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Reparaci贸n de defectos segmentales 贸seos con vidrio bioactivo y una membrana no absorbible
The authors inform the repair of segmental bone defects of critical size with the use of a combination of bioactive glass and a non-absorbable membrane of expanded politetrafluoroethilen (ePTF). Twenty four New Zealand rabbits - sexually mature males and females - were used. They were kept in individual cages with controlled temperature and fed ad libitum with a commercial formula. A critical segmental defect in the diaphysis of the radius was created in each rabbit. The defect was filled with bioactive glass granules with a particle size of 300 to 600 um . The extremes of the radius and the granules of bioactive glass were wrapped up with a ePTF membrane. Immediately after the surgical procedure, and every 30 days during a period of 150 days, X-ray controls of the operated limbs were carried out. The rabbits recovered total bearing between 48 - 72 hs. after the operation. After 150 days of treatment, the defects were repaired in all the rabbits. The control X-rays taken after the operation showed that the partic1es of glass occupied the defect had a thin granular shape. Thirty days later, the granules were not differentiated and made up a uniform and radio-dense mass that became more radio-dense in the following radiographic controls. After 150 days the x-ray images showed that the defects were fully repaired. At that moment, the animals were killed to make a macro- and microscopic analysis of the newly-formed bone. The sagittal cuts of the histological tissue that inc1uded the ends of the radius and the newly-formed bone showed that the segmental bone was constituted by numerous trabeculas that contained bone marrow and isolated presence of glass granules. The ePTF membrane protected the bioactive glass granules mixed with the blood clot coming from the cut bone tips. The ionic exchanges between the ions of Ca and P of the glass granules and the same ions of the tissue were evident 30 days after the operation when they fused. Since then, the processes of osteoconduction and osteoinduction started. The scarce presence of granules contained in the newly-formed bone suggest that the granules were absorbed. The bone regeneration was possible due to the protective action of the blood clot of the ePTF membrane and to the osteoinductive action of the bioactive glass granules that unfettered the mechanism of proliferation of the mesenchymal cells and their differentiation into osteoblasts and marrow tissue. The combination ofboth bio-materials fosters the induction ofbone tissue in long bonesSe informa la reparaci贸n de defectos segmentales 贸seos de tama帽o cr铆tico mediante la combinaci贸n de vidrio bioactivo y una membrana no absorbible de politetrafluoroetileno expandido (PTFe). Se emplearon 24 conejos neocelandeses machos y hembras sexualmente maduros a los que se les cre贸 un defecto segmental cr铆tico en las di谩fisis de los radios. El defecto se rellen贸 con part铆culas de vidrio bioactivo. Los cabos del radio y los gr谩nulos se envolvieron con una membrana de PTFe. Inmediatamente de finalizadas las intervenciones, cada 30 d铆as y durante 150 d铆as se efectuaron controles radiol贸gicos de los miembros intervenidos. Transcurridos los 150 d铆as de tratamiento en la totalidad de los ensayos se observ贸 que los defectos se hallaban reparados. Las radiografias de control tomadas luego de finalizadas las operaciones mostraban a las part铆culas de vidrio ocupando el defecto a modo de un fino granulado; a los 30 d铆as los gr谩nulos no se distingu铆an entre s铆 y conformaban una masa uniforme y radiodensa que con el transcurso de los controles adquiri贸 mayor radiodensidad; a los 150 d铆as la imagen era la reparaci贸n de los defectos. A los 150 d铆as los animales fueron sacrificados para efectuar an谩lisis macro y microsc贸pico del hueso neoformado. Los estudios histol贸gicos efectuados en cortes sagitales que incluyeron los extremos del radio y el hueso neoformado que el hueso regenerado estaba constituido por numerosas trab茅culas que conten铆an m茅dula roja y presencia aislada de gr谩nulos de vidrio. La membrana de PTFe protegi贸 los gr谩nulos de vidrio bioactivo mezclado con el co谩gulo de sangre proveniente de los cabos 贸seos seccionados. Las reacciones qu铆micas de los gr谩nulos con los l铆quidos tisulares se pusieron en evidencia a los 30 d铆as cuando 茅stos se fusionaron, momento a partir del cual comenz贸 los procesos de osteoconducci贸n y osteoinducci贸n. Los mecanismos de proliferaci贸n y diferenciaci贸n mesenquim谩tica que promueven y desencadenan la combinaci贸n del PTFe y los gr谩nulos de vidrio bioactivo permitieron la reparaci贸n del defecto con la generaci贸n de hueso nuevo conteniendo m茅dula roja. La combinaci贸n de los biomateriales promueven la inducci贸n de tejido 贸seo en huesos largo