A clinical and metallurgical analysis of retrieved Jewett and Richards hip plate devices.

The metallurgical properties of 61 retrieved 316L stainless steel (ASTM F138-76) hip plate devices used for the treatment of intertrochanteric fractures were examined. Surface and screw-plate interface corrosion characteristics were graded, and grain size, inclusion content, and hardness values were measured. These measurements were then correlated with the clinical performance of the devices. The devices studied included 21 Jewett nail-type and 40 Richards compression screw-type hip plates. The devices had been in situ an average of 26.7 months, with in situ periods ranging from 2.0 to 156.0 months. Cause-related reasons represented the majority of removals (89.8%), while only 10.2% of the hip plates were removed on a routine asymptomatic basis. The data suggest that surgeons consider this type of device as a permanent implant, with removal undertaken only for causative factors. Of all devices removed, 30.6% were retrieved from patients who presented with fracture nonunion. Upon microscopic examination, 97% of the retrieved implants exhibited some degree of either surface of interface corrosion. Statistical analysis revealed significant correlations between corrosion scores and the metallurgical properties of grain size and nonmetallic inclusion content. No statistically significant metallurgical or corrosion differences were discerned between the two types of devices studied. However, four implants of the Jewett design and four of the Richards design were found to be out of ASTM specification F-138-76. It should also be noted that four devices of the Jewett design (19%) fractured in situ, while none of the retrieved Richards designs had fractured. No correlation was observed between the plates' corrosion scores and in situ time.(ABSTRACT TRUNCATED AT 250 WORDS)