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Introducción La luxación expuesta de rodilla es compleja, de incidencia baja con grandes secuelas funcionales. Existen escasos reportes de series en la literatura relativos a su manejo y resultados. Objetivo El objetivo de este trabajo fue describir los resultados obtenidos de todos los pacientes con luxación expuesta de rodilla tratados durante las últimas dos décadas en nuestro hospital bajo un mismo estándar de tratamiento. Método Estudio descriptivo retrospectivo en una serie quirúrgica de 11 pacientes con luxación expuesta de rodilla, tratados entre 1994 y 2015. Todos fueron estudiados y manejados según esquema estandarizado: Angiografía/ angioTC, aseo quirúrgico, fijador externo y reparación neurovascular en casos necesarios. Revisión de registros clínicos e imagenológicos consignando datos demográficos, lesiones concomitantes, número y tipo de cirugías, y complicaciones asociadas. Seguimiento promedio fue de 10,7 años con evaluación mediante encuesta funcionales SF-12/IKDC durante el mes de marzo de 2015. Resultados Diez pacientes eran hombres, 1 mujeres. Edad promedio al accidente 38,6 años. Mecanismo lesional de alta energía; como referencia la clasificación de Schenck, 1 lesión III-M, 4 tipo IV y los 6 restantes una tipo V. 4 lesiones vasculares (36.4%) y 7 lesiones neurológicas (63.6%). Tratamiento definitivo consistió en 4 reconstrucciones ligamentarias, 2 prótesis, 3 artrodesis y 2 amputaciones supracondíleas. Evaluaciones funcionales dieron como resultados un puntaje promedio de 37 y 48,5 para SF-12 físico y mental respectivamente, y de 44,1 para IKDC. Conclusión La luxación expuesta de rodilla es una lesión infrecuente, muy compleja, asociada a accidentes de alta energía, con complicaciones severas, lo que determina resultados funcionales relativamente malos. La estandarización permite sistematizar las distintas etapas de atención, racionalizar los recursos disponibles evitando la improvisación en momentos críticos, lo que podría incidir en la obtención de resultados.Nivel de Evidencia IV Serie de casos.

Abstract. Masaya (Nicaragua, 12.0∘ N, 86.2∘ W; 635 m a.s.l.) is one of the few volcanoes hosting a lava lake, today. This study has two foci: (1) discussing the state of the art of long-term SO2 emission flux monitoring with the example of Masaya and (2) the provision and discussion of a continuous data set on volcanic gas data with a large temporal coverage, which is a major extension of the empirical database for studies in volcanology as well as atmospheric bromine chemistry. We present time series of SO2 emission fluxes and BrO/SO2 molar ratios in the gas plume of Masaya from March 2014 to March 2020 – covering the three time periods (1) before the lava lake appearance, (2) a period of high lava lake activity (November 2015 to May 2018), and (3) after the period of high lava lake activity. For these three time periods, we report average SO2 emission fluxes of (1000±200), (1000±300), and (700±200) t d−1 and average BrO/SO2 molar ratios of (2.9±1.5)×10-5, (4.8±1.9)×10-5, and (5.5±2.6)×10-5. Our SO2 emission flux retrieval is based on a comprehensive investigation of various aspects of spectroscopic retrievals, the wind conditions, and the plume height. We observed a correlation between the SO2 emission fluxes and the wind speed in the raw data. We present a partial correction of this artefact by applying dynamic estimates for the plume height as a function of the wind speed. Our retrieved SO2 emission fluxes are on average a factor of 1.4 larger than former estimates based on the same data. Further, we observed different patterns in the BrO/SO2 time series: (1) an annual cyclicity with amplitudes between 1.4 and 2.5×10-5 and a weak semi-annual modulation, (2) a step increase by 0.7×10-5 in late 2015, (3) a linear trend of 1.4×10-5 per year from November 2015 to March 2018, and (4) a linear trend of -0.8×10-5 per year from June 2018 to March 2020. The step increase in 2015 coincided with the lava lake appearance and was thus most likely caused by a change in the magmatic system. We suggest that the cyclicity might be a manifestation of meteorological cycles. We found an anti-correlation between the BrO/SO2 molar ratios and the atmospheric water concentration (correlation coefficient of −0.47) but, in contrast to that, neither a correlation with the ozone mixing ratio (+0.21) nor systematic dependencies between the BrO/SO2 molar ratios and the atmospheric plume age for an age range of 2–20 min after the release from the volcanic edifice. The two latter observations indicate an early stop of the autocatalytic transformation of bromide Br− solved in aerosol particles to atmospheric BrO.

