CLINICAL AND METALLURICAL EXAMINATION OF INTERNAL FIXATION DEVICES.

As part of an on-going implant retrieval and analysis program, the clinical performance, corrosion characteristics, and the metallurgical properties of 61 bone plates have been studied. These implants were all fabricated from 316L stainless steel. Medical histories were obtained from each patient, including the clinical history at the time of removal. Each of the retrieved implants was cleaned, photographed and examined under a stereomicroscope for evidence of corrosion and mechanical damage. The screw-plate interface corrosion was examined and graded on a scale of 0-5, where 0 indicated no corrosion and 5 indicated the presence of very severe corrosion. The results of this study demonstrate that a high percentage of the devices are performing unsatisfactorily at all time periods. This was due, no doubt, in some part to the significant corrosion exhibited by the stainless steel material used to fabricate the devices. The need for corrosion reduction is apparent. It is possible to reduce the degree of corrosion by the use of a smaller grained and microscopically cleaner 316L stainless steel in the manufacture of these devices. Therefore, higher standards for the stainless steel used for implant devices and higher quality control by the manufacturer seems appropriate. Our data suggests a standard of 7. 5 or finer for the grain size and no more than 1. 0 for the thin inclusion content as an improvement over the current ASTM standard (F138-76).