The release of adhesions improves outcome following minimally invasive repair of Achilles tendon rupture

Purpose Operative repair of Achilles tendon rupture may lead to complications, which influence outcome adversely. The aim of this study was to determine the incidence, impact and response to treatment of post-operative adhesions. Methods From February 2009 to 2021, 248 patients operated on with percutaneous or minimally invasive surgical repair have been prospectively evaluated using the Achilles tendon Total Rupture Score (ATRS) and Heel-Rise Height Index (HRHI), following acute Achilles tendon rupture. Results Fourteen (5.6%) patients were identified as having adhesions. Four patients reported superficial adhesions and ten patients reported a deeper tightness of the tendon. At a mean (SD) of 10.5 (2.3) months following repair, the overall ATRS was at a median (IQR) 65 (44.5–78) points and (HRHI) was mean (SD) 81.5 (13.5)%. Of those deemed to have deep adhesions the antero-posterior diameter of the tendon was at mean (SD) 15.6 (4.6) mm. Open release of superficial adhesions resulted in improved ATRS in all patients. Endoscopic debridement anterior to the Achilles tendon led to alleviation of symptoms of tightness and discomfort from deep adhesions and improved outcome in terms of the ATRS score. At a mean (SD) of 15.9 (3.3)-month follow-up from initial rupture and repair, the patients reported at median (IQR) ATRS scores of 85 (64.8–92.8) points, Tegner level 5 (3–9) and mean (SD) HRHI 86.2 (9.5)%. Patients significantly improved both ATRS and HRHI following release at median (IQR) of 16.5 (− 1.8–29.3) points (p = 0.041) and mean (SD) 5.6 (8.3)% (p = 0.043). Conclusions The incidence of patient-reported adhesions following minimally invasive repair of Achilles tendon rupture was estimated to be 5.6%. The occurrence of superficial adhesions was associated with a lower outcome scores as well as symptoms of anterior tendon tightness and stiffness were associated with a lower score in most patients. Surgical release of adhesions led to a significant improvement in outcome.

The Doctrine of Exile in Kabbalah

Exile (galut)—and the attempt to end it—is one of primary aims and motifs of Jewish mysticism and Kabbalah. Kabbalists have conceived of exile as the existential state of man (the divine soul trapped in the body), the predicament and mission of the Jewish people (banished from Israel), and, most dramatically, the current condition of God and the cosmos. Classic kabbalistic works, such as the Zohar, explain that man’s original sin caused the initial rupture within God, while humanity’s ongoing transgressions increasingly intensify it. Since the earliest kabbalistic writings, in the twelfth century, and continuing until today, numerous Kabbalists have boldly asserted that the primary purpose of both the Torah and man’s deeds is to mend these fractures by unifying the male and female aspects of God, raising the dispersed divine sparks, and elevating man’s dislocated soul. Through these mystical processes, the exile will draw to a close, ushering in the messianic age.

Focal Mechanism and Seismogenic Structure of the MS 5.1 Qingbaijiang Earthquake on February 3, 2020, Southwestern China

The 3 February 2020 MS 5.1 Qingbaijiang earthquake, southwestern China, is the closest recorded MS ≥ 5.0 event to downtown Chengdu City to date, with an epicentral distance of only 38 km. Here we analyze seismic data from the Sichuan and Chengdu regional seismic networks, and employ a multi-stage location method to relocate the earthquakes that have occurred along the central and northern segments of the Longquanshan fault zone since 2009, including the MS 5.1 Qingbaijiang earthquake sequence, to investigate the seismogenic structure of the region. The relocation results indicate that the seismicity along the central and northern segments of the Longquanshan fault zone has occurred mainly along the eastern branch since 2009, with the hypocentral distribution along a vertical cross-section illustrating a steep, NW-dipping parallel imbricate structure. The terminating depth of the eastern branch is about 12 km. The distribution of the MS 5.1 Qingbaijiang earthquake sequence is along the NE–SW-striking Longquanshan fault zone. The aftershock focal depths are in the 3–6 km range, with the mainshock located at 104.475°E, 30.73°N. Its initial rupture depth of 5.2 km indicates that the earthquake occurred above the shallow decollement layer of the upper crust in this region. The hypocentral distribution along the long axis of the aftershock area highlights that this earthquake sequence occurred along a fault dipping at 56° to the NW. Our surface projection of the inferred fault plane places it near the eastern branch of the Longquanshan fault zone. We infer the MS 5.1 mainshock to be a thrust faulting event based on the focal mechanism solution via the cut-and-paste waveform inversion method, with strike/dip/rake parameters of 22°/36°/91° and 200°/54°/89° obtained for nodal planes I and II, respectively. We identify that the seismogenic fault of the MS 5.1 Qingbaijiang earthquake lies along the eastern branch of the Longquanshan fault zone, and nodal plane II represents the coseismic rupture plane, based on a joint analysis of the event relocation results, mainshock focal mechanism, and regional geological information. Our study provides vital information for assessing the seismic hazard of the Longquanshan fault zone near Chengdu City.

