Tibial Tubercle Osteotomy and Medial Patellofemoral Ligament Imbrication for Patellar Instability Due to Trochlear Dysplasia.

BackgroundThe treatment of patellar instability in the setting of trochlear dysplasia is challenging.Purpose/hypothesisThe purpose of this study was to evaluate outcomes for the treatment of recurrent patellar dislocations due to trochlear dysplasia using anteromedialization tibial tubercle osteotomy combined with medial patellofemoral ligament (MPFL) imbrication. We hypothesized that the treatment of patellar instability with tibial tubercle osteotomy and MPFL imbrication would result in improved patient satisfaction and decrease patellar instability events in patients with prior instability and trochlear dysplasia.Study designCase series; Level of evidence, 4.MethodsWe performed a retrospective analysis of patients who underwent MPFL imbrication and concomitant anteromedialization tibial tubercle osteotomy for recurrent patellofemoral instability at a single institution. The minimum follow-up was 1 year. Patient demographic information including age at the time of surgery, sex, body mass index (BMI), tibial tubercle-trochlear groove (TT-TG) distance, and grade of trochlear dysplasia was collected along with relevant operative data. Postoperatively, recurrent dislocation events as well as Knee injury and Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster Universities Osteoarthritis Index, and Kujala scores were collected, and satisfaction was ascertained by asking patients whether they would undergo the procedure again.ResultsA total of 37 knees from 31 patients (23 female) with a mean follow-up of 3.8 years (range, 1-8.9 years) were included. The mean patient age was 28.8 years (range, 14-45 years), the mean BMI was 24 kg/m2 (range, 20-38 kg/m2), and the mean preoperative TT-TG distance was 18.9 mm (range, 8.4-32.4 mm). Two knees were classified as low-grade trochlear dysplasia (Dejour A) and 35 as high-grade trochlear dysplasia (Dejour B-D). At final follow-up, patients reported mean KOOS subscale scores of 86.5 (Pain), 79.8 (Symptoms), 93.9 (Activities of Daily Living), 74.3 (Sports/Recreation), and 61.9 (Quality of Life), as well as a mean Kujala score of 81.3. Mean patient satisfaction was 8.3 of 10. The majority of knees (86.5%; 32/37) remained stable without recurrent instability after this procedure, while 13.5% (5 knees) suffered a recurrent dislocation, with 2 requiring revision surgery. Eight knees (21.6%) underwent subsequent hardware removal.ConclusionAnteromedialization tibial tubercle osteotomy with MPFL imbrication can improve recurrent patellofemoral instability and provide significant clinical benefit to patients with trochlear dysplasia

Submillimeter diffusion tensor imaging and late gadolinium enhancement cardiovascular magnetic resonance of chronic myocardial infarction.

BackgroundKnowledge of the three-dimensional (3D) infarct structure and fiber orientation remodeling is essential for complete understanding of infarct pathophysiology and post-infarction electromechanical functioning of the heart. Accurate imaging of infarct microstructure necessitates imaging techniques that produce high image spatial resolution and high signal-to-noise ratio (SNR). The aim of this study is to provide detailed reconstruction of 3D chronic infarcts in order to characterize the infarct microstructural remodeling in porcine and human hearts.MethodsWe employed a customized diffusion tensor imaging (DTI) technique in conjunction with late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) on a 3T clinical scanner to image, at submillimeter resolution, myofiber orientation and scar structure in eight chronically infarcted porcine hearts ex vivo. Systematic quantification of local microstructure was performed and the chronic infarct remodeling was characterized at different levels of wall thickness and scar transmurality. Further, a human heart with myocardial infarction was imaged using the same DTI sequence.ResultsThe SNR of non-diffusion-weighted images was >100 in the infarcted and control hearts. Mean diffusivity and fractional anisotropy (FA) demonstrated a 43% increase, and a 35% decrease respectively, inside the scar tissue. Despite this, the majority of the scar showed anisotropic structure with FA higher than an isotropic liquid. The analysis revealed that the primary eigenvector orientation at the infarcted wall on average followed the pattern of original fiber orientation (imbrication angle mean: 1.96 ± 11.03° vs. 0.84 ± 1.47°, p = 0.61, and inclination angle range: 111.0 ± 10.7° vs. 112.5 ± 6.8°, p = 0.61, infarcted/control wall), but at a higher transmural gradient of inclination angle that increased with scar transmurality (r = 0.36) and the inverse of wall thickness (r = 0.59). Further, the infarcted wall exhibited a significant increase in both the proportion of left-handed epicardial eigenvectors, and in the angle incoherency. The infarcted human heart demonstrated preservation of primary eigenvector orientation at the thinned region of infarct, consistent with the findings in the porcine hearts.ConclusionsThe application of high-resolution DTI and LGE-CMR revealed the detailed organization of anisotropic infarct structure at a chronic state. This information enhances our understanding of chronic post-infarction remodeling in large animal and human hearts

LVMB manifolds and simplicial spheres

LVM and LVMB manifolds are a large family of examples of non kahler manifolds. For instance, Hopf manifolds and Calabi-Eckmann manifolds can be seen as LVMB manifolds. The LVM manifolds have a very natural action of the real torus and the quotient of this action is a simple polytope. This quotient allows us to relate closely LVM manifolds to the moment-angle manifolds studied (for example) by Buchstaber and Panov. The aim of this paper is to generalize the polytopes associated to LVM manifolds to the LVMB case and study its properties. In particular, we show that it belongs to a very large class of simplicial spheres. Moreover, we show that for every sphere belonging to this class, we can construct a LMVB manifold whose associated sphere is the given sphere. We use this latter result to show that many moment-angle complexes can be endowed with a complex structure (up to product with circles)

