La maladie de Legg-Perthes-Calvé (LPC) demeure, malgré les progrès réalisés, une affection difficile et déroutante à traiter. Après un rappel des éléments essentiels de la définition et de ...l'étiologie, de la physiopathologie et des manifestations cliniques, le rôle et la place des investigations complémentaires actuellement à disposition (radiographie, scintigraphie et surtout IRM) sont précisés. Ces examens complémentaires ainsi que leur évolution permettent de mieux cerner le pronostic et, par conséquent, le traitement. Les facteurs importants dans la prise en charge et le pronostic de la maladie de LPC sont : 1) âge du patient, bon pronostic dans la règle sans traitement avant l'âge de cinq ans ; 2) pronostic réservé après l'âge de neuf ans, même après traitement chirurgical ; 3) étendue de la nécrose épiphysaire, en particulier du pilier externe ; 4) excentration de la hanche quel que soit l'âge de l'enfant. Il n'y a toujours pas de traitement causal de cette affection. Les traitements conservateurs et chirurgicaux visent à prévenir l'installation de déformation ou d'« incongruence » articulaire, responsables de coxarthrose dès la quatrième décennie. La place respective des traitements conservateurs et chirurgicaux est analysée ainsi que leurs indications et leurs complications.
Treatment of Legg-Calvé-Perthes disease remains, in spite of realized progresses, difficult and disturbing. The important factors for establishing diagnosis concerning definition, etiology, physiopathology and clinical manifestations are reminded. The role of present complementary investigations as well as their evolution are very important to better establish the prognosis and the treatment. The most important factors for treating and establishing the prognosis of LPC are: 1) age. The prognosis is good in almost every case before 5 years old, without any treatment; 2) the prognosis is not good after 9 years, also, very often, after surgical treatment; 3) area of the epiphyseal necrosis, particularly of the lateral pillar; 4) extrusion of the hip at any age. Today, there is always no causal treatment of Legg-Calvé-Perthes disease. Conservative and surgical treatment aims to prevent deformities of the femoral head accompanied or not by articular incongruency, responsible for hip arthritis from the fourth decade. The place of conservative and surgical treatment as well as their complications are described; it aims to guide the spontaneous recovery with as little as possible, deformation of the femoral epiphysis.
The productivity of the injection moulding process is considerably deteriorated due to the demoulding issues as a result of increasing part and polymer complexity. An effective method to overcome ...some of the issues is the application of coatings on mould surface to reduce adhesion and friction during the moulded part ejection. In such solutions, the mould is coated after the machining by methods such as milling and EDM. In fact, die-sinking EDM is widely used to machine moulds with high accuracy, surface quality and aspect ratios. In this research, a novel method is analysed where the texture of the EDM surface is modulated to achieve desirable surface functionality, leading to reduction of part sticking during ejection in injection moulding. The effect of primary parameters of EDM process on the resulting surface is analysed. It is seen that while the surface amplitude parameters such as Ra and Rz remain similar to the standard eroded surface, the spacing parameter RSm and slope measure RΔq can be modulated. The effect of the surface texture during injection moulding is evaluated by measuring the forces during the ejection stage to characterise part sticking. Similar or considerably reduced ejection forces are observed for the modulated EDM texture compared to the polished surfaces, depending on the polymer type and part geometry. The ejection force observations are correlated to the static and dynamic friction coefficient of surface textures against different polymers. The reduction of ejection forces comparable to the coated surfaces places surface texturing as an effective alternative or a supplement to reduce the demoulding issues and thus increasing the injection moulding productivity and part quality.
The problem of high melt viscosity of thermoplastics can be solved by using cyclic butylene terephthalate (CBT), a low viscous prepolymer that polymerizes to the thermoplastic ...polybutyleneterephthalate (PBT). If CBT polymerizes isothermally, big perfect crystals can grow, which induces brittleness. To solve this problem, CBT is mixed with polycaprolactone (PCL). CBT and PCL will form a copolymer, which leads to a much tougher material, both for unfilled material and for composites. The samples are tested under tensile, bending and impact loading. The increased toughness is due to the lower crystallinity, induced by the copolymerization, which is assessed by a DSC-test.
Compression, tension and torsion tests were designed and completed successfully on a brushite and a precipitated hydroxyapatite cement in moist condition. Elastic and strength properties were ...measured for these three loading cases. For each cement, the full set of strength data was fitted to an isotropic Tsai–Wu criterion and the associated coefficients identified. Since the compressive Young's moduli were about 10% larger than the tensile moduli, the full set of elastic data of each cement was fitted to a conewise linear elastic model. Hysteresis of the stress-strain curves was also observed, indicating dissipation mechanisms within these cement microstructures. A comparison of the measured mechanical properties with human cancellous bone confirmed the indication of brushite as a bone filling material and the potential of the hydroxyapatite cement as a structural biomaterial.
Legg-Calve-Perthes disease Dutoit, M
Archives de pédiatrie : organe officiel de la Société française de pédiatrie
14, Številka:
1
Journal Article
Recenzirano
Treatment of Legg-Calvé-Perthes disease remains, in spite of realized progresses, difficult and disturbing. The important factors for establishing diagnosis concerning definition, etiology, ...physiopathology and clinical manifestations are reminded. The role of present complementary investigations as well as their evolution are very important to better establish the prognosis and the treatment. The most important factors for treating and establishing the prognosis of LPC are: 1) age. The prognosis is good in almost every case before 5 years old, without any treatment; 2) the prognosis is not good after 9 years, also, very often, after surgical treatment; 3) area of the epiphyseal necrosis, particularly of the lateral pillar; 4) extrusion of the hip at any age. Today, there is always no causal treatment of Legg-Calvé-Perthes disease. Conservative and surgical treatment aims to prevent deformities of the femoral head accompanied or not by articular incongruency, responsible for hip arthritis from the fourth decade. The place of conservative and surgical treatment as well as their complications are described; it aims to guide the spontaneous recovery with as little as possible, deformation of the femoral epiphysis.
The purpose of this paper is to discuss the post-traumatic overload syndrome of the os trigonum as a possible cause of posterior ankle impingement and hindfoot pain. We have reviewed 19 athletes who ...were referred to our foot unit between 1995 and 2001 because of posterior ankle pain, and in whom a post-traumatic overload syndrome of os trigonum was diagnosed. All these patients were followed up over a period of 2 years. In 11 cases a chronic repetitive movements in forced plantar flexion was found. In the other eight cases the pain appeared to persist after a standard treatment of an ankle sprain in inversion plantar flexion. The diagnosis was based on clinical history, physical examination and X-rays that revealed a non-fused os trigonum. The confirmation of diagnosis was carried-out injecting local anaesthetic under fluoroscopic control. In all cases a corticosteroid injection as first line treatment was performed. In 6 cases a second injection was necessary to alleviate pain because incomplete recovery with the first injection. Three cases (16%) were recalcitrant to this treatment and in these three cases a surgical excision of the os trigonum was carried out. Our conclusion is that after some chronic athletic activity or an acute ankle sprain the os trigonum, if present, may undergo mechanical overload, remain undisrupted and become painful. Treatment by corticosteroid injection often resolves the problem.
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