First-Motion Focal Mechanism Solutions for 2015–2019 M ≥ 4.0 Italian Earthquakes

A list of 100 focal mechanism solutions that occurred in Italy between 2015 and 2019 has been compiled for earthquakes with magnitude M ≥ 4.0. We define earthquake parameters for additional 22 seismic events with 3.0 ≤ M < 4.0 for two specific key zones: Muccia, at the northern termination of the Amatrice–Visso–Norcia 2016–2018 central Italy seismic sequence, and Montecilfone (southern Italy) struck in 2018 by a deep, strike-slip Mw 5.1 earthquake apparently anomalous for the southern Apennines extensional belt. First-motion focal mechanism solutions are a good proxy for the initial rupture and they provide important additional information on the source mechanism. The catalog compiled in the present paper provides earthquake parameters for individual events of interest to contribute, as a valuable source of information, for further studies as seismotectonic investigations and stress distribution maps. We calculated the focal mechanisms using as a reference the phase pickings reported in the Italian Seismic Bulletin (BSI). We visually checked the reference picks to accurately revise manual first-motion polarities, or include new onsets when they are not present in the BSI dataset, for the selected earthquakes within the whole Italian region, with a separate focus on the Amatrice–Visso–Norcia seismic sequence area from August 24, 2016 to August 24, 2018. For the Montecilfone area, we combined the information on the geometry and kinematics of the source of the 2018 Mw 5.1 event obtained in this study with available subsurface and structural data on the Outer Apulia Carbonate Platform to improve understanding of this intriguing strike-slip sequence. Our analysis suggests that the Montecilfone earthquake ruptured a W–E trending strike-slip dextral fault. This structure is confined within the Apulia crystalline crust and it might represent the western prolongation of the Mattinata Fault–Apricena Fault active and seismogenic structures. The calculated focal mechanisms of the entire catalog are of good quality complementing important details on source mechanics from moment tensors and confirming the relevance of systematically including manually revised and more accurate polarity data within the BSI database.

Cascading earthquakes on a fracture network in a geo-energy reservoir

<p>The increasing rate of induced seismicity in subsurface reservoirs, exceeding occasionally moment magnitude 5, has generated significant attention among earthquake scientists and regulators over the last decade. Fluid injection activity during the operation stage often produces a significant, sometimes even destructive, earthquake. Many approaches have been proposed to monitor, model, and predict the injection-related seismicity to avoid an earthquake larger than a threshold set by the regulator (e.g., Mw 2.0). However, unexpected higher magnitude events occur exceeding what is predicted by empirical models, theoretical relations, or computer simulations. </p><p>Current models do not consider that subsurface reservoirs consist of complex fracture networks characterized by connected and unconnected individual fracture planes, often comprising a larger but inactive fault (unfavorably oriented with respect to regional stress). Fluid injection may then perturb stress conditions and trigger an initial rupture on fractures close to the injection well; this initial event may then dynamically trigger other fractures and potentially generate a large earthquake. </p><p>We inspect conditions leading to induced earthquakes taking into account the complex fracture network intersected to an inactive fault using dynamic earthquake rupture simulations. We generate the fracture network using a nearest-neighbor method following statistical parameters (power-law distribution of fracture length and fracture density) based on field data. There are 134 fractures consisting of 95 connected fractures, 3 fractures connected with at least one fracture, and 38 unconnected fractures. We focus on two fracture populations oriented in strike N110E ± 10° and N210E ± 10°, respectively. The main fault has a depth-dependent dip orientation which results in a listric fault geometry. </p><p>For our dynamic rupture simulations, we use the open-source software SeisSol (https://github.com/SeisSol/SeisSol), apply a laboratory-based rate-and-state with rapid velocity weakening friction law, and assign source radius-dependent characteristic length (L parameter) to the fractures. We vary stress conditions (maximum horizontal orientation, static-pore pressure, and prestress ratio) and conduct an initial static Mohr-Coulomb analysis before running the expensive dynamic rupture simulation. We choose conditions that lead to cascading rupture with (case 1) and without (case 2) the involvement of the main fault. Case 1 has higher artificial overstress within the nucleation area than case 2. Our simulation shows intricate rupture progression over small fractures via rupture branching with the parallel and orthogonal connected fractures. The rupture can also transfer to the unconnected fractures through dynamic triggering from the closest neighboring fracture. Case 1 produces a moment magnitude of Mw 6.36 that is equivalent to case 2. Our preliminary result reveals that connected fractures can generate a significant and potentially large induced earthquake if all fractures are favorable to the stress condition.</p>

