Metal On Metal Total Hip Replacement After Cobalt Chrome Molybdenum Released Preliminary Study

Objectives:To explore the changes of cobalt chromium and molybden- um concentration in the plasma of patients after metal on metal total hip replacement.Methods:Metal on metal total hip replacement occurred in 10 cases who were admitted as experimental group,8 cases after knee replacement were admitted as contrast group.Patients in experimental group were26-65 years old,average(47.8±11.91years).six male cases(six hips)and four female cases(five hips)were found in experimental group,four cases (four hips) suffered from osteoarthritis,three cases(four hips)suffered from aseptic necrosis of the femoral head,femoral neck fracture occurred in two cases (two hips),femoral head giant cell tumor occurred in one case(one hip). Patients after knee replacement in contrast group aged64-86years old,the average age(74.25±7.02years),there were one male(one knee) and seven females(eight knees)in contrast group.2ml venous blood samples were collected before operation,2nd week,6th week,12th weeks,24th weeks after operation,Concentration of Chromium(Cr),cobalt(Co)and molybdenum (Mo) ions in the plasma samples were measured.All the patients were followed up in the preoperative and postoperative period,X-ray was recorded, high- resolution(300dpi)optical scanner was admitted to measure hip CEangle Sharp Point,neck stem Kok and acetabular Coverage.Imagika software was used to deal with data. Past other metal implants are not involved in this study.Results:(1)Cobalt-chromium ion levels in the plasma after in High- carbon content of metal on metal hip and knee replacement were significan- tly higher(multivariate analysis of duplication,p<0.001),dominant elevation changes were found from 2to6weeks after operation,the highest concentr- ation of ions occurred in six weeks(hip:Co-16.49ug/L;knee:Co-31.12ug/L), six weeks after the ion concentration in gradually declining trend in the plasma after about 12weeks after declining to The level of two weeks to 24 weeks after Ion downward trend gradually slow down.(2)Cobalt,chromium ion concentration in hip replacement group were lower than those in knee. (3)Cobalt and chromium ion concentration in male cases was significantly higher than those of women(p<0.01).(4)Replacement group ion concentrat ion of forging products were lower than casting products (p<0.01).(5)No significant changes was found in molybdenum there (Pearson correlation coefficient p=0.0934)Conclusion:(1)The concentration of cobalt-chromium and cobalt ion after metal on metal total hip replacement and knee replacement were elevated dominantly.The cobalt concentration after 2 weeks of operation is 7.88 times larger than that before operation,The chromium ion concentration after 2 weeks of operation is 10.89 times larger than that before operation,no significant changes occurred about Mo ion concentration (2)Cobalt-chromium ion concentration in total hip replacement group was lower than those of knee replacement.(3)Replacement group ion concentrat ion of forging products were lower than casting products.(4)Total hip replacement group of men after the release of cobalt-chromium ion concentration greater than female patients.