Analysis of the Risk of Wear on Cemented and Uncemented Polyethylene Liners According to Different Variables in Hip Arthroplasty

Abstract

Las partíclas de desgaste en la artroplastia total de cadera (ATC) es una de las principales causas de fallo. La óptima fijación acetabular en la ATC primaria es todavía motivo de controversia porque no existe diferecnia significativa entre la cementada y la no cementada para largo plazo y resultados funcionales. Para evaluar y predecir, desde un punto de vista teórico, el riesgo de desgaste con dos tipos de liners de polietileno, cementado y no cementado, se ha llevado a cabo un estudio de simulación por elementos finitos del riesgo de desgaste. Las variables empleadas para la evaluación del riesgo de desgaste fueron: colocación del liner respecto del centro de rotación, espesor del liner, material de la cabeza femoral y la repación cervico-diafisiaria de la parte proximal del femur. En las 72 simmulaciones realizadas se observó un mejor comportamiento de las solución cementada respecto al riesgo de desgaste. Con respecto a las otars variables se observo una significación estadística. El mayor valor de riesgo de desgaste se observó en los liner con 5,3 mm de espesor y en posiciin superolateral de 25 mm respecto al centro de rotación. Según nuestros resultados, de cara a la recosntrucción acetabular, debe emplearse liner por encima de 5 mm de espesor en fijación cementada.Wear debris in total hip arthroplasty is one of the main causes of loosening and failure, and the optimal acetabular fixation for primary total hip arthroplasty is still controversial because there is no significant difference between cemented and uncemented types for long-term clinical and functional outcome. To assess and predict, from a theoretical viewpoint, the risk of wear with two types of polyethylene liners, cemented and uncemented, a simulation using the finite element (FE) method was carried out. The risk of wear was analyzed according to different variables: the polyethylene acetabular component’s position with respect to the center of rotation of the hip; the thickness of the polyethylene insert; the material of the femoral head; and the relationship of the cervical–diaphyseal morphology of the proximal end of the femur to the restoration of the femoral offset. In all 72 simulations studied, a difference was observed in favour of a cemented solution with respect to the risk of wear. With regard to the other variables, the acetabular fixation, the thickness of the polyethylene, and the acetabular component positioning were statistically significant. The highest values for the risk of wear corresponded to a smaller thickness (5.3 mm), and super-lateral positioning at 25 mm reached the highest value of the von Mises stress. According to our results, for the reconstruction of the acetabular side, a cemented insert with a thickness of at least 5 mm should be used at the center of rotation.