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La séquence éviter-réduire-compenser a pris une importance croissante dans les politiques environnementales françaises. Mais après plus de dix ans d'application sur le terrain, le constat est partagé : la compensation accapare beaucoup d'efforts, tandis que l'étape de l'évitement est sous-valorisée. À travers l'analyse de dix-huit projets d'infrastructures linéaires en Languedoc-Roussillon, cet article apporte des éclairages sur la pratique actuelle de l'évitement et ses effets réels sur la protection de la biodiversité. Les résultats de l'étude plaident pour l'anticipation et l'intégration de l'évitement dans la planification territoriale.

Citizen sciences are undergoing strong growth, a fact demonstrated by the session devoted to the topic at the 3rd French-language meetings on conservation biology (Le reveil du dodo III, 17-19 March 2009 in Montpellier) and the seminar titled Citizen science and biodiversity, held in Montpellier on 22-23 October 2009. Marion and Frédéric Gosselin, engineer and researcher at Cemagref in Nogent-sur-Vernisson discuss the topic here with Romain Julliard, researcher at the MNHN bird-ringing project and who has managed a number of Vigie-Nature programmes requiring public participation (naturalists and amateurs) to collect the necessary data. The discussion successively addresses the history of citizen sciences, their advantages and limits, focussing on the assessment of biodiversity-conservation policies.

Les sciences participatives connaissent un essor marqué, en témoignent la session qui y a été consacrée aux IIIes Journées francophones de biologie de la conservation (Le réveil du dodo III, 17-19 mars 2009 à Montpellier) et le colloque Sciences citoyennes et biodiversité, tenu à Montpellier les 22-23 octobre 2009. Marion et Frédéric Gosselin, ingénieure et ingénieur-chercheur du Cemagref de Nogent-sur-Vernisson en discutent ici avec Romain Julliard, chercheur au Museum d'histoire naturelle, qui pilote plusieurs programmes fondés sur la participation du public (naturalistes ou amateurs) pour la récolte de données, réunis sous l'appellation Vigie-Nature. Seront successivement abordés l'historique des sciences participatives, leurs avantages et leurs limites d'utilisation, avec un focus sur le cas de l'évaluation des politiques de conservation de la biodiversité.

During replacement of loosened or painful cemented femoral prosthetic stem, the extraction of a large size distal cement plug is rarely an easy matter. To make it simple, quick and safe (no wide surgical exposure, no X-ray exposure) we propose a new technique based upon the perforation of the cement plug by a drill which crosses a jig inserted into the cavity where the femoral stem had been removed. Correctly used the procedure can help the surgeon to solve the difficult problem of removing the femoral cement plug and consequently it can allow the placement of a biomechanically ideal conventional length femoral component into a femur not weakened by a perforation, a fenestration or an osteotomy.

The posterior inclination of the tibial plateaus relative to the longitudinal axis of the bone, also called tibial slope, is important to know for the pathology of the cruciate ligaments and to lay some knee prostheses. We have chosen a reproducible method to measure it, on the basis of a large radiograph of the lower limb. A radio-anatomical analysis of the morphology of the tibia has first been carried out to properly choose axes that are easy to find and useful in practice. The accuracy of the measurement is to within one degree. In adults, the slope ranges from 0 to 18 degrees, according to the subjects, with variations form one knee to the other.

The tibial slope is an important datum in knee surgery; the levelling by a uni- or bicompartmental prosthesis preserving both cruciate ligaments requires to maintain this slope. The postoperative rehabilitation of the A.C.L. plasties, especially those performed with a patellar tendon and the surgical cure of a genu recurvatum, must integrate this notion. Even if the anatomical slopes are usable in prosthetic surgery, they do not seem precise enough in the field of A.C.L. and tibia recurvatum surgery. In these indications, the authors propose to determine the functional tibial slope defined as being the complement of the angle formed by the tangent to the tibial medial plateau and the lateral mechanical axis of the leg. Measured to an average of 7 degrees on 238 knees, the average median functional slope cannot be deduced from anatomical slopes; it must be measured on a lateral teleradiographic view of the lower limb, the knee being in full extension and X-rayed in true posterior and inferior lateral view.

The A.T. T.G.'s scanographic measure sets problems in the major dysplasic trochlear groove because point G.T. is quite impossible to determine. We purpose to define it by an original procedure based on bidimensional reconstruction of A.T. T.G. system. Point G.T. is defined by extrapolation: it is situated at the junction of proximal trochlear scan section with the line representing distal trochlear groove.

The classical X-Ray exploration of the patellar instability is done through incidences performed with knees in a 30 degrees flexion and a 0 degrees rotation. To this basic investigation the authors propose to add original, more physiological incidences performed with knees in external rotation. Because of their extreme sensitiveness, these incidences with a 30 degrees external rotation allow a more accurate diagnosis of the patellar instability (and thereby a better breaking up of the still too nebulous chapter of patellar chrondropathies) and a more critical checking of the surgical centering of the patella. Technically easy to perform they should enter into the usual practice of X-Ray exploration of any mechanical knee.