Traumatische chronische Instabilität des proximalen Tibiofibulargelenkes

Zusammenfassung: Die seltene chronische Instabilität des proximalen Tibiofibulargelenkes kann traumatisch oder idiopatisch auftreten und im Verlauf zur sekundären Arthrose führen. Nach primär konservativer Therapie sollte bei persistierenden Beschwerden nach 6Monaten eine operative Therapie in Betracht gezogen werden. Wir präsentieren den Fall einer traumatischen Instabilität, die Rekonstruktion der Kapsel-Band-Strukturen mit der dorsalen Hälfte der Bizepsfemorissehne und anschließender beschwerdefreier Sportfähigkei

Primordial Earth mantle heterogeneity caused by the Moon-forming giant impact

The giant impact hypothesis for Moon formation successfully explains the dynamic properties of the Earth-Moon system but remains challenged by the similarity of isotopic fingerprints of the terrestrial and lunar mantles. Moreover, recent geochemical evidence suggests that the Earth's mantle preserves ancient (or "primordial") heterogeneity that predates the Moon-forming giant impact. Using a new hydrodynamical method, we here show that Moon-forming giant impacts lead to a stratified starting condition for the evolution of the terrestrial mantle. The upper layer of the Earth is compositionally similar to the disk, out of which the Moon evolves, whereas the lower layer preserves proto-Earth characteristics. As long as this predicted compositional stratification can at least partially be preserved over the subsequent billions of years of Earth mantle convection, the compositional similarity between the Moon and the accessible Earth's mantle is a natural outcome of realistic and high-probability Moon-forming impact scenarios. The preservation of primordial heterogeneity in the modern Earth not only reconciles geochemical constraints but is also consistent with recent geophysical observations. Furthermore, for significant preservation of a proto-Earth reservoir, the bulk composition of the Earth-Moon system may be systematically shifted towards chondritic values.Comment: Comments are welcom

Shoe rim and shoe buckle pseudotumor of the ankle in elite and professional figure skaters and snowboarders: MR imaging findings

Objective: To review MR imaging of figure skaters and snowboarders presenting with painful soft-tissue swelling of the lateral supramalleolar region with a clinical provisional diagnosis of soft-tissue tumor. Design and patients: MR imaging was prospectively reviewed by two sub-specialized musculoskeletal radiologists. The findings were correlated with a second clinical review and examination of the shoe wear. The patients were four female athletes undergoing heavy training regimes, ranging in age between 16 and 25years. Two patients were elite figure skaters, and two were professional snowboarders. Three patients had unilateral masses with pain, and one patient presented with bilateral clinical findings. Results: MR imaging showed subcutaneous, focal soft-tissue masses of the supramalleolar region in five ankles at the same level above the ankle joint. MR imaging prompted a second clinical review and correlation with the shoe wear. The MR imaging findings correlated to the level of the shoe rim or shoe buckle in all patients, confirming the suspected MR imaging diagnosis of an impingement syndrome. All four sportswomen were training excessively, ignoring safety advice regarding training duration, timing of breaks, and shoe wear rotation. Conclusion: Ice skaters and snowboarders may present with persistent and disabling pain. On MR imaging, this corresponds to a focal soft-tissue abnormality, which may be due to subcutaneous fat impingement between the fibula and the shoe rim or shoe buckl

Influence of the bone block position on the tunnel enlargement in ACL reconstruction

Tunnel enlargement can appear after anterior cruciate ligament reconstruction. We investigated the influence of the bone block position of a patellar tendon autograft on the tunnel enlargement in the femur and in the tibia from two aspects. On the one hand, we examined the influence of the tunnel position in respect to the ap-diameter. On the other hand, we examined the influence of the bone block depth in respect to the joint line. In a crossover study over three years, 103 knees with primary ACL reconstruction were included. The incidence of tunnel enlargement measured on X-rays after one year was 52% (n=103) in the femur and 81% (n=103) in the tibia. The average diameter of enlargement was 1.4 mm (14%) in the femur and 2.7 mm (27%) in the tibia. No correlation between the tunnel position and the tunnel enlargement in the sagital plane could be found. However, there is a significant positive correlation between the size of tunnel enlargement and the bone block depth in the femur and in the tibia. There is an average tunnel enlargement of about 0.6 mm (6%) per 10 mm deeper bone plug depth. The relative excess length of the patella tendon favors the development of tunnel enlargement. The effect of the bone block depth on the tunnel enlargement is equal in the femur and the tibia

