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Objective To observe the influence of low or middle power microwave radiation on tissues adja-cent to titanium alloy implants. Methods Titanium alloy internal fixation plates were implanted into the upper femur of the right side of New Zealand white rabbits, the left femurs served as the control. Then the femurs were exposed to 20, 40, 60, or 80 W of microwave radiation at a frequency of 2450 MHz for 30 minutes, and real-time temperature of the implants and its adjacent muscles were recorded. The nerve conduction study of the sciatic nerve was performed by stimulating the nerve and recording from gastrocnemius in both groups. Finally, all the rabbits were sacrificed and histo-logical studies were performed on nerve and muscle sections. Results Compared to the control limbs, temperatures of limbs with titanium alloy implants increased significantly when exposed to microwave radiation at 60 and 80 W ( P0.05). Pathological examination showed obvious congestion and bleeding in the intercellular spaces of skeletal muscle cells in the experiment group when exposed to radiation at 60 W, with no ob-vious pathological changes found in the sciatic nerve. However, when exposed to radiation at 80 W, vacuoles appeared in myocytes, the cellular structure was destroyed and the myelin sheath of the sciatic nerve swelled. Conclusion Ex-posure to microwave irradiation at 20 and 40 W, but not 60 and 80 W exerts no adverse effects on nerves and muscles adjacent to titanium alloy internal fixation plates. Consequently, continuous wave microwave irradiation at low powers (20~40 W) is a safer auxiliary treatment for limbs with titanium alloy implants.
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Las reacciones cutáneas a implantes metálicos, ortopédicos u otros, están bien documentadas en la literatura. Las reacciones de hipersensibilidad al metal de los dispositivos implantados siguen siendo un tema difícil y controvertido. Los criterios y los métodos de diagnóstico no están completamente delineados aún. Hay incertidumbresy desacuerdos sobre el papel causal de la sensibilidad al metal en el funcionamiento deficiente o ante implantes fallidos. La opinión, casi de consenso, es que las pruebas del parche deben ser consideradas para los pacientes con sospecha de hipersensibilidad al metal previo al implante y en las personas con sospecha de reacciones a los mismos. Presentamos dos pacientes con sensibilidad a implantes metálicos.
Skin reactions to metal or other orthopedic implants are well documented in the literature.Hypersensitivity reactions to metal implanted devices remains a difficult andcontroversial subject. The criteria and diagnostic methods are not yet fully delineated.In addition there are uncertainties and disagreements about the causal role ofmetal sensitivity in poor performance or implant failure. The current opinion, almostconsensual, is that patch testing should be considered for patients with suspectedhypersensitivity to metal prior to implantation and those with suspected reactions tothem. We are introducing two patientsthat developed contact dermatitis secondaryto metal implants.
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Humanos , Hipersensibilidade , Próteses e Implantes , Testes do EmplastroRESUMO
ObjectiveTo investigate the impact of metal plate on radiation dose distribution by Monte Carlo (MC) code. MethodsThe metal plates with 0. 4 thick were placed in water at 5 cm, all the plate irradiated with 6 MV X-ray were simulated by MC code, SSD =100 cm. The percentage depth dose with or without metal implants were compared. ResultsThe surface absorbed doses on incident plane of stainless steel plate and titanium plate were increased by 19. 6％ and 15.7％ respectively as compared water,the dose influence was less than 1.5％ more than 0. 3 cm outside the incidence plane. The doses on the exit surface of stainless steel plate and titanium plate were lowered by 8. 6％ and 8. 2％ when compared with water, the dose impacts of this places where were from the exit surface of stainless steel plate 、titanium plate more than 1.2 cm,0. 9 cm were less than 1.5％. The surface absorbed doses on incident plane of stainless steel plate were increased by 3.9％ respectively as titanium plate, the dose of the exit surface of stainless steel plate and titanium plate was similar. Conclusions MC method is a fast and accurate calculation method. The influence of metal plate on the radiotherapy dose distribution is significant. Under the such condition, the impact of stainless steel plate is much more than that of titanium alloy plate.
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Objective To investigate the impact of metal plate on radiation dose distribution in surrounding tissues in cadaver specimens.Methods Stainless steel plate, titanium plate, and muscle strip were implanted into the left thigh of a corpse, respectively.All the specimens were irradiated with 6 MV X-ray , SSD = 100 cm.The absorbed dose of surface was measured by thermoluminiscent elements.Results Surface dose distributions differed significantly among the three different materials (F = 57.35, P < 0.01),with the amounts of 1.18 Gy ± 0.04 Gy (stainless steel plate), 1.12 Gy ± 0.04 Gy (titanium plate) and 0.97 Gy ±0.03 Gy (muscle strip), respectively.The surface absorbed doses on incident plane of stainless steel plate and titanium plate were significantly increased by 21.65% and 15.46% respectively as compared with that of muscle strip.The absorbed doses on the exit surface of stainless steel plate, titanium plate and muscle strip were 0.87 Gy ± 0.03 Gy, 0.90 Gy ± 0.02 Gy and 0.95 Gy ± 0.04 Gy, respectively (F =13.37, P <0.01).The doses on the exit surface of stainless steel plate and titanium plate were significantly lowered by 8.42% and 5.26% when compared with that of muscle strip.Using treatment planning system,the differences between dose distribution with and without metal plate were compared.Within 1 cm away from the incident plate, there was an obvious increase in the absorbed dose, while the influence was less than 5% 1cm outside the surface.The effect of dose distribution on exit surface was less than 2%.Conclusions The influence of metal plate on the radiotherapy dose distribution is significant.The deviations ranges from 5% to 29%.Under the same condition, the impact of stainless steel plate is much more than that of titanium alloy plate.
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Biomaterials for medical use have been developed in accordance with progress of the fields of medicine, biochemistry, material science, and pharmaceutics. Advances in the medicine have changed the concept of surgery from the deletion of damage tissue for the preservation of the remaining healthy tissue to the reconstruction or replacement of damaged tissue by promoting regeneration of the natural tissue. All the materials used in medicine should be biocompatible. Conventional materials such as metals, ceramics, and synthetic polymers are usually bioinert and support the structural defects. But recently introduced biomaterials are designed to provide biological functions as much a possible by mimicking natural tissue structures.