Subscapularis Tendon Tears: Classification, Diagnosis and Repair

Rotator cuff tears include a panel of tendon lesions, and superior cuff tears are often combined with subscapularis lesions that are more difficult to repair. We propose in this chapter to describe the Lafosse subscapularis tears classification and to describe the arthroscopic repair that can be performed easily with a needle as shuttle. The advantages of these surgical techniques are simplicity, safety and quickness. The procedure is performed under general anaesthesia with the patient in beach chair position. A classic arthroscopic posterior portal is used to perform glenohumeral exploration, and cuff tendons are analysed. Once subscapularis tear is confirmed, the tendon must be released after repair with anterolateral portal. Then, a triple-loaded anchor is positioned at the edge of the bicipital groove to perform both biceps tenodesis and subscapularis repair

Linear Weingarten membranes with funicular boundaries

International audienceDesigning a curved architectural envelope is a challenging task, as it requires a balance between structural efficiency, fabricability and architectural requirements. In this article, we introduce a new conceptual design tool: Linear-Weingarten membranes, with boundaries either simply supported or realized as funicular cables or arches. We present a generation method for these surfaces, with a focus on how to treat free funicular boundaries. The method uses a surface discretization by triangular meshes, and computes a shape iteratively by a combination of dynamic relaxation and guided projections. The method can be used to generate the shape of self-stressed membranes, funicular vaults, and gridshells. For gridshells, the method allows to find geometries that combine mechanical performance and ease of fabrication

Gridshells without kink angle between beams and cladding panels

International audienceIn double-curvature gridshells covered with rigid flat panels, panels cannot lay flat on the top surface of beams. In many cases, costly elements need to be inserted in-between to insure a proper beam-panel connection. Precedent research on the geometric rationalization of gridshells has mostly focused on minimizing cladding panel curvature, simplifying node and beam fabrication, and allowing for repeatability of elements. The connection between beams and panels has received very little attention. This paper explores the possible gridshell geometries under the constraint of having a full planar contact between beams and cladding panels. A strategy that consists of folding panels is studied in details. It turns out that a rich variety of panel shapes and folding patterns is possible. Two generation methods for such shapes are proposed: a method for quad meshes of revolution covered with folded panels, and a method for folded hexagonal panels based on the projection algorithm developed by Bouaziz et al [1]. The resulting structures are of particular interest for opaque doubly curved facades covered with metal sheets or other foldable material. The good contact between beams and panels also offers the possibility to use the panels as bracing elements. Hence the proposed method proves to be efficient for construction purposes, but also for mechanical behavior

Discrete CMC surfaces for doubly-curved building envelopes

International audienceConstant mean curvature surfaces (CMCs) have many interesting properties for use as a form for doubly curved structural envelopes. The discretization of these surfaces has been a focus of research amongst the discrete differential geometry community. Many of the proposed discretizations have remarkable properties for envelope rationalization purposes. However, little attention has been paid to generation methods intended for designers. This paper proposes an extension to CMCs of the method developed by Bobenko, Hoffmann and Springborn (2006) to generate minimal S-isothermic nets. The method takes as input a CMC (smooth or finely triangulated), remeshes its Gauss map with quadrangular faces, and rebuilds a CMC mesh via a parallel transformation. The resulting mesh is S-CMC, a geometric structure discovered by Hoffmann (2010). This type of mesh have planar quads and offset properties, which are of particular interest in the fabrication of gridshells

