Finite element optimization analysis of minimally invasive screw treatment for Sanders typeⅡcalcaneal fracture / 中国骨伤

OBJECTIVE@#To explore biomechanical characteristics of minimally invasive different screw fixations in treating Sanders typeⅡcalcaneal fractures.@*METHODS@#Dicom data of calcaneus by CT scan were input into Mimics 21.0 software and Ansys15.0 software to construct three-dimensional finite element digital model of calcaneus;this model was input into UG NX 10.0 software, and calcaneus was cut according to Sanders classification to establish Sanders typeⅡ calcaneus model with posterior articular surface collapse;then simulated minimally invasive screw internal fixation after calcaneal fracture:a screw from posterior articular surface was used to outside-in fix sustentaculum tali, other 4 screws were used to fix calcaneus by different methods through calcaneal tuberosity, and 4 different calcaneal models were obtained. Under the same conditions, 4 types of internal fixation models were loaded respectively, and nonlinear finite element analysis was performed to calculate the stress distribution of different internal fixation models.@*RESULTS@#Under the same condition of loading, the model 3 had smaller displacement value, maximum calcaneus displacement value and maximum equivalent stress value of the screw than other three internal fixation models, and the stress was more dispersed.@*CONCLUSION@#In minimally invasive screw internal fixation of calcaneus fracture, after 1 sustentaculum tali screw fixation, 2 screws crossed fix posterior articular surface from calcaneal tuberosity, 2 screws fix parallelly calcaneocuboid joint from calcaneal tuberosity are more suitable for biomechanical requirements, and could provide basic theory for clinical treatment.

biomechanical study of rupture of achilles tendon and repair by different suture techniques

Objective: To study the biomechanical properties of different suture methods, and to provide evidence for the clinical application of this suture methods in repairing acute Achilles tendon rupture

Methods: Twenty four fresh frozen cadaver Achilles tendon specimens were collected and randomly divided into three groups [n=8], Group-A Bunnell suture method, Group-B Bosworth suture and Group-C anchor suture respectively. 5 N tensions were applied to tighten the tendon. The actual length of the tendon between the upper and lower clips was measured with a ruler. The length of the long axis and the short axis of the three sections of the tendon was measured by vernier caliper. The cross sectional area of the tendon was calculated according to the elliptical area formula and the mean value was obtained

Results: There was no significant difference in the length and cross-sectional area of each tendon among three groups [F=0.26, P=0.86; F=0.09, P=0.96]. There was no significant difference in the maximum load of tendon and failure displacement in Group A and B [P>0.05]. The maximal load of Group-C was significantly larger than that of Group A and B [P<0.05], and there was no significant difference between the failure displacement and Group A and B [P>0.05]

Conclusion: Three suture methods can provide good biomechanical properties, but the anchor suture is more effective in solving the shortcomings of traditional methods. It is a safe and effective method, and is worthy of promotion

Functional outcome of tarsometatarsal joint fracture dislocation managed according to myerson classification

To summarize the functional outcome of tarsometatarsal joint fracture-dislocation managed according to Myerson classification. Total eighty cases of tarsometatarsal joint fracture-dislocation were treated from Mar 2004 to Feb 2012. According to the Myerson classification, there were 14 cases in type A, 12 cases in type B1, 28 cases in type B2, 11 cases in type C1 and 15 cases in type C2. All the cases were treated with open reduction and internal fixation and the incisions and implants were also selected according to the Myerson classification. X-ray was examined during the follow-up period and functional evaluation was carried out by American Orthopaedic Foot and Ankle Society [AOFAS] midfoot score system. Analysis of variance was used to test the different types of Myerson classification. Sixty eight patients got a mean follow-up of 24 months [15-36 months]. No patient suffered from infection, skin flap necrosis and X-ray showed there were no implants loosening or breakage. The mean AOFAS score was 88.4[47-100] and excellent and good result was 89.7%. The differences among Myerson classifications showed that there were statistical significance between type B and type A, type C [P < 0.05] Three patients suffered from severe pain and difficult walking, X-ray showed the ambiguity of the joint space, which can be diagnosed as posttraumatic arthritis. One patient had arthrodesis finally. The Myerson classification is helpful to make preoperative plan and judging prognosis to the tarsometatarsal joint injuries. In type B, single or double incisions with screw or plate fixation is enough, while in type A and type C, double or triple incisions with screw or plate fixation in medial joints and Kirschner wire fixation in lateral joints are needed. Postoperatively, the type B patients had better prognosis than type A and type C patients. However, the concomitant injuries around the tarsometatarsal joint were not included in Myerson classification, which is the limitation but cannot be neglected

