value of the ISPM, and significantly lesser AbdIR. Increased ISPM SWE values and decreased AbdIR were significantly correlated with shoulder pain during throwing. CONCLUSIONS: The posterior tissue was stiffer than the anterior tissue on the throwing side. Decreased AbdIR and increased ISPM stiffness may be correlated with shoulder pain during throwing.

Anomalous Temperature Dependence of High-Harmonic Generation in Mott Insulators.

We reveal the crucial effect of strong spin-charge coupling on high-harmonic generation (HHG) in Mott insulators. In a system with antiferromagnetic correlations, the HHG signal is drastically enhanced with decreasing temperature, even though the gap increases and the production of charge carriers is suppressed. This anomalous behavior, which has also been observed in recent HHG experiments on Ca_{2}RuO_{4}, originates from a cooperative effect between the spin-charge coupling and the thermal ensemble, as well as the strongly temperature-dependent coherence between charge carriers. We argue that the peculiar temperature dependence of HHG is a generic feature of Mott insulators, which can be controlled via the Coulomb interaction and dimensionality of the system. Our results demonstrate that correlations between different degrees of freedom, which are a characteristic feature of strongly correlated solids, have significant and nontrivial effects on nonlinear optical responses.

Arthroscopic Bankart repair with additional footprint fixation using the double-row technique at the 4 o'clock position anatomically restored the capsulolabral complex and showed good clinical results.

PURPOSE: To investigate the clinical outcome and magnetic resonance imaging (MRI) findings after arthroscopic Bankart repair with additional double anchor footprint fixation (DAFF) at the 4 o'clock position, where the native footprint is widest anatomically, for recurrent anterior shoulder instability. METHODS: Forty-two patients (mean age 27.0 years) with recurrent anterior shoulder instability and without severe glenoid bone defects underwent arthroscopic Bankart repair with additional DAFF at the 4 o'clock position. Using three standard portals, single-row repair was performed at the 2, 3, and 5 o'clock positions, and DAFF with the suture bridging technique was conducted at the 4 o'clock position. MRI was performed preoperatively and at 6 months postoperatively. Patients with follow-up periods of ≥1 year were included in the present study and clinically evaluated at the final follow-up. The morphology at the 2 and 4 o'clock positions on radial MRI slices was compared between the preoperative and 6-month postoperative scans, and the footprint of the repaired capsulolabral complex at 6 months postoperatively was compared between the 2 and 4 o'clock positions. RESULTS: The average follow-up period was 19.5 ± 6.2 months. The rates of dislocation recurrence and positive apprehension test results were 2.4 and 4.8%, respectively. External rotation was restricted by 3.5°. The University of California at Los Angeles and Rowe scores at the final follow-up were 34.5 ± 1.0 points and 97.2 ± 5.7 points, respectively, representing significant improvements over the preoperative scores (p < 0.01). Although the capsulolabral complex at 6 months postoperatively was firmly repaired at both the 2 and 4 o'clock positions compared to its preoperative state, the footprint of the restored capsulolabral complex was wider at the 4 o'clock position than at the 2 o'clock position (p < 0.01). CONCLUSIONS: Additional DAFF at the 4 o'clock position improved the glenohumeral stability and function of the shoulder joint. This study suggests that this technique is a reliable and useful treatment for shoulder instability. LEVEL OF EVIDENCE: IV.

Anatomical position of the corona mortis relative to the anteroposterior and inlet views.

PURPOSE: Although pubic ramus fractures are common in the elderly, resultant hemodynamic instability is a rare complication. The corona mortis, a vascular anastomosis between the obturator vessels and the external iliac vessels in the retropubic space, is occasionally damaged by fractures of the pubic ramus, causing significant hemorrhage. The purpose of this study was to evaluate the incidence and anatomical position of the corona mortis on the anteroposterior and inlet views. METHODS: Sixty-one cadavers (122 hemipelvizes) were dissected and the incidence of the corona mortis was evaluated. Photographs were then taken simulating anteroposterior and inlet radiographs, and labeled as the anteroposterior and inlet views. The distance from the pubic symphysis to the corona mortis was measured on each of the two views. RESULTS: The corona mortis was present in 76.1% of hemipelvizes. The corona mortis traverses along the periosteum of the dorsal surface of the pubis. The incidence of arterial corona mortis was 28.3% and that of venous corona mortis was 76.1%. The distance from the superior margin of the symphysis pubis to the corona mortis measured 47.7 ± 9.9 (45.9-49.6) mm on the anteroposterior view, and 59.4 ± 9.2 (57.3-61.5) mm on the inlet view. CONCLUSIONS: In order to predict possible hemodynamic instability of the corona mortis following pubic ramus fractures, it is of clinical significance to precisely establish the anatomical position of the corona mortis on the anteroposterior and inlet views.

