Pressure side and tension side comminution of femoral neck cortex are independent risk factors for aseptic necrosis after femoral neck fracture surgery / 中国骨伤

OBJECTIVE@#To investigate the related factors of aseptic necrosis of femoral head after closed reduction and internal fixation of femoral neck fracture.@*METHODS@#From January 2009 to January 2016, 236 patients with femoral neck fracture were treated with closed reduction and internal fixation with 3 hollow lag screws, including 111 males and 125 females, aged from 19 to 89 (50.17±12.88) years. According to the follow-up results, the correlation of aseptic necrosis of femoral head was analyzed. Univariate analysis of age, gender, injured side, body weight, injury mechanism, preoperative waiting time, Garden classification and whether there was comminution of femoral neck cortex was conducted to obtain the independent variables with significant difference. Then binary logistic regression analysis was conducted to explore the independent risk factors of avascular necrosis of femoral head.@*RESULTS@#The average follow-up period of 236 cases was 4.58 years. There were significant differences in the range of injury (24.69% vs. 5.16%, @*CONCLUSION@#High energy injury, preoperative waiting time (>48 h) and comminution of femoral neck cortex were independent risk factors for aseptic necrosis of femoral head. In addition, cortical comminution on the pressure side and tension side of the femoral neck is a strong prognostic risk factor for aseptic necrosis of the femoral head, because it indicates a more serious and complex injury mechanism.

Development of shear force-induced intervertebral disc degeneration model / 医用生物力学

Objective To develop a shear force-induced intervertebral disc degeneration (IDD) in vivo animal model, and investigate the relationship between shear stress and IDD. Methods A total of 20 Japanese white rabbits were randomly divided into two groups. In loading group (n=10), shear force of 50 N was applied on the disc of L4/5 for 4 weeks by a custom-made external shear force loading device. In control group (n=10), the animals underwent a sham operation with the external loading device situated, but their discs remained unloaded. After 4 weeks, all the intervertebral discs of L4/5 were executed for the pathologic examination. Results The postoperative radiographic examination showed a perfect position of the loading device, and the operation process and implanted loading device had no effect on daily activities and diet of the experiment animals. The pathological examination showed an irregular arrangement of annulus fibrosus and a significant decrease of normal nucleus pulposus cells in loading group. Conclusions The new custom made device greatly reduced the wounds on animal vertebra and provided a reliable shear force. The development of in vivo animal model indicates that IDD can be induced by shear force, which is of significance to further study the relationship between loading and IDD.