Thermo-optic noise in coated mirrors for high-precision optical measurements

Thermal fluctuations in the coatings used to make high-reflectors are becoming significant noise sources in precision optical measurements and are particularly relevant to advanced gravitational wave detectors. There are two recognized sources of coating thermal noise, mechanical loss and thermal dissipation. Thermal dissipation causes thermal fluctuations in the coating which produce noise via the thermo-elastic and thermo-refractive mechanisms. We treat these mechanisms coherently, give a correction for finite coating thickness, and evaluate the implications for Advanced LIGO

Optimal Alignment Sensing of a Readout Mode Cleaner Cavity

Critically coupled resonant optical cavities are often used as mode cleaners in optical systems to improve the signal to noise ratio (SNR) of a signal that is encoded as an amplitude modulation of a laser beam. Achieving the best SNR requires maintaining the alignment of the mode cleaner relative to the laser beam on which the signal is encoded. An automatic alignment system which is primarily sensitive to the carrier field component of the beam will not, in general, provide optimal SNR. We present an approach that modifies traditional dither alignment sensing by applying a large amplitude modulation on the signal field, thereby producing error signals that are sensitive to the signal sideband field alignment. When used in conjunction with alignment actuators, this approach can improve the detected SNR; we demonstrate a factor of 3 improvement in the SNR of a kilometer-scale detector of the Laser Interferometer Gravitational-wave Observatory. This approach can be generalized to other types of alignment sensors

Narrow, Fast, and "Cool" Mantle Plumes Caused by Strain-Weakening Rheology in Earth's Lower Mantle

The rheological properties of Earth's lower mantle are key for mantle dynamics and planetary evolution. The main rock-forming minerals in the lower mantle are bridgmanite (Br) and smaller amounts of ferropericlase (Fp). Previous work has suggested that the large differences in viscosity between these minerals greatly affect the bulk rock rheology. The resulting effective rheology becomes highly strain-dependent as weaker Fp minerals become elongated and eventually interconnected. This implies that strain localization may occur in Earth's lower mantle. So far, there have been no studies on global-scale mantle convection in the presence of such strain-weakening (SW) rheology. Here, we present 2D numerical models of thermo-chemical convection in spherical annulus geometry including a new strain-dependent rheology formulation for lower mantle materials, combining rheological weakening and healing terms. We find that SW rheology has several direct and indirect effects on mantle convection. The most notable direct effect is the changing dynamics of weakened plume channels as well as the formation of larger thermochemical piles at the base of the mantle. The weakened plume conduits act as lubrication channels in the mantle and exhibit a lower thermal anomaly. SW rheology also reduces the overall viscosity, notable in terms of increasing convective vigor and core-mantle boundary heat flux. Finally, we put our results into context with existing hypotheses on the style of mantle convection and mixing. Most importantly, we suggest that the new kind of plume dynamics may explain the discrepancy between expected and observed thermal anomalies of deep-seated mantle plumes on Earth

Evidence for melt leakage from the Hawaiian plume above the mantle transition zone

Dehydration reactions at the top of the mantle transition zone (MTZ) can stabilize partial melt in a seismic low-velocity layer (LVL), but the seismic effects of temperature, melt and volatile content are difficult to distinguish. We invert P-to-S receiver function phases converted at the top and bottom of a LVL above the MTZ beneath Hawaii. To separate the thermal and melting related seismic anomalies, we carry out over 10 million rock physics inversions. These inversions account for variations arising from the Clapeyron slope of phase transition, bulk solid composition, dihedral angle, and mantle potential temperature. We use two independent seismic constraints to evaluate the temperature and shear wave speed within the LVL. The thermal anomalies reveal the presence of a hot and seismically slow plume stem surrounded by a “halo” of cold and fast mantle material. In contrast to this temperature distribution, the plume stem contains less than 0.5 vol% melt, while the surrounding LVL—within the coverage area—contains up to 1.7 vol% melt, indicating possible lateral transport of the melt. When compared to the melting temperatures of mantle rocks, the temperature within the LVL, calculated from seismic observations of MTZ thickness, suggests that the observed small degrees of melting are sustained by the presence of volatiles such as CO2 and H2O. We estimate the Hawaiian plume loses up to 1.9 Mt/yr H2O and 10.7 Mt/yr CO2 to the LVL, providing a crucial missing flux for global volatile cycles