Caravel meshes: A new geometrical strategy to rationalize curved envelopes

International audienceCurved structural envelopes have been popular in architecture in the past decades. Their main limitation is their high cost, which is due in particular to the manufacturing complexity induced by curvature. This article introduces Caravel meshes, a new family of meshes that offers geometrical properties allowing a significant reduction of fabrication complexity. In particular, for gridshells, the most complicated fabrication aspect is usually the connection between the structural elements-beams and panels. In Caravel meshes, all these connections are rationalized. Beams are connected to panels without kinks, beams are connected top each other with repetitive which are also free of geometrical torsion. We show that a great variety of mesh combinatorics is possible with these properties. We study in particular quadrangular and hexagonal patterns. In each case, we estimate the possible shapes using differential geometry. We show that hexagonal Caravel meshes offer a significant design freedom, such that other geometrical properties simplifying fabrication can be obtained, such as edge offsets. Finally, we show that Caravel meshes offer many new ways to design curved structural systems, in which beams and panels may work together mechanically. We highlight one application for the fast prototyping of curved surfaces

Funicularity of conics

International audienceFunicular structures can resist a given load with pure axial forces, and therefore tend to use material very efficiently. One main challenge in their design is the form-finding, which often requires advanced numerical methods. In this article, we show analytically that a very common family of curves, conics, is funicular for a particular load case: a uniform radial load emanating from a focus (Figure 1). The result is a generalization of the well-known funicularity of parabolas and arcs of circles, respectively under uniform vertical load and constant normal pressure. It can be used to design self-stressed structures by hand without the need for calculations. Portions of conics can be combined to obtain original shapes

Surfaces with planar curvature lines: discretization, generation and application to the rationalization of curved architectural envelopes

International audienceMotivated by architectural applications, we propose a method to generate circular and conical meshes with planar curvature lines in both directions. The method is based on the discretization of the Gauss map of surfaces with planar curvatures lines. It allows generation of meshes in real-time via two planar guide curves. The resulting meshes can be used as a geometric base to build gridshells with flat panels, torsion free-nodes, node offset and planar arches. A particular technological application is for gridshells built with curved members: those can be built with planar piecewise-circular beams, and identical nodes if beams have circular cross-section

Arthroscopic-assisted Acromioclavicular and Coracoclavicular Ligaments Reconstruction for Chronic Acromioclavicular Dislocations

International audienceChronic acromioclavicular (AC) instability is a rare posttraumatic shoulder condition that can lead to undesirable symptoms like persistent pain, muscle fatigue, loss of strength, or even scapular dyskinesis. It is well known that in these cases the superior functional results depend on the restoration of the anatomy and stability of the AC joint in both vertical and horizontal planes. Considering the ligaments degeneration and atrophy in chronic AC joint dislocations, we present an arthroscopic-assisted reconstruction of both the coracoclavicular and AC ligaments using autograft augmentation. In details the coracoclavicular ligaments component is reconstructed using the Tightrope suspension device augmented with a palmaris longus autograft and by the nonanatomic coracoacromial ligament transfer (modified Weaver-Dunn). The AC part is restored by suturing the remainder palmaris longus autograft on the acromion and on the deltotrapezial fascia. Using the construct provided by this technique all the possible ruptured ligaments are reconstructed, optimizing the vertical and horizontal stability of the area, and promising excellent long-term radiologic and functional results

The Caravel heX-Mesh pavilion, illustration of a new strategy for gridshell rationalization

International audienceThe fabrication of a freeform structural envelope is usually a highly complex task. The costliest aspect is often the connections between the constitutive parts. The Caravel heX-Mesh Pavilion is a prototype that demonstrates a new rationalization strategy. Its structure, composed of a hexagonal grid of beams and cladding panels, is based on a geometry that rationalizes connections at two levels: firstly, nodes are free of geometrical torsion and are repetitive: only two types of nodes are used. Secondly, panels can easily be connected to the support beams as they are orthogonal to each other. The mechanical behavior is validated by finite-element analysis. We generate these meshes by numerical optimization from a smooth target surface, with an initialization derived from the asymptotic case and surface theory. The pavilion shows an alternative way of rationalizing a gridshell beyond the popular planar-quad meshes and circular/conical meshes. It also demonstrates a way to generate hexagonal gridshells which are not necessarily synclastic, this limitation being typically imposed to achieve planarity of cladding panels