Analysis of a Lane-plate internal fixation device after 64 years in vivo.

A patient presented for an above-knee amputation 64 years after successful internal fixation of a femoral fracture with a Lane plate. Chemical analyses of the plate and corrosion products were done using atomic absorption spectrophotometry, x-ray energy spectroscopy and x-ray diffraction. Mechanical properties of the fixation devices were measured using Rockwell-type instruments and metallographic analyses were also performed. In addition, pathologic and radiologic investigations of the underlying bone were carried out. Results disclosed that extensive corrosion had weakened the plate by 50%. The metallosis of the surrounding soft tissues and abnormal morphologic features of underlying bone were analysed. No appreciable cellular inflammatory or dysplastic reaction of adjacent tissues was identified. The underlying bone showed a persistent lack of mature compact bone and no evidence of remodelling. The products of corrosion were mainly ferrous carbonate and some ferrous chloride. The mechanism of the corrosion was the formation of a galvanic cell between the iron carbide and surrounding iron, with dissolution of the iron and formation of the corrosion products.