BACKGROUND:At present,there are many established femoral finite element studies,but previous studies focused on femoral biomechanics of the outside are few.OBJECTIVE:To establish three-dimensional finite element model of structure of the proximal femur,and to analyze its biomechanics in normal standing position to provide reasonable evidence for clinical application.DESIGN,TIME AND SETTING:A three-dimensional finite element model analysis was performed in General Hospital of Tianjin Medical University from December 2008 to April 2009.PARTICIPANTS:One male volunteer aged 30 years was enrolled at General Hospital of Tianjin Medical University.Femur lesion or injury was excluded by means of X-ray.METHODS:The primitive femur CT data were adopted according to Dicom 3.0 standard in Mimics so as to obtain the primitive three-dimensional femur model which was established via threshold defining,region enlarging and morphological performing.The primitive model was remeshed and combined with ANSYS software to create a final finite-element model.The model obtained by using the Mimics was loaded with 200 N vertical loading to check out the difference of the stress distribution.MAIN OUTCOME MEASURES:Using 200 N as the external load in the vertical direction,the Vonmises stress distribution of the femur was detected.RESULTS:The applications of Mimics and Ansys software could create a finite element model of proximal femur.It was found that the correspondent relationship between stress and structure in proximal femur was verified.CONCLUSION:Mimics can build more three-dimensional finite element models in line with the proximal femoral mechanical structure and mechanical properties.The mechanical properties of the femur are more credible,and the results of the analysis support the clinical application of the guidance.

Objective To establish a three-dimensional finite element model of thoracolumbar fractures treated by mono-segmental instrumentation in the fractured part for testing effect of such fixation mode on adjacent segments.Methods CT scanning data of T10-L2 were used to build a normal model at T10-L2 region,a fracture model at T12 segment as well as a mono-segment fixation or short-segment fixation model.Stress of discs and vertebral body adjacent to the fixed vertebrae were tested in axial compression,anteflexion,extention,lateroflexion,and axial rotation.Results The fracture model presented significant increase concerning stress of nucleus pulposus and annular fibrosus at T10-T11 segments and annular fibrosus at L1-L2 segments in anteflexion,extention,and lateroflexion when compared with the normal model.General raise range of the stress reached around 75％,but was dropped to 23％ after short-segment fixation and to 18％ after mono-segmental fixation.And again,stress of nucleus pulposus at L1-L2 segments was increased by 46％ or so,which was declined to 12％ after short-segment fixation and to 8％ after mono-segmental fixation.Stress at lower endplate of T10 and at upper endplate of L2 in the fracture model group were increased by 24％ and 43％ respectively when compared to the normal model,but both presented a notable drop after internal fixation.The latter was decreased to a level slightly higher than that of model group,namely 8％ more after short-segmental fixation and 4％ more after mono-segmental fixation; the former was decreased to a level even lower than that of control group,namely 2％ less after short-segmental fixation and 8％ less after mono-segmental fixation.Conclusion Mono-segmental fixation reduces adjacent disc stress in contrast to conventional short-segmental fixation and hence is an effective alternative treatment of monosegmental thoracolumbar fractures.