Effect of profound hypothermia on cytochrome C release and cell apoptosis in the hippocampus after global ischemia in rats / 中华神经医学杂志

Objective To detect the effect and role of profound hypothermia on cytochrome C release and cell apoptosis in the hippocampus after global ischemia in rats. Methods We established the animal model of cardiopulmonary bypass (CPB) in 24 rats which were randomized into 3 even groups:blank control group,normothermia ischemia group and hypothermia ischemia group.After the hippocampus samples were harvested from the 3 groups,Western blot was used to detect the expression of cytochrome C (Cyt-C) and TUNEL was used to measure the cell apoptosis. Results The expression of Cyt-C in the normothermia ischemia group increased significantly compared with the blank control group but decreased significantly compared with the hypothermia ischemia group (P＜0.05).The rate of cell apoptosis in the normothermia ischemia group increased significantly compared with the blank control group but decreased significantly compared with the hypothermia ischemia group (P＜0.05).Conclusions Profound hypothermia can inhibit cytochrome C release into the cytoplasm and thus reduce cell apoptosis in the hippocampus after global ischemia in rats. This may be one important mechanism underlying the protective effect of profound hypothermia.

Inhibition of NHE-1 mRNA expression in penumbra area by human interleukin-10 transfection following cerebral ischemia-reperfusion injury in rats / 中华神经医学杂志

Objective To explore the effect of SA liposome mediated human interleukin-10 (IL-10) gent transfection on NHE-1 mRNA expression in penumbra area following focal cerebral ischemia reperfusion injury in rats. Methods Totally 78 male SD rats were randomly divided into normal control group (n=6), MCAO group (n=24), hIL-10 transfection group (n=24) and empty vector transfection group (n=24). Longa's method was employed to establish MCAO models in the latter 3 groups. The rats in the MCAO group underwent stereotactic operation without drug injection, and the hIL-10 transfection group and empty vector transfection group were injected stereotactieally with pcDNA3.1-IL-10 and pcDNA3.1, respectively, both by SA liposome mediation. After transfection, RT-PCR and ELISA were used to determine the effect of transfection, TTC staining was conducted to detect the infarct volume. Meanwhile, real-time quantitative PCR was performed to examine the expressions of NHE-1 mRNA and NF-κB mRNA in the penumbra area. Results (1) SA liposome effectively mediated the hIL-10 gene to transfect the brain tissue. Also hIL-10 gene transfection played neuroprotective effect by reducing the brain infarct volume. (2) The expression of NF-κB mRNA in different groups was 1.00±0.33, 4.76±0.41, 4.58±0.62 and 2.77±0.43, respectively, hIL-10 gene transfection also inhibited the increase of NF-κB mRNA expression in the penumbra area following the cerebral ischemia reperfusion injury. (3) The expression of NHE-1mRNA was 1.00±0.22, 4.16±0.48, 3.97±0.51 and 2.82±0.47, respectively, hIL-10 gene transfection also inhibited the increase of NHE-1 mRNA expression in the penumbra area following the cerebral ischemia reperfusion injury. Conclusions The hIL-10 transfection can exert the protective effect on the brain against cerebral ischemia-reperfusion injury partly via inhibiting the NHE-1 mRNA expression.