Deep structure of the Atlantic margins and neighboring oceanic crust from wide-angle seismic data and plate kinematic reconstructions.

<p>In order to study opening mechanisms and their variation in the Atlantic ocean basins, we compiled existing wide-angle and deep seismic data along conjugate margins and performed plate tectonic reconstructions of the original opening geometries to define conjugate margin pairs. A total of 23 published wide-angle seismic profiles from the different margins of the Atlantic basin were digitized, and reconstructions at break-up and during early stages of opening were performed. Main objectives were to understand how magma-rich and magma-poor margins develop and to define more precisely the role of geologic inheritance (i.e., preexisting structures) in the break-up phase. At magma-poor margins, a phase of tectonic opening without accretion of a typical oceanic crust often follows initial rupture, leading to exhumation of serpentinized upper mantle material. Along volcanic margins the first oceanic crust can be overthickened, and both over- and underlain by volcanic products. The first proto-oceanic crust is often accreted at slow to very slow rates, and is thus of varied thickness, mantle content and volcanic overprint. Accretion of oceanic crust at slow to very slow spreading rates can also be highly asymmetric, so the proto oceanic crust at each side of conjugate margin pairs can differ. Another major aim of this study was to understand the mechanisms of formation and origins of transform marginal plateaus. These are bathymetric highs located at the border of two ocean basins of different ages and are mostly characterized by one or several volcanic phase during their formation. They often form conjugate pairs along a transform margin as it evolves and might have been the last land bridges during breakup, thereby influencing mammal migration and proto-oceanic currents in very young basins. At these plateaus, volcanic eruptions can lead to deposits of (at least in part subaerial) lava flows several km thick, better known by their geophysical signature as seaward dipping reflectors. Continental crust, if present, is heavily modified by volcanic intrusions. These marginal plateaus might form when rifting stops at barriers introduced by the transform margin, leading to the accumulation of heat in the mantle and increased volcanism directly before or after the cessation of rifting.</p>

Source Characteristics of the 2020 Mw 7.4 Oaxaca, Mexico, Earthquake Estimated from GPS, InSAR, and Teleseismic Waveforms

On 23 June 2020, an Mw 7.4 earthquake struck offshore Oaxaca, Mexico, providing a unique opportunity to understand the seismogenic tectonics of the Mexican subduction zone. In this study, near-field coseismic deformation caused by the event was retrieved from Global Positioning System (GPS) observations and Interferometric Synthetic Aperture Radar (InSAR) measurements. Given static geodetic measurements, high-rate GPS waveforms, and teleseismic waveforms, the fault geometry and rupture process for the 2020 Oaxaca earthquake were robustly determined by nonlinear joint inversions. The main slip was located at a depth of 20–30 km with a peak slip of 3.4 m near the epicenter. The total released moment was 1.70×1020 N·m, corresponding to Mw 7.4. The whole rupture process lasted 14 s, with the dominant rupture slip occurring 5–8 s after initial rupture. The mainshock rupture mostly occurred along the fault strike, covering a size of ∼55 km(along strike)×∼35 km(along dip) and totally overlapping with the 1965 Mw 7.5 rupture zone. We speculate that this 2020 earthquake is a repeat event following that in 1965. Fluid percolation under the slab may be one of the key factors affecting the seismogenic depth in the Oaxaca region.

