A musculoskeletal shoulder model based on pseudo-inverse and null-space optimization.

The goal of the present work was assess the feasibility of using a pseudo-inverse and null-space optimization approach in the modeling of the shoulder biomechanics. The method was applied to a simplified musculoskeletal shoulder model. The mechanical system consisted in the arm, and the external forces were the arm weight, 6 scapulo-humeral muscles and the reaction at the glenohumeral joint, which was considered as a spherical joint. The muscle wrapping was considered around the humeral head assumed spherical. The dynamical equations were solved in a Lagrangian approach. The mathematical redundancy of the mechanical system was solved in two steps: a pseudo-inverse optimization to minimize the square of the muscle stress and a null-space optimization to restrict the muscle force to physiological limits. Several movements were simulated. The mathematical and numerical aspects of the constrained redundancy problem were efficiently solved by the proposed method. The prediction of muscle moment arms was consistent with cadaveric measurements and the joint reaction force was consistent with in vivo measurements. This preliminary work demonstrated that the developed algorithm has a great potential for more complex musculoskeletal modeling of the shoulder joint. In particular it could be further applied to a non-spherical joint model, allowing for the natural translation of the humeral head in the glenoid fossa.

Non-remboursement de la fécondation in vitro : il est temps de changer d'avis

La fécondation in vitro (FIV) n'est pas remboursée. Le Tribunal fédéral le répète inlassablement depuis bientôt 30 ans. Néanmoins, les assurées ne baissent pas les bras et périodiquement resoumettent la question, espérant que de nouvelles données scientifiques sauront infléchir la Haute Cour. En vain. Le tribunal l'a redit en octobre 2012:1 cette prestation n'est pas à charge des caisses.2 L'ordonnance sur les prestations de l'assurance-maladie (OPAS3) le prévoit explicitement, et il n'y a simplement pas lieu d'examiner une disposition d'une ordonnance du Département fédéral de l'intérieur (DFI). Le raisonnement est toutefois un peu court. Premièrement, le refus du Tribunal fédéral d'examiner si l'ordonnance respecte le cadre de la délégation législative ne convainc pas. Deuxièmement, la FIV remplit les critères imposés à la prise en charge tels que décidés par le législateur dans la loi sur l'assurance-maladie (LAMal4). Enfin, les assurés qui décident de recourir contre un refus de remboursement sont privés des garanties minimales de procédure que leur garantit pourtant la Convention européenne des droits de l'homme. La présente contribution commence par une brève description de la FIV. Elle expose ensuite la législation applicable (partie 2) et la jurisprudence fédérale qui en découle (partie 3). La partie suivante critique la position du Tribunal fédéral au regard des principes énoncés dans la législation. Une comparaison avec l'insémination intra-utérine (IIU), pour laquelle le Tribunal fédéral a admis le remboursement, met en lumière les incohérences de la jurisprudence. La compatibilité de la jurisprudence fédérale avec l'art. 6 de la Convention européenne sur les droits de l'homme est évaluée. La conclusion plaide pour une réforme partielle du système procédural gouvernant la prise en charge des prestations de soins, mais aussi des techniques médicales alternatives.

Management of fragility fractures in Switzerland: results of a nationwide survey.

A nationwide survey was conducted in Switzerland to assess the quality level of osteoporosis management in patients aged 50 years or older presenting with a fragility fracture to the emergency ward of the participating hospitals. Eight centres recruited 4966 consecutive patients who presented with one or more fractures between 2004 and 2006. Of these, 3667 (2797 women, 73.8 years old and 870 men, 73.0 years old in average) were considered as having a fragility fracture and included in the survey. Included patients presented with a fracture of the upper limbs (30.7%), lower limbs (26.4%), axial skeleton (19.5%) or another localisation, including malleolar fractures (23.4%). Thirty-two percent reported one or more previous fractures during adulthood. Of the 2941 (80.2%) hospitalised women and men, only half returned home after discharge. During diagnostic workup, dual x-ray absorptiometry (DXA) measurement was performed in 31.4% of the patients only. Of those 46.0% had a T-score < or =-2.5 SD and 81.1% < or =-1.0 SD. Osteoporosis treatment rate increased from 26.3% before fracture to 46.9% after fracture in women and from 13.0% to 30.3% in men. However, only 24.0% of the women and 13.8% of the men were finally adequately treated with a bone active substance, generally an oral bisphosphonate, with or without calcium / vitamin D supplements. A positive history of previous fracture vs none increased the likelihood of getting treatment with a bone active substance (36.6 vs 17.9%, ? 18.7%, 95% CI 15.1 to 22.3, and 22.6 vs 9.9%, ? 12.7%, CI 7.3 to 18.5, in women and men, respectively). In Switzerland, osteoporosis remains underdiagnosed and undertreated in patients aged 50 years and older presenting with a fragility fracture.