Clinical Study Of A New Type Of Biodegradable Magnesium Internal Fixation Screws For Repairing Osteonecrosis Of The Femoral Head

Objective: To investigate the safety and efficacy of a new type of biodegradable magnesium internal fixation screw for vascularized iliac bone flap transplantation in osteonecrosis of the femoral head(ONFH).Methods: Patients with ONFH admitted from July 2020 to February 2021 were selected as the research objects,and 20 patients(20 hips)met the selection criteria and were included in the study.The patients were divided into two groups(n=10)by central random method.The iliac bone flap was fixed with a new biodegradable magnesium internal fixation screw in the experimental group,and the iliac bone flap was wedged directly in the control group.There was no significant difference in gender,age,side,ONFH side,type,ARCO stage and course of disease between the two groups.The operation time and intraoperative blood loss of the two groups were recorded.Laboratory tests were performed at each time point before and after operation,including white blood cell(WBC),electrolytes(potassium,calcium,phosphorus,magnesium),blood urea nitrogen(BUN),serum creatinine(Scr),glomerular filtration rate(e GFR),lymphocyte ratio(CD4/CD8),Immunoglobulin G(Ig G),Immunoglobulin M(Ig M),Alanine transaminase(ALT),Aspartate aminotransferase(AST);After operation,Harris score was used to evaluate the hip joint function.CT of the hip joint and DR films in anteroposteric and frog positions of the pelvis were used to review the bone flap position,fusion and screw biodegradation in the experimental group.Results: The vital signs of the two groups were stable,the incisions healed by first intention,and no adverse events occurred.One patient in the control group refused to return to the hospital for follow-up 3 months after operation,and one patient in the experimental group refused to return to the hospital for follow-up 12 months after operation.The rest of the patients completed the follow-up 3,6,and 12 months after operation.Laboratory tests showed that there were no significant differences in WBC,K,Ca,P,Mg,BUN,Scr,e GFR,CD4/CD8,Ig G,Ig M,ALT,AST between the two groups at each time point before and after surgery(P>0.05).The operation time and intraoperative blood loss of the experimental group were lower than those of the control group,and the differences were statistically significant(t=-2.647,P=0.016;T =3.351,P=0.004).There was no significant difference in Harris score between the two groups at 6 months after operation and before operation(P >0.05).12 months after operation was higher than that before operation,the difference was statistically significant(P < 0.05).There was no significant difference between the two groups at each time point(P>0.05).Postoperative CT of hip joint and DR films of pelvis in anterograde and frog position showed that the iliac bone flap reached osseous fusion with the fenestration of the head and neck junction of femoral head in both groups at 12 months after operation,and no loosening or shedding of graft was observed during follow-up.In the experimental group,there were signs of dissolution and absorption of the new biodegradable magnesium internal fixation screws after operation,and no screw breakage and detachment were observed during follow-up.Conclusion(s): In the treatment of ONFH with vascularized iliac bone flap grafting,the new biodegradable magnesium internal fixation screw is used to fix the iliac bone flap firmly during the operation.Compared with the traditional iliac bone flap wedging directly,the operation time is shorter,the bleeding is less,and the similar joint function can be obtained.