Estimating the Areas of High-Frequency Wave Radiation on the Fault Plane of the 2008 Mw 7.9 Wenchuan, China, Earthquake by Envelope Inversion

ABSTRACT We estimated the areas exhibiting high-frequency (1∼10 Hz) wave radiation on the fault plane of the 2008 Wenchuan earthquake, by applying envelope inversion to strong-motion acceleration records. The corrected records of two small earthquakes are adopted as the empirical Green’s functions. Considering the change in the rupture pattern of the Wenchuan earthquake from southwest to northeast, the records of small earthquakes dominated by thrust and strike-slip are utilized as the empirical Green’s function for the southwestern and northeastern fault sections, respectively. The results are as follows: (1) According to the high-frequency wave radiation, the rupture process is complex. High-frequency waves radiated strongly in six areas: around the initial rupture point, along the north and south edges of the fault plane, near the area of intersection with the cross-cutting Xiaoyudong fault, south of Nanba, and near the area of Qingchuan. In total, these areas can be divided into three cases. In the first situation, high-frequency waves radiated strongly around the initial rupture area, which may be associated with the initiation of rupture and a high stress drop. The second location is near the periphery of the fault, which is associated with the termination of rupture. The third condition comprises high-frequency waves near the intersection with the cross-cutting Xiaoyudong fault. This area as a geometric barrier, and the surface rupture is observed. (2) The distribution patterns of the high- and low-frequency radiation intensity differ on the fault plane. From the hypocenter to the point of intersection with the Xiaoyudong fault, the high-frequency wave is located around the area with large slip value. In other areas, the distribution of the high- and low-frequency radiation is no obvious relationship. This different characteristic indicates the complexity of the rupture process.

Investigation for Influences of Seepage on Mechanical Properties of Rocks Using Acoustic Emission Technique

The behavior of rock mass is governed by the properties of both the rock material and discontinuities in the rock mass. Surrounding environments including the existence of water also have a great influence on the behavior and mechanical properties of rocks. In this study, a novel-designed compression and seepage testing system, associated with an acoustic emission system, was designed and constructed. The changes in the specimens resulting from the uniaxial compression were monitored by an acoustic emission technique. The characteristics of the acoustic emission parameters at different stages including compaction and crack initiation, crack propagation, and catastrophic failure were analyzed. The existence of seepage had direct influences on the mechanical properties and failure patterns of the specimens. The specimens tested in pure compression conditions demonstrated strong burst proneness and ruptured into separate pieces, while for the specimens with seepage, no burst proneness was observed and the specimens tended to fail along a macroscopic shear failure plane. The highest average energy of the acoustic signal occurred at the stage of initial rupture of rock specimens, rather than at the stage of widespread rupture. The studies explored the possibilities of using the acoustic emission technique to investigate the problems associated with the seepage in geotechnical and rock engineering and provided meaningful results for further research in this field.

Shape and Dimension Estimations of Landslide Rupture Zones via Correlations of Characteristic Parameters

For many geotechnical purposes, the proper estimation of shapes and dimensions of landslide rupture zones is of significant importance. Very often, this exact delineation is difficult due to the lack of information on rupture zone extents in 3D. Based on a global landslide inventory, this work presents statistical analyses correlating dimension-related and shape-related parameters characterizing a rupture zone in 3D to its volume. Dimension-related parameters are approximated by linear regressions increasing with greater volumes, whereas shape-related parameters appear stable throughout the entire range of volumes. Revealing themselves as very stable, these correlations can be used, hence, to extrapolate from a distinct parameter to the volume of a landslide rupture zone. In a second stage, ratios of dimension-related parameters are correlated with rupture zone volumes. Furthermore, this type of correlation delivers very stable results showing that ratios are constant throughout the entire range of volumes. Making use of this ratio consistency, it is possible to deduce one of the two parameters when the other one is given. This latter aspect seems to be promising for remote sensing surveys when initial rupture areas or rupture volumes should be delineated or for numerical modeling of landslides in 3D.