Abstract. Masaya volcano (Nicaragua, 12.0° N, 86.2° W, 635 m a.s.l.) is one of the few volcanoes hosting a lava lake, today. We present continuous time series of SO2 emission fluxes and BrO / SO2 molar ratios in the gas plume of Masaya from March 2014 to March 2020. This study has two foci: (1) discussing the state of the art of long-term SO2 emission flux monitoring on the example of Masaya and (2) the provision and discussion of a continuous dataset on volcanic gas data unique in its temporal coverage, which poses a major extension of the empirical data base for studies on the volcanologic as well as atmospheric bromine chemistry. Our SO2 emission flux retrieval is based on a comprehensive investigation of various aspects of the spectroscopic retrievals, the wind conditions, and the plume height. Our retrieved SO2 emission fluxes are on average a factor of 1.4 larger than former estimates based on the same data. We furthermore observed a correlation between the SO2 emission fluxes and the wind speed when several of our retrieval extensions are not applied. We make plausible that such a correlation is not expected and present a partial correction of this artefact via applying dynamic estimates for the plume height as a function of the wind speed (resulting in a vanishing correlation for wind speeds larger than 10 m/s). Our empirical data set covers the three time periods (1) before the lava lake elevation, (2) period of high lava lake activity (December 2015–May 2018), (3) after the period of high lava lake activity. For these three time periods, we report average SO2 emission fluxes of 1000 ± 200 t d−1, 1000 ± 300 t d−1, and 700 ± 200 t d−1 and average BrO / SO2 molar ratios of (2.9 ± 1.5) × 10−5, (4.8 ± 1 : 9) ×10−5, and (5.5 ± 2–6) × 10−5. These variations indicate that the two gas proxies provide complementary information: the BrO / SO2 molar ratios were susceptible in particular for the transition between the two former periods while the SO2 emission fluxes were in particular susceptible for the transition between the two latter time periods. We observed an extremely significant annual cyclicity for the BrO / SO2 molar ratios (amplitudes between 1–4–2–6 × 10−5) with a weak semi-annual modulation. We suggest that this cyclicity might be a manifestation of meteorological cycles. We found an anti-correlation between the BrO / SO2 molar ratios and the atmospheric water concentration (correlation coefficient of −47 %) but in contrast to that neither a correlation with the ozone mixing ratio (+21 %) nor systematic dependencies between the BrO / SO2 molar ratios and the atmospheric plume age for an age range of 2–20 min after the release from the volcanic edifice. The two latter observations indicate an early stop of the autocatalytic partial transformation of bromide Br− solved in aerosol particles to atmospheric BrO. Further patterns in the BrO / SO2 time series were (1) a step increase by 0.7 × 10−5 in late 2015, (2) a linear trend of 1.2 × 10−5 per year from December 2015 to March 2018, and (3) a linear trend of −0.8 × 10−5 per year from June 2018 to March 2020. The step increase in 2015 coincided with the 55 elevation of the lava lake and was thus most likely caused by a change in the magmatic system. The linear trend between late 2015 and early 2018 may indicate the evolution of the magmatic gas phase during the ascent of juvenile gas-rich magma whereas the linear trend from June 2018 on may indicate a decreasing bromine abundance in the magma.

Monitoring the state of active volcanoes is the foundational component of volcanic risk reduction strategies. To a large extent, these responsibilities rest with volcano observatories. Based on the 11 Reports that constitute this Special Issue—“Volcano Observatories in Latin America”—we provide a comprehensive overview of the work that has been carried out by the observatories in Latin America, a region in which tens of millions of people are exposed to volcanic activity. Since the first steps taken in the 1980s, volcano observatories of the region have made significant progress in assessing and monitoring volcanic activity. Currently, 17 institutions officially contribute to monitoring 135 volcanoes in 10 countries. Along with the improvements in the instrumental, technical, and operational capabilities, advancements have been made in long-term hazard assessment and hazard communication. But despite all the progress accomplished, several challenges and limiting factors still remain, such as the lack of financial resources and training opportunities. Efforts should be focused on increasing the number and quality of monitoring networks. El monitoreo del estado de los volcanes activos es un componente fundamental de las estrategias para la reducción del riesgo volcánico. En gran medida, estas responsabilidades recaen en los observatorios volcánicos. A partir de los 11 Reportes que constituyen este Número Especial –“Observatorios volcanológicos en América Latina”– brindamos un detallado resumen del trabajo llevado adelante por los observatorios en Latinoamérica, una región con decenas de millones de personas expuestas a la actividad volcánica. Desde sus primeros pasos a principios de 1980, los observatorios volcanológicos de la región han logrado avances significativos en la evaluación y vigilancia de la actividad volcánica. Actualmente, 17 instituciones contribuyen oficialmente al monitoreo de 135 volcanes en 10 países. Junto con las mejoras en sus capacidades instrumentales, técnicas y operativas, se produjeron avances también en la evaluación y comunicación de peligros a largo plazo. A pesar del avance logrado, aún persisten desafíos y factores limitantes, como la falta de recursos económicos y oportunidades de capacitación. Los esfuerzos futuros deben centrarse en aumentar el número y la calidad de las redes de monitoreo.