Preservación ósea femoral con tallos cortos de fijación cervicometafisaria

espanolIntroduccion: los tallos no cementados recubiertos con hidroxiapatita de fijacion metafisaria han logrado excelentes resultados a largo plazo. La segunda generacion de tallos cortos de fijacion cervicometafisaria ha surgido a principios de la decada de 1990, con el objetivo de preservar capital oseo femoral. Sin embargo, la preservacion osea femoral teoricamente propuesta no ha sido comprobada. El objetivo de este trabajo es determinar radiograficamente la preservacion del capital oseo femoral cuando se utilizo un tallo corto de fijacion cervicometafisaria, comparando las radiografias posoperatorias con la programacion del tallo que se deberia haber utilizado en caso de ser un diseno convencional con fijacion metafisaria.Materiales y Metodos: los primeros 50 tallos cortos de fijacion cervicometafisaria (MiniHipTM, Corin, Cirencester, Reino Unido) fueron analizados por dos observadores independientes, con radiografias de frente, en cuanto a nivel de reseccion cervical y longitud del tallo, comparandolos con las filminas de un tallo convencional de fijacion metafisodiafisaria (MetaFixTM, Corin, Cirencester, Reino Unido).Resultados: segun el analisis radiografico, los tallos cortos de fijacion cervicometafisaria ocuparon una longitud femoral promedio de 79 mm (rango 68-102). Los tallos convencionales de fijacion metafisaria hubiesen ocupado, en promedio, 73 mm mas que los tallos cortos (rango 47-94). Esta distribucion se observo en el corte de cuello (promedio 10 mm mas distal) y en la longitud del implante (promedio 66 mm mayor longitud) (p EnglishBackground: uncemented hydroxyapatite-coated stems with methaphyseal fixation have demonstrated excellent long-term results. Second generation of short stems has been developed in the 90’s with the purpose to preserve femoral bone at the femoral neck and diaphysis. However, the amount of bone that would be theoretically saved has not been well-established. To radiographically determine femoral bone preservation in a series of patients operated on with a short, neck preserving stem, we compared these results with the length of a templated conventional length, uncemented hydroxyapatite-coated stem.Methods: the first 50 short hydroxyapatite-coated uncemented stems (MiniHipTM, Corin, Cirencester, UK) were radiographically analyzed by two independent observers measuring the level of neck cut and the stem length. Then, these results were compared with the level of neck cut and stem length when a conventional, metaphysodiaphyseal stem (MetaFixTM, Corin, Cirencester, UK) was implanted using templates.Results: according to the radiographic results, short stems measured an average length of 79 mm (range 68-102). Conventional stems would have required 78 mm (range 47-94) more bone for fixation than short stems. This difference was observed in the neck cut (average 10 mm more distal with a conventional stems), as well as in the diaphysis (average 66 mm more distal with a conventional stems) (p