Metalosis en prótesis total de cadera modelo PM A propósito de 1 caso

Resumen.—Se presenta el caso de 1 paciente con aflojamiento aseptico de una protesis de cadera modelo PM. En el recambio, efectuado a los 7 anos de seguimiento, se observo una severa metalosis, con presencia de un pigmento negro que invadia toda la capsula y rodeaba el vastago y cotilo protesico. Se muestran las imagenes anatomapatologicas con histiocitos cargados de parti­ culas metalicas de pequeno tamano. Resaltamos la clinica insidiosa y la ausencia radiografica de lisis osea, todo ello distinto a los hallazgos descritos en aflojamientos asepticos debidos a particu­ las de polietileno. La causa de la metalosis fue el rozamiento del cuello del vastago femoral sobre el reborde inferior del acetabulo metalico. METALLOSIS AFTER TOTAL HIP REPLACEMENT USING PM MODEL Summary.—We report a case of a patient who had aseptic loosening of a total hip prosthesis model PM. At revision we found severe metallosis. A black surgery, seven years after the device was implanted pigment that penetrated the capsule and sorrounded the femoral and acetabular com­ ponents was found. Histological examination of a the specimen of capsular tissue showed histiocytes loaded with small size metallic particles. Of particular interest was the absence of severe clinical and radiological changes. These finds are unusually associated with aseptic loosening niade by polymeric wear debris. The reason of metallosis was supposed tobe the friction between the neck of femoral component and lower rim of the acetabular component.