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- Author or Editor: Stefan Milz x
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Objective—To determine the material properties of Slocum TPLO plates and assess the soft tissue reaction adjacent to these plates in dogs that had undergone tibial plateau leveling osteotomy (TPLO).
Sample Population—3 new TPLO plates, 8 retrieved TPLO plates, and 1 new Synthes dynamic compression plate.
Procedures—Metallurgic analyses were performed. Tissue samples were obtained from areas adjacent to retrieved plates and submitted for histologic examination.
Results—All of the TPLO plates had a 2-phase microstructure consisting of austenite and ferrite in various amounts. Residua, inclusions, and cavities were seen during microscopic examination of the plate surface. The major differences between new and retrieved TPLO plates were the presence of small gaps separating many inclusions from the surrounding matrix and the presence of various-sized pits on the surface of the retrieved plates. The dynamic compression plate had a nearly pure austenitic structure and was largely free from residua, inclusions, and cavities. Histologic examination of tissue samples obtained from areas adjacent to retrieved TPLO plates revealed intra- and extracellular particulate debris. Two types of particles (one consisting of chromium, nickel, molybdenum, and iron and the other consisting of aluminum and silicon) were seen.
Conclusions and Clinical Relevance—Results determined that new and retrieved TPLO plates were manufactured from 316L stainless steel and produced by a casting process, but not all plates met specifications for chemical composition of cast surgical implants (American Society for Testing Materials standard F745); tissues surrounding retrieved plates had evidence of adverse reactions, probably as a result of plate corrosion.
OBJECTIVE To evaluate and compare surface and cross-sectional structure as well as localized electrochemical corrosion and ion release for cast stainless steel (SS) tibia plateau leveling osteotomy (TPLO) plates retrieved from dogs with and without osteosarcoma (OSA) and to compare these findings with similar variables for forged SS TPLO plates retrieved from dogs.
SAMPLE 47 TPLO plates explanted from 45 client-owned dogs (22 cast plates from dogs with OSA, 22 cast plates from dogs without OSA, and 3 forged plates from dogs without OSA).
PROCEDURES Histologic evaluations of tissue samples collected from implant sites at the time of plate retrieval were performed to confirm implant site tumor status of each dog. Surfaces and metallographic cross sections of retrieved plates were examined, and the microcell technique was used to obtain local electrochemical corrosion and ion release measurements.
RESULTS Findings indicated that all cast SS plates demonstrated high spatial variability of their electrochemical surface properties and inhomogeneous superficial and cross-sectional composition, compared with forged plates. Greater metal ion release was observed in cast plates than in forged plates and in cast plates from dogs with OSA than in cast or forged from dogs without OSA.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that accumulation of metal ions from implants could be a trigger for neoplastic transformation in neighboring cells. Metal ion release caused by corrosion of implants that do not comply with recommended standards of the American Society for Testing and Materials International or the International Organization for Standardization could potentially place patients at increased risk of tumor development.