Relationship of superoxide dismutase to rotator cuff injury/tear in a rat model.

Rotator cuff degeneration is one of the several factors that lead to rotator cuff tears. Oxidative stress and superoxide dismutase have been reported to be related to rotator cuff degeneration; however, the precise mechanism still remains unclear. In this study, we investigated the relationship of oxidative stress and superoxide dismutase to the degeneration of the rotator cuff using rat models. Eighty-four rats were used to create a collagenase-induced rotator cuff injury model (injury model) and a rotator cuff tear model (tear model). The controls were administered saline and had only a deltoid incision, respectively. We evaluated degeneration morphology of the rotator cuff using a degeneration score; dihydroethidium fluorescence intensity, which detects oxidative stress; gene expression; and superoxide dismutase activity. The rotator cuffs in the injury and tear models significantly increased degeneration scores and dihydroethidium fluorescence intensity. On the other hand, gene expression of superoxide dismutase isoform, superoxide dismutase 1, and superoxide dismutase activity were significantly decreased in the injury model but showed no significant difference in the tear model. These findings suggested that superoxide dismutase might not be associated with rotator cuff degeneration after tear but may be involved in degenerative rotator cuff without tear. However, we found that rotator cuff degeneration involves oxidative stress both with and without tear. Based on these findings, it is presumed that different treatments may be appropriate, depending on the state of rotator cuff degeneration, because the mechanisms of the degeneration may be different.

Association of Recurrent Tear After Arthroscopic Rotator Cuff Repair and Superoxide-Induced Oxidative Stress.

BACKGROUND: Recurrent tears after arthroscopic rotator cuff repair (ARCR) remain a significant clinical problem. Oxidative stress contributes to the degeneration of the rotator cuff, and a degenerative rotator cuff can lead to recurrent tear after ARCR. However, the correlation between oxidative stress and retear after ARCR is unclear. PURPOSE: To investigate the correlation between superoxide-induced oxidative stress and recurrent tear after ARCR. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A total of 68 patients who underwent ARCR using a suture-bridge technique participated in this study. Specimens were collected from the edge of the torn tendon during surgery. The modified Bonar score was used to evaluate degeneration of the rotator cuff on histological specimens, and fluorescence intensity on dihydroethidium (DHE) staining was used to detect oxidative stress. Superoxide dismutase (SOD) enzyme activity was also measured. The following were used for clinical evaluation: age, tear size on magnetic resonance imaging (MRI) before surgery, Goutallier classification on MRI before surgery, and Japanese Orthopaedic Association score before and 6 months after surgery. After the repaired rotator cuffs were evaluated on MRI 6 months after surgery, the patients were divided into groups: those with a healed rotator cuff (healed group; n = 46) and those with a recurrent tear (retear group; n = 22). The significant differences between the groups were determined with regard to clinical evaluation, modified Bonar score, DHE intensity, and SOD activity. In addition, multivariate logistic regression analysis was performed to investigate risk factors for recurrent tear. RESULTS: Age, tear size, Goutallier classification, modified Bonar score, DHE intensity, and SOD activity were significantly greater in the retear group than in the healed group, although the Japanese Orthopaedic Association score was not significantly different. Multiple logistic regression analysis demonstrated that age, tear size, and SOD activity were significantly correlated with recurrent tear. CONCLUSION: In addition to tear size and age, superoxide-induced oxidative stress may be an exacerbating factor for retear after ARCR.

Stiffness change of the supraspinatus muscle can be detected by magnetic resonance elastography.

Magnetic resonance elastography (MRE) and ultrasound shear wave elastography (SWE) are imaging techniques to measure stiffness of the soft tissue using magnetic resonance imaging (MRI) and ultrasound images, respectively. The purpose of this study was to explore the feasibility of the MRE measurement to evaluate the change in supraspinatus (SSP) muscle stiffness before and after rotator cuff tear, and to compare the result with those of SWE. Six swine shoulders were used. The skin and subcutaneous fat were removed, and the stiffness value of the SSP muscle was measured by MRE and SWE. The MRE measurement was performed with 0.3 T open MRI and the vibration from a pneumatic driver system with active driver to a passive driver to create the shear wave in the tissue. The passive driver was placed on the center of the SSP muscle. The stiffness was estimated from the wave images using local frequency estimation methods. In the SWE measurement, the probe of the ultrasound was placed on the center of the SSP muscle. The shear wave propagation speed was measured at a depth of 1 cm from the surface, and the stiffness was calculated. After those measurements, the rotator cuff tendon was detached from the greater tuberosity, and MRE and SWE measurements were then performed in the same manner again. The differences in the stiffness values were compared between before and after the rotator cuff tendon tear on both the MRE and SWE measurements. The results indicated that stiffness values on MRE and SWE were 9.3 ± 1.8 and 10.0 ± 1.2 kPa respectively before the rotator cuff tear, and 7.3 ± 1.3 and 8.0 ± 0.8 kPa respectively after the tendon detachment. Stiffness values were significantly lower after the tendon detachment on both the MRE and SWE measurements (p < 0.05). Our results demonstrated that stiffness values of the SSP muscle on MRE and SWE were lower after rotator cuff detachment. From this result, MRE may be a feasible method for quantification of the change in rotator cuff muscle stiffness.

