Evolución de los niveles séricos de cromo y cobalto tras el empleo de un vástago con cuello modular en la artroplastia total de cadera primaria / Evolution of chromium and cobalt serum levels after the use of a modular neck stem in primary total hip arthroplasty

Introducción y objetivos: Los vástagos primarios con cuellos modulares fueron introducidos con la ventaja teórica de restaurar la anatomía de la cadera de forma más precisa. Sin embargo, la presencia de un segundo encaje se ha asociado a una mayor corrosión y liberación de detritos metálicos. El objetivo de nuestro estudio es cuantificar los valores séricos de cromo y de cobalto, y analizar su evolución temporal durante cinco años. Material y métodos: Se presenta una serie prospectiva de 61 pacientes intervenidos de artroplastia total de cadera primaria mediante la implantación del vástago HMAX-M® (Limacorporate, San Daniele, Italia) en los que se realizó una determinación sérica de cromo y cobalto a los seis meses, a los dos años y a los cinco años. Resultados: Nuestra serie presenta una elevación progresiva de los niveles de cromo, con una diferencia significativa entre los valores de cromo a los seis meses (0,35±0,18) y los cinco años (0,52±0,36), p=0,01. Respecto al cobalto, se observa una elevación estadísticamente significativa entre los seis meses y los dos años y una posterior estabilización hasta los cinco años, siendo la media de cobalto a los seis meses (1,17±0,8) significativamente menor que a los dos años (2,63±1,76) y a los cinco años (2,84±2,1), p=0,001. Conclusión: Se ha observado una elevación de los niveles séricos de cobalto en aquellos pacientes a los que se les implantó un vástago con cuello modular. Los resultados obtenidos en este estudio han limitado el uso de vástagos con cuello modular en nuestra práctica habitual.(AU)

Introduction and objectives: Modular neck primary stems were introduced with the theoretical advantage of restoring the hip anatomy more precisely. However, the presence of a second junction has been associated with increased corrosion and release of metal debris. The objective of our study is to quantify of chromium and cobalt serum values, and to analyze their temporal evolution during five years. Material and methods: We present a prospective series of 61 patients who underwent primary total hip arthroplasty by implantation of the HMAX-M® stem (Limacorporate, San Daniele, Italy). Serum chromium and cobalt determinations were performed at six months, two years and five years. Results: Our series shows a progressive elevation in chromium levels with a significant difference between chromium values at six months (0.35±0.18) and five years (0.52±0.36), P=.01. Regarding cobalt, a statistically significant elevation is observed between six months and two years and a subsequent stabilization of values between two and five years, with a cobalt mean at six months (1.17±0.8) significantly lower than at two (2.63±1.76) and five years (2.84±2.1), P=.001. Conclusion: Elevated serum cobalt levels have been observed in patients who underwent modular neck stem implantation. The results obtained in this study have limited the use of stems with a modular neck in our clinical practice.(AU)

[Translated article] Evolution of chromium and cobalt serum levels after the use of a modular neck stem in primary total hip arthroplasty / Evolución de los niveles séricos de cromo y cobalto tras el empleo de un vástago con cuello modular en la artroplastia total de cadera primaria

Introducción y objetivos: Los vástagos primarios con cuellos modulares fueron introducidos con la ventaja teórica de restaurar la anatomía de la cadera de forma más precisa. Sin embargo, la presencia de un segundo encaje se ha asociado a una mayor corrosión y liberación de detritos metálicos. El objetivo de nuestro estudio es cuantificar los valores séricos de cromo y de cobalto, y analizar su evolución temporal durante cinco años. Material y métodos: Se presenta una serie prospectiva de 61 pacientes intervenidos de artroplastia total de cadera primaria mediante la implantación del vástago HMAX-M® (Limacorporate, San Daniele, Italia) en los que se realizó una determinación sérica de cromo y cobalto a los seis meses, a los dos años y a los cinco años. Resultados: Nuestra serie presenta una elevación progresiva de los niveles de cromo, con una diferencia significativa entre los valores de cromo a los seis meses (0,35±0,18) y los cinco años (0,52±0,36), p=0,01. Respecto al cobalto, se observa una elevación estadísticamente significativa entre los seis meses y los dos años y una posterior estabilización hasta los cinco años, siendo la media de cobalto a los seis meses (1,17±0,8) significativamente menor que a los dos años (2,63±1,76) y a los cinco años (2,84±2,1), p=0,001. Conclusión: Se ha observado una elevación de los niveles séricos de cobalto en aquellos pacientes a los que se les implantó un vástago con cuello modular. Los resultados obtenidos en este estudio han limitado el uso de vástagos con cuello modular en nuestra práctica habitual.(AU)

Introduction and objectives: Modular neck primary stems were introduced with the theoretical advantage of restoring the hip anatomy more precisely. However, the presence of a second junction has been associated with increased corrosion and release of metal debris. The objective of our study is to quantify of chromium and cobalt serum values, and to analyze their temporal evolution during five years. Material and methods: We present a prospective series of 61 patients who underwent primary total hip arthroplasty by implantation of the HMAX-M® stem (Limacorporate, San Daniele, Italy). Serum chromium and cobalt determinations were performed at six months, two years and five years. Results: Our series shows a progressive elevation in chromium levels with a significant difference between chromium values at six months (0.35±0.18) and five years (0.52±0.36), P=.01. Regarding cobalt, a statistically significant elevation is observed between six months and two years and a subsequent stabilization of values between two and five years, with a cobalt mean at six months (1.17±0.8) significantly lower than at two (2.63±1.76) and five years (2.84±2.1), P=.001. Conclusion: Elevated serum cobalt levels have been observed in patients who underwent modular neck stem implantation. The results obtained in this study have limited the use of stems with a modular neck in our clinical practice.(AU)

Evolution of chromium and cobalt serum levels after the use of a modular neck stem in primary total hip arthroplasty. / Evolución de los niveles séricos de cromo y cobalto tras el empleo de un vástago con cuello modular en la artroplastia total de cadera primaria.

