[Clinical study of a new biodegradable magnesium internal fixation screw in treatment of osteonecrosis of the femoral head].

Objective: To investigate the safety and efficacy of a new biodegradable magnesium internal fixation screw for vascularized iliac bone flap grafting in treatment of osteonecrosis of the femoral head (ONFH). Methods: Patients with ONFH admitted between July 2020 and 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 trial group, and the iliac bone flap was wedged directly in the control group. There was no significant difference ( P>0.05) in gender, age, and side, type, Association Research Circulation Osseous (ARCO) stage, and disease duration of ONFH 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 (K, Ca, P, Mg), blood urea nitrogen (BUN), serum creatinine (Scr), glomerular filtration rate (eGFR), lymphocyte ratio (CD4/CD8), immunoglobulin G (IgG), IgM, alanine transaminase (ALT), aspartate aminotransferase (AST). After operation, Harris score was used to evaluate the hip joint function. CT of the hip joint and X-ray films in anteroposterior and frog positions of the pelvis were used to review the iliac bone flap position, fusion, and screw biodegradation in the trial group. Results: The vital signs of the two groups were stable, the incisions healed by first intention, and no adverse events occurred after operation. One patient in the control group refused to return to the hospital for follow-up at 3 months after operation, and 1 patient in the trial group refused to return to the hospital for follow-up at 1 year after operation. The rest of the patients completed the follow-up at 2 weeks, 3 months, 6 months, and 1 year after operation. Laboratory tests showed that there was no significant difference in WBC, electrolytes (K, Ca, P, Mg), BUN, Scr, eGFR, CD4/CD8, IgG, IgM, ALT, and AST between the two groups at each time point before and after operation ( P>0.05). The operation time and intraoperative blood loss of the trial group were significantly less than those of the control group ( P<0.05). The Harris scores of the two groups at 1 year significantly increased when compared with the values before operation and at 6 months after operation ( P<0.05). There was no significant difference in Harris score between the two groups at each time point ( P>0.05). Postoperative CT of hip joint and X-ray films of pelvis showed that the iliac bone flap reached osseous fusion with the fenestration of the head and neck junction of femoral head in the two groups at 1 year after operation, and no loosening or shedding of iliac bone flap was observed during follow-up. In the trial group, there were signs of dissolution and absorption of the new biodegradable magnesium internal fixation screws after operation, and the diameter of the screws gradually decreased ( P<0.05); no screw breakage or detachment occurred during follow-up. Conclusion: In the treatment of ONFH with vascularized iliac bone flap grafting, the new biodegradable magnesium internal fixation screws can fix the iliac bone flap firmly. Compared with the traditional iliac bone flap wedging directly, it has a shorter operation time, less intraoperative blood loss, and can obtain similar joint function.

[Application of a new temporary intravascular shunt device in limb injury of dogs].

OBJECTIVE: To explore the effectiveness and safety of a new temporary intravascular shunt (TIVS) device for limb injury in dogs. METHODS: Eighteen adult beagle dogs, male or female, weighing (20±2) kg, were taken for experiment. A semi-amputated limb model was made by circular amputating the knee joint of one hindlimb, which retained only skin, femoral artery, femoral vein, femoral nerve, and femur. Then the femoral artery was clamped for 2 hours in all animals, resulting in the ischemic environment of the distal limbs. The animals were randomly divided into 3 groups ( n=6). In group A, the bypass was started by using a new TIVS device and replenishing saline through the infusion port; In group B, after intravenous injection of heparin sodium solution, the bypass was started by using a new TIVS device and replenishing 3% heparin sodium solution through the infusion port; In group C, the bypass was started by using the self-made bypass tube. The bypass was end after 12 hours. The general vital signs (body temperature, heart rate, blood pressure) before and after bypass were measured, and the time required for the insertion of the bypass tube, the patency during the bypass, shedding, and thrombosis were recorded. Routine blood test and blood coagulation indicators [white blood cell (WBC), red blood cell (RBC), platelet (PLT), hemoglobin (HGB), activated partial thromboplastin time (APTT), fibrinogen (Fib)] and biochemical indicators [lactic dehydrogenase (LDH) and creatine kinase (CK)] were recorded before bypass and after 3, 6, 9, and 12 hours of bypass, respectively. The gastrocnemius muscles on the surgical side before and after bypass were harvested and the muscle necrosis, the wet-to-dry weight ratio, and the content of malondialdehyde (MDA) and myeloperoxidase (MPO) were measured. In addition, the gastrocnemius muscle and femoral artery were observed after bypass by HE staining. RESULTS: There was no significant difference in body temperature, heart rate, and blood pressure between groups before and after bypass ( P>0.05). Compared with groups A and B, the time required for the insertion of the bypass tube in group C was significantly longer ( P<0.05), and the number of thrombus in the bypass tube, the blockage time significantly increased ( P<0.05). Shedding and sliding of bypass tube occurred in 3 cases of group C, but no shedding or sliding of bypass tube occurred in groups A and B; there was no significant difference in the incidence of shedding between groups ( P=1.000). There was no significant difference ( P>0.05) in routine blood test, blood coagulation indicators, LDH, CK, MPO, MDA, and wet-to-dry weight ratio between groups before bypass. After bypass, the routine blood test and blood coagulation indicators of the 3 groups did not change significantly, and the differences between groups was not significant ( P>0.05); LDH and CK gradually increased ( P<0.05), and group C significantly higher than groups A and B at 12 hours ( P<0.05). After bypass, thrombosis was seen in the bypass tube, the distal gastrocnemius muscle necrosis occurred in group C, and the femoral artery injury was slightly heavier than that in groups A and B. CONCLUSION: The new TIVS device is safe and effective and has the advantages of convenient implantation, lower thrombosis rate, and less limb ischemia-reperfusion injury.