Partículas de polietileno en líquido sinovial tras artroplastia de rodilla con un polietileno convencional o uno altamente entrecruzado. Estudio preliminar / Polyethylene particles in synovial fluid after knee arthroplasty with a conventional or highly cross-linked polyethylene. Preliminary study

Objetivo. En los últimos años han aparecido polietilenos altamente entrecruzados para intentar disminuir el desgaste, tal como se ha demostrado en simuladores de rodilla. El objetivo es evaluar mediante el recuento de partículas de polietileno en líquido sinovial, si se confirma un menor desgaste en pacientes con prótesis de polietileno altamente entrecruzado. Material y método. Estudio prospectivo aleatorizado, en el que durante la implantación de una prótesis de rodilla se asignó a un grupo de pacientes la colocación de un polietileno convencional (grupo A), y a otro grupo un polietileno altamente entrecruzado (X3® de Stryker Orthopaedics) (grupo B). A los 12 meses tras la cirugía se practicó una artrocentesis de rodilla y se hizo un recuento de partículas de polietileno en el líquido sinovial mediante microscopio electrónico de barrido. Se han analizado 14 muestras en cada grupo. Resultados. Ambos grupos son comparables en todas las variables estudiadas. No hemos hallado diferencias significativas en la concentración de partículas de polietileno/ml (1,49±0,85 millones grupo A vs. 1,42±0,91 millones grupo B; p=0,60) ni en el número total de partículas aisladas entre ambos grupos. Tampoco hemos hallado diferencias en el tamaño ni la morfología de partículas entre ambos grupos. Discusión y conclusiones. Aunque diversos trabajos in vitro han hallado una reducción muy significativa del desgaste del polietileno altamente entrecruzado, no se ha hallado que en las prótesis de rodilla implantadas en pacientes este desgaste se vea reducido. La gran variabilidad del número de partículas entre individuos sugiere que el desgaste de polietileno in vivo depende de muchos factores y probablemente el tipo de polietileno no sea el más determinante (AU)

Aim of the study. In recent years cross-linked polyethylenes have been developed in an attempt to reduce the wear, as has been demonstrated in knee simulators. The aim is to assess, by counting particles of polyethylene in synovial fluid, whether the reduction in wear is confirmed in patients with a highly crosslinked polyethylene prosthesis. Material and methods. A prospective randomised study was designed. During the implantation of a knee prosthesis, one group of patients was assigned the use of a conventional polyethylene (group A), and the other group a highly crosslinked polyethylene (X3®, Stryker Orthopaedics) (group B). At 12 months after surgery a knee arthrocentesis was performed, and the number of polyethylene particles was counted in a scanning electron microscopy. Fourteen samples from each group were studied. Results. Both groups were comparable in all study variables. We found no significant differences in the concentration of polyethylene particles/ml (1.49±0.85 million in group A vs 1.42±0.91 million in group B, P=.60) or the total number of isolated particles. We found no differences either in size or morphology of particles between both groups. Discussion and conclusions. Although several in vitro studies in vitro using different types of highly crosslinked polyethylene found a significant reduction, we did not find that that wear was reduced in the knees of these patients. The great variability in the number of particles between individuals suggests that polyethylene wear in vivo depends on many factors, so perhaps the type of polyethylene is not the most significant factor (AU)

[Polyethylene particles in synovial fluid after knee arthroplasty with a conventional or highly cross-linked polyethylene. Preliminary study]. / Partículas de polietileno en líquido sinovial tras artroplastia de rodilla con un polietileno convencional o uno altamente entrecruzado. Estudio preliminar.

AIM OF THE STUDY: In recent years cross-linked polyethylenes have been developed in an attempt to reduce the wear, as has been demonstrated in knee simulators. The aim is to assess, by counting particles of polyethylene in synovial fluid, whether the reduction in wear is confirmed in patients with a highly crosslinked polyethylene prosthesis. MATERIAL AND METHODS: A prospective randomised study was designed. During the implantation of a knee prosthesis, one group of patients was assigned the use of a conventional polyethylene (group A), and the other group a highly crosslinked polyethylene (X3, Stryker Orthopaedics) (group B). At 12 months after surgery a knee arthrocentesis was performed, and the number of polyethylene particles was counted in a scanning electron microscopy. Fourteen samples from each group were studied. RESULTS: Both groups were comparable in all study variables. We found no significant differences in the concentration of polyethylene particles/ml (1.49 ± 0.85 million in group A vs 1.42 ± 0.91 million in group B, P=.60) or the total number of isolated particles. We found no differences either in size or morphology of particles between both groups. DISCUSSION AND CONCLUSIONS: Although several in vitro studies in vitro using different types of highly crosslinked polyethylene found a significant reduction, we did not find that that wear was reduced in the knees of these patients. The great variability in the number of particles between individuals suggests that polyethylene wear in vivo depends on many factors, so perhaps the type of polyethylene is not the most significant factor.

[Does patient's gender affect the quality of clinical histories in primary care?]. / Influye el género del paciente en la calidad de las historias clínicas de atención primaria?

OBJECTIVE: The objective of this study was to analyse and quantify the effect of patients gender on Primary Care clinical histories (PCCH) of the over-14 population. DESIGN: An observational cross-sectional study. SETTING: Primary Health Care. PATIENTS AND OTHER PARTICIPANTS: A total sample of 1,449 PCCH from six Health Districts in Catalonia were evaluated. These districts had a professional staff of 55 doctors, 55 nurses and 30 clerical auxiliaries. MEASUREMENTS AND MAIN RESULTS: Internal audit of the random sample of 1,449 PCCH was carried out to see that they satisfied the following criteria: PCCH belonging to population registered in the District, born before 1980 and who had attended for consultation at least once in the previous five years (between 1990 and 1994). To measure the quality of PCCHs, a questionnaire with 23 structured indicators in three sections was used to collect information on recording of sociodemographic data, administrative details and data concerning health. Higher recording of all items occurred in female users, older users, less time elapsed since previous consultation, and when the town where the PC Centre was located had < 1000 inhabitants. CONCLUSIONS: The analysis of the results suggests the need to improve the effectiveness of the PCCH as an instrument to achieve equality in individual care.

The flying cylinder: a new algorithm for filament recognition in noisy stereo images.

We present a new method of automatic 3D filament representation which uses stereo micrographs to reconstruct three-dimensional trajectories of filament-like objects as DNA molecules. The method deals with low contrasted and noisy images, as obtained from cryovitrified samples by means of electron microscopy. The three-dimensional information is extracted from skeletizing simultaneously both images of a given stereo-pair, instead of processing them separately. The main advantages of the technique are reproducibility and speed, compared to the reconstruction done by manual registration, i.e., clicking on the stereo micrographs.