Majorana-Mediated Spin Transport in Kitaev Quantum Spin Liquids.

We study the spin transport through the quantum spin liquid (QSL) by investigating the real-time and real-space dynamics of the Kitaev spin system with zigzag edges using the time-dependent Majorana mean-field theory. After the magnetic-field pulse is introduced to one of the edges, spin moments are excited in the opposite edge region although spin moments are never induced in the Kitaev QSL region. This unusual spin transport originates from the fact that the S=1/2 spins are fractionalized into the itinerant and localized Majorana fermions in the Kitaev system. Although both Majorana fermions are excited by the magnetic pulse, only the itinerant ones flow through the bulk regime without spin excitations, resulting in the spin transport in the Kitaev system despite the presence of a nonzero spin gap. We also demonstrate that this phenomenon can be observed in the system with small Heisenberg interactions using the exact diagonalization.

Anatomic Analysis of the Attachment of the Posteroinferior Labrum and Capsule to the Glenoid: A Cadaveric Study.

PURPOSE: To measure the height of the posteroinferior glenohumeral ligament (PIGHL) attachment to the labrum and the depth of the posteroinferior labrum to the glenoid, macroscopically, and to investigate the morphology of the attachment of the posteroinferior labrum to the glenoid, histologically. METHODS: Fifty cadaveric shoulders without exposed subchondral bone on the glenoid and detached posterior labrum were used. We examined the frequency of the heights of the PIGHL attachments to the labrum and the length of the labral attachment on the glenoid rim at the 7, 8, 9, and 10 o'clock positions, macroscopically. According to morphology of the histological labral attachments, it was divided into 3 groups. Labra attached on the articular surface and the glenoid neck were defined as the SN type, while labra attached only to the glenoid neck constituted labra attached to the bone and side of the articular cartilage (Nc type) and labra attached only to bone (Nb type). RESULTS: The PIGHL attached from 7 o'clock to 9 o'clock in 48 shoulders (96%). The mean labral attachment at the 7 o'clock position was 6.3 ± 1.0 mm (range, 4.6-9.4 mm), which was significantly longer than at the other positions (P < .05). Histologically, the frequency of SN type attachment was 49 (98%) shoulders at the 7 o'clock position. CONCLUSIONS: The PIGHL attached between 7 and 9 o'clock in 96% of the shoulders. In 98% of the shoulders, the labrum did not attach to the articular surface, but attached to both the articular cartilage and the bone of the glenoid neck at 7 o'clock. CLINICAL RELEVANCE: The posteroinferior labrum should be repaired widely at the 7 o'clock position and not on the articular surface because the labrum attached anatomically to the glenoid neck.

Quantum phase transitions in the Hubbard model on a triangular lattice.

We investigate the quantum phase transitions in the half-filled Hubbard model on the triangular lattice by means of the path-integral renormalization group method with a new iteration and truncation scheme proposed recently. It is found for a cluster of 36 sites that as the Hubbard interaction U increases, the paramagnetic metallic state undergoes a first-order phase transition to a nonmagnetic insulating (NMI) state at Uc1 approximately 7.4t, which is followed by another first-order transition to a 120 degrees Néel ordered state at Uc2 approximately 9.2t, where t is the transfer integral. The size dependence of the results is also addressed. Our results suggest the existence of the intermediate NMI phase and resolve some controversial arguments on the nature of the previously proposed quantum phase transitions.

Orbital-selective mott transitions in the degenerate Hubbard model.

We investigate the Mott transitions in two-band Hubbard models with different bandwidths. Applying dynamical mean field theory, we discuss the stability of itinerant quasiparticle states in each band. We demonstrate that separate Mott transitions occur at different Coulomb interaction strengths in general, which merge to a single transition only under special conditions. This kind of behavior may be relevant for the physics of the single-layer ruthenates, Ca2-xSrxRuO4.