INTRODUCTION AND OBJECTIVES: Modular neck primary stems were introduced with the theoretical advantage of restoring the hip anatomy more precisely. However, the presence of a second junction has been associated with increased corrosion and release of metal debris. The objective of our study is to quantify of chromium and cobalt serum values, and to analyze their temporal evolution during five years. MATERIAL AND METHODS: We present a prospective series of 61 patients who underwent primary total hip arthroplasty by implantation of the HMAX-M® stem (Limacorporate, San Daniele, Italy). Serum chromium and cobalt determinations were performed at six months, two years and five years. RESULTS: Our series shows a progressive elevation in chromium levels with a significant difference between chromium values at six months (0.35±0.18) and five years (0.52±0.36), P=.01. Regarding cobalt, a statistically significant elevation is observed between six months and two years and a subsequent stabilization of values between two and five years, with a cobalt mean at six months (1.17±0.8) significantly lower than at two (2.63±1.76) and five years (2.84±2.1), P=.001. CONCLUSION: Elevated serum cobalt levels have been observed in patients who underwent modular neck stem implantation. The results obtained in this study have limited the use of stems with a modular neck in our clinical practice.

[Translated article] Evolution of chromium and cobalt serum levels after the use of a modular neck stem in primary total hip arthroplasty.

INTRODUCTION AND OBJECTIVES: Modular neck primary stems were introduced with the theoretical advantage of restoring the hip anatomy more precisely. However, the presence of a second junction has been associated with increased corrosion and release of metal debris. The objective of our study is to quantify of chromium and cobalt serum values, and to analyse their temporal evolution during five years. MATERIAL AND METHODS: We present a prospective series of 61 patients who underwent primary total hip arthroplasty by implantation of the H MAX-M® stem (Limacorporate, San Daniele, Italy). Serum chromium and cobalt determinations were performed at six months, two years and five years. RESULTS: Our series shows a progressive elevation in chromium levels with a significant difference between chromium values at six months (0.35±0.18) and five years (0.52±0.36), p=.01. Regarding cobalt, a statistically significant elevation is observed between six months and two years and a subsequent stabilisation of values between two and five years, with a cobalt mean at six months (1.17±0.8) significantly lower than at two (2.63±1.76) and five years (2.84±2.1), p=.001. CONCLUSION: Elevated serum cobalt levels have been observed in patients who underwent modular neck stem implantation. The results obtained in this study have limited the use of stems with a modular neck in our clinical practice.

Preservación ósea femoral con tallos cortos de fijación cervicometafisaria. Estudio radiográfico comparativo con tallos no cementados de fijación metafisaria / Femoral bone presevation using short stems with metaphyseal fixation

Introducción: Los tallos no cementados recubiertos con hidroxiapatita de fijación metafisaria han logrado excelentes resultados a largo plazo. La segunda generación de tallos cortos de fijación cervicometafisaria ha surgido a principios de la década de 1990, con el objetivo de preservar capital óseo femoral. Sin embargo, la preservación ósea femoral teóricamente propuesta no ha sido comprobada. El objetivo de este trabajo es determinar radiográficamente la preservación del capital óseo femoral cuando se utilizó un tallo corto de fijación cervicometafisaria, comparando las radiografías posoperatorias con la programación del tallo que se debería haber utilizado en caso de ser un diseño convencional con fijación metafisaria. Materiales y Métodos: Los primeros 50 tallos cortos de fijación cervicometafisaria (MiniHip TM, Corin, Cirencester, Reino Unido) fueron analizados por dos observadores independientes, con radiografías de frente, en cuanto a nivel de resección cervical y longitud del tallo, comparándolos con las filminas de un tallo convencional de fijación metafisodiafisaria (MetaFix TM, Corin, Cirencester, Reino Unido). Resultados: Según el análisis radiográfico, los tallos cortos de fijación cervicometafisaria ocuparon una longitud femoral promedio de 79 mm (rango 68-102). Los tallos convencionales de fijación metafisaria hubiesen ocupado, en promedio, 73 mm más que los tallos cortos (rango 47-94). Esta distribución se observó en el corte de cuello (promedio 10 mm más distal) y en la longitud del implante (promedio 66 mm mayor longitud) (p <0,001). Esta diferencia permite preservar un 42% el capital óseo femoral. Conclusión: La preservación ósea relacionada con el uso de tallos cortos de fijación cervicometafisaria podría traer beneficios a largo plazo en pacientes jóvenes con alta demanda funcional.

Background: 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 (MiniHip TM, 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 (MetaFix TM, 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 <0.001). Conclusion: Femoral bone preservation may be related to long-term benefits especially in young patients.