Two extensions of consumer surplus

We study consumer surplus in a single market when (a) there is a lower bound in the consumption of the outside good and (b) the weights in the social welfare function given to consumers and firms are different. We assume quasilinear utility. When the lower bound constraint on the consumption of the outside good is binding, income effects arise in demand. In some cases, Cournot equilibrium output is below equilibrium output without this constraint because the constraint makes demand less elastic.When the weights given to consumers and firms are not identical, social welfare is not necessarily concave and profits might be negative at the unrestricted optimum. We characterize social welfare optimum with a bound on maximum losses in a class of utility functions. We offer a formula to find the percentage of welfare losses due to oligopoly in this case

Rotura de vástago femoral de prótesis total de cadera enteramente recubierta de hidroxiapatita. Presentación de tres casos.

Presentamos la descripción de tres casos de rotura de vástago femoral de una prótesis total de cadera enteramente recubierta de hidroxiapatita (Furlong, JRI limited, London), sin antecedente traumático. En dos pacientes el tiempo de evolución fue de 7 años tras el implante primario, y en un caso la rotura del vástago se produjo a los 5 años. El fallo del implante se produjo en todos los casos a nivel de la zona de transición metafiso-diafisaria- infundibulo-. La osteointegración del implante en la porción distal del vástago, favorecida por el recubrimiento de hidroxiapatita produce una transmisión anómala de cargas a nivel de la unión metafisodiafisaria y aumenta el riesgo de fallo del material en los casos descritos.We are describing 3 cases of femoral component failure of a total hip arthroplasty with fully coated hidroxiapa- tite (Furlong, JRI limited, London), without any traumatic event. The follow-up before failure was 7 and 5 years. The fracture of femoral stem was always just distal to the metap- hisal cone. The ingrowth of the distal portion of the femoral component increased by hidrixiapatite causes abnormal transmission of biomechanical forces in the metafiso-diafisal union increasing the risk of material failure

Manejo de la infección protésica de hombro con gran defecto óseo: descripción de un caso complejo

La infección periprotésica de hombro tiene una incidencia de entre el 0.4% al 2.9%; su tratamiento es controvertido y se basa en la experiencia sobre infecciones protésicas de rodilla y cadera. Presentamos el caso de una paciente quien fue tratada mediante recambio en dos tiempos, la cual presentó como complicación añadida un gran defecto óseo metafisodiafisario tratado siguiendo pautas establecidas en la literatura actual, con buen resultado final, valorando aspectos analíticos, radiológicos y clínicosShoulder periprosthetic infection has an incidence of 0.4% to 2.9%; treatment is controversial and is based on the experience of prosthetic hip and knee infections. We report a patient who was treated by two-stage exchange, which added complication presented as a large bone defect treated following guidelines established in the current literature, with good outcome, evaluating blood analysis, radiological and clinical aspects

Normal response to tibial neurodynamic test in asymptomatic subjects

BACKGROUND: The straight leg raise test (SLR) is one of the most performed physical tests for mechanosensitivity and impairment of the nervous system. According to the anatomy of the tibial nerve, ankle dorsiflexion and eversion movements could be used to perform the tibial neurodynamic test (TNT). To date, no study has documented the normal responses of the TNT. OBJECTIVE: To document normal responses of the TNT in asymptomatic individuals and to investigate influences from sex and leg dominance. METHODS: A cross-sectional study with 44 asymptomatic volunteer subjects, a total of 88 lower limbs, was carried out. The range of motion (ROM), quality, and distribution of sensory responses were recorded. The hip flexion ROM was measured when subjects reported an intensity of their symptoms of 2/10 (P1) and 8/10 (P2). RESULTS: The mean ROM for hip flexion at P1 was 44.22 ± 13.13 and 66.73 ± 14.30 at P2. Hip flexion was significantly greater at P2 than P1 (p 0.05). The descriptor of the quality of sensory responses most often used by participants was stretching (88.6% and 87.5% for P1 and P2, respectively) in the popliteal fossa and posterior calf. CONCLUSIONS: This study describes the sensory responses of asymptomatic subjects resulting from the TNT. Our findings indicate that TNT responses are independent of the influence of sex or leg dominance

Tratamiento de fracturas de húmero proximal en hueso osteoporótico mediante fijación con sistema de aumentación

Introducción. Para el tratamiento de fracturas de húmero proximal en pacientes osteoporóticos, se han desarrollado fijaciones con aumentación que mejoran la estabilidad del implante. El objetivo de este estudio es analizar los resultados obtenidos con la técnica empleada. Material y métodos. Estudio descriptivo retrospectivo de 7 pacientes con fracturas en 3-4 fragmentos intervenidos mediante placa Philos (Synthes)® de aumentación. Seguimiento medio de 12 meses. Resultados. La puntuación media en la Escala Visual Analógica de dolor fue de 4,4. En la escala Quick Dash de 47,47. En la Escala Constant-Murley de 36,36. La abducción activa media fue de 95º; la flexión anterior media de 105º; la rotación externa media de 44,14º; la rotación interna alcanzó en tres pacientes S1, en dos L5, en uno L2 y en otro T10. En los controles radiográficos se mantuvo la reducción. Nos encontramos con un caso de consolidación parcial. Conclusión. Las técnicas de aumentación disminuyen el riesgo de fallos de fijación manteniendo la reducción.. Introduction. To treat proximal humerus fractures in patients with osteoporosis, the last few years, systems to improve implant stability by augmentation techniques have been developed. The aim of this study is to analyze the results obtained with the surgical technique employed. Materials and methods. Retrospective descriptive study. We selected 7 patients with 3 or 4- part fractures treated operatively with Philos Augmentation plate (Synthes)® fixation technique. Average follow-up was 12 months. Results. Pain measured with a Visual Analogical Scale (VAS) got a average value of 4,4. The mean Quick Dash Score was 47,47. The mean Constat-Murley modified was 36,36. The active articular balances showed a mean abduction of 91º; mean anterior flexion of 105º; mean external rotation of 44,14º; and finally the internal rotation achieved in three patients got to S1, in two patients to L5, in one patient to L2 and in other patient to T10. In X- Ray post-operative controls we can appreciate the reduction maintenance. In one case we observe a partial consolidation of the fracture. Conclusion. Surgical techniques that imply implant augmentation reduces the risk of implant failure and maintains the fracture reduction