Polygons vs. clumps of discs: a numerical study of the influence of grain shape on the mechanical behaviour of granular materials

We performed a series of numerical vertical compression tests on assemblies of 2D granular material using a Discrete Element code and studied the results with regard to the grain shape. The samples consist of 5,000 grains made from either 3 overlapping discs (clumps - grains with concavities) or six-edged polygons (convex grains). These two grain type have similar external envelopes, which is a function of a geometrical parameter $\alpha$. In this paper, the numerical procedure applied is briefly presented followed by the description of the granular model used. Observations and mechanical analysis of dense and loose granular assemblies under isotropic loading are made. The mechanical response of our numerical granular samples is studied in the framework of the classical vertical compression test with constant lateral stress (biaxial test). The comparison of macroscopic responses of dense and loose samples with various grain shapes shows that when $\alpha$ is considered a concavity parameter, it is therefore a relevant variable for increasing mechanical performances of dense samples. When $\alpha$ is considered an envelope deviation from perfect sphericity, it can control mechanical performances for large strains. Finally, we present some remarks concerning the kinematics of the deformed samples: while some polygon samples subjected to a vertical compression present large damage zones (any polygon shape), dense samples made of clumps always exhibit thin reflecting shear bands. This paper was written as part of a CEGEO research project www.granuloscience.comComment: This version of the paper doesn't include figures. Visit the journal web site to download the final version of the paper with the figure

Architecture of orogenic belts and convergent zones in Western Ishtar Terra, Venus

Linear mountain belts in Ishtar Terra were recognized from Pioneer-Venus topography, and later Arecibo images showed banded terrain interpreted to represent folds. Subsequent analyses showed that the mountains represented orogenic belts, and that each had somewhat different features and characteristics. Orogenic belts are regions of focused shortening and compressional deformation and thus provide evidence for the nature of such deformation, processes of crustal thickening (brittle, ductile), and processes of crustal loss. Such information is important in understanding the nature of convergent zones on Venus (underthrusting, imbrication, subduction), the implications for rates of crustal recycling, and the nature of environments of melting and petrogenesis. The basic elements of four convergent zones and orogenic belts in western Ishtar Terra are identified and examined, and then assess the architecture of these zones (the manner in which the elements are arrayed), and their relationships. The basic nomenclature of the convergent zones is shown

Sedimentary processes and architecture of Upper Cretaceous deep-sea channel deposits : a case from the Skole Nappe, Polish Outer Carpathians

Deep-sea channels are one of the architectonic elements, forming the main conduits for sand and gravel material in the turbidite depositional systems. Deep-sea channel facies are mostly represented by stacking of thick-bedded massive sandstones with abundant coarse-grained material, ripped-up clasts, amalgamation and large scale erosional structures. The Manasterz Quarry of the Ropianka Formation (Upper Cretaceous, Skole Nappe, Carpathians) contains a succession of at least 31 m of thick-bedded high-density turbidites alternated with clast-rich sandy debrites, which are interpreted as axial deposits of a deep-sea channel. The section studied includes 5 or 6 storeys with debrite basal lag deposits covered by amalgamated turbidite fills. The thickness of particular storeys varies from 2.5 to 13 m. Vertical stacking of similar facies through the whole thickness of the section suggest a hierarchically higher channel-fill or a channel complex set, with an aggradation rate higher than its lateral migration. Such channel axis facies cannot aggrade without simultaneous aggradation of levee confinement, which was distinguished in an associated section located to the NW from the Manasterz Quarry. Lateral offset of channel axis facies into channel margin or channel levee facies is estimated at less than 800 m. The Manasterz Quarry section represents mostly the filling and amalgamation stage of channel formation. The described channel architectural elements of the Ropianka Formation are located within the so-called Łańcut Channel Zone, which was previously thought to be Oligocene but may have been present already in the Late Cretaceous

Selling the Bird : Richard Walton Tully´s the bird of paradise and the dynamics of theatrical commodification

The subject of this essay is a largely forgotten long-run play that had considerable impact on US culture in the first half of the twentieth century. Richard Walton Tully´s romantic drama "The Bird of Paradise" is a perfect example of a serious-minded, commercially successful play that has been erased from our disciplinary memory

Playing simplicity: polemical stupidity in the writing of the French Enlightenment

Polemical stupidity - a critical concept drawn from Bakhtin – denotes the strategic refusal to understand. It appears most familiarly in the character of the Fool (like Candide), who genuinely does not understand the world, thus unmasking its incoherence. But in literature it can cover too the stance of the narrator or author (who pretends to misunderstand). It also functions at the levels of genre and style, embracing parody and rewriting in general. It is a dialogic or open form of critical engagement. Though it can be found throughout Western literature, polemical stupidity is most richly characteristic of the writing of the French Enlightenment. This book suggests why, and traces its rise and fall as a discursive practice in the century from Pascal to Rousseau. Early chapters consider the concept itself, its emergence in Pascal's ‘Lettres provinciales’, worldliness and unworldliness, and the new writing of 1660-1700 (critical history to fairy tales). The main part of the book, on the age of Enlightenment itself, contains successive chapters on Regency theatre, Montesquieu's ‘Lettres persanes’, Marivaux, Voltaire, Diderot, and finally Rousseau who will not play

The Tikopia and “What Raymond Said”

I collected information for another version of a Tikopia fifty years on from Firth's first visit, I spoke to women and gained new insights from a paradigm undreamed in 1929. Then I wrote a thesis in a manner appropriate to my status in the discipline because, according to Paul Rabinow, one cannot be experimental without tenure. After that my representation of the Tikopia engaged with the symbolic and reflexive, seeking a voice to describe my perceptions of Tikopia. But under my voice was an imbrication of voices: Firth's, the Tikopia's, the Tikopia quoting Firth, and a discipline trying hard to get it right