OBJECTIVE To investigate the time and dose relation of new urine bio markers in rat model of acute kidney injury induced by genta mycin (GM)to search for more sensitive,noninvasive and specific markers than traditional approaches to monitor nephrotoxicity.METHODS SD Rats were im treated with GM5,20,80 mg·kg -1 or saline once daily.Rats were randomly divided into 20 subgroups:treated for 1 ,3,7,14 d and 14 d followed with 28 d recovery period.Ten rats per group (5 rats per sex)were scarified at 24 h after the last dosing or the end of recovery period.Blood sa mples were col-lected for blood urea nitrogen (BUN)and creatinine(CRE)analysis.Urine was collected at each nec-ropsy for urine protein by dry che mistry method,for kidney injury molecule-1 (KIM-1 )analysis by ELISA, and for β2-microglobulin (β2-MG)analysis by ELISA.Kidneys were obtained for histological exa mination after HE stains.RESULTS Positive protein(3 +)was noted for several fe male animals treated for 7 or 14 d at 80 mg·kg -1 and the tendency of recovery were noted at the end of recovery period.Co mpared with those in saline control group treated for 7 d,the seru m BUN and CRE levels for fe males and the CRE level for males were significantly increased at 80 mg·kg -1 (P <0.05),and the BUN level showed the tendency of increase for males at 80 mg·kg -1 (P >0.05).When treated for 14 d,the seru m BUN and CRE levels for fe males and males at 80 mg·kg -1 and the seru m CRE level for fe males at 20 mg·kg -1 were significantly increased when compared with those in saline control group(P <0.05). The seru m BUN and CRE recovered to base line for all animals treated for 14 d followed by a 28 d recov-ery period.Histopathological observation of kidney tissues indicated that focal tubule dilatation was noted for animals treated for 3 d at 20 and 80 mg·kg -1 ,infla mmatory cell infiltration and focal tubule dilatation were noted at 20 mg·kg -1 and focal renal tubular epithelial cell degeneration,infla mmatory cell infiltra-tion,focal casts (lightly)were noted at 80 mg·kg -1 for animals treated for 7 or 14 d.For animals treated for 14 d followed by a 28 d recovery period,only basophilic tubules and renal casts were noted at 80 mg·kg -1 .New urine bio markers determination indicated that KIM-1 level was significantly increased at 20 and 80 mg·kg -1 for animals treated for 3,7 or 14 d when compared with that in saline control group (P<0.05).For animals treated for 14 d followed by a 28 d recovery period,the KIM-1 level was still significantly higher than saline control group for males and fe males at 80 mg·kg -1 and males at 20 mg·kg -1 (P <0.05 ),but there was evidence for reversal.The β2-MG level was significantly increased at 80 mg·kg -1 for animals treated for 3 d(P<0.05),at 20 or 80 mg·kg -1 for animals treated for 7 or 14 d(P<0.05 or P<0.01 ),when compared with that in the saline control group.For animals treated for 14 d followed by a 28 d recovery period,the β2-MG level was still significantly higher than saline control group for males and fe males at 80 mg·kg -1 and fe males at 20 mg·kg -1 (P <0.05),but there was also evidence for reversal.CONCLUSION Urine KIM-1 and β2-GM are more sensitive and specific markers for early diagnosis of kidney injury induced by GM when compared with the traditional approaches to monitor nephrotoxicity.

Objective To evaluate and compare the presence of the nerve root sedimentation sign in patients with lumbar spondylolisthesis (LS) and lumbar disc herniation(LDH). Methods One hundred and fifty-one patients with degen?erative lumbar spinal disease treated by surgery from July 2012 to March 2014 were reviewed retrospectively in Tianjin Hos?pital. All the patients were divided into two groups:LS group (48 cases) and LDH group (103 cases). The clinical outcomes were evaluated by Japanese Orthopedic Association (JOA). The probability of positive sedimentation sign was compared be?tween LS group and LDH group. Correlation between the JOA score and nerve root sedimentation sign were analysed in two groups. Results There was no statistical difference in JOA score between LS group and LDH group (15.83±3.57 vs 16.76± 3.10, t=1.624, P=0.107). A positive sedimentation sign was identified in 39 patients in the LS group (81.25%) but in 65 pa?tients in the LDH group (63.11%). The difference between LS group and LDH group was statistically significant(χ2=5.028, P=0.031). In LS group, JOA scores of patients with positive nerve root sedimentation sign were lower than those of patients with negative nerve root sedimentation sign(15.33±3.50 vs 18.00±3.20, t=2.092,P=0.042);but in LDH group, there was no statistical difference in JOA scores of patients between positive nerve root sedimentation sign and negative nerve root sedi?mentation sign (16.40±3.13 vs 17.37±2.99, t=1.539, P=0.127). Conclusion A positive sedimentation sign also occurs in pa?tients with LDH, but positive nerve root sedimentation sign are more likely to appear in patients with lumbar spondylolisthe?sis who have worse clinical symptoms.

Objective To explore the liver toxicities of the VDLD scheme in children with malignant tumor.Methods In a prospective trial,the levels of serum total protein,albumin, globulin,rate of albumin/globuin alanine aminotransferase,aspartate transaminase,gamma glutamyltranspeptidase,total bile acid and alkaline phosphatase were tested in children with malignant tumour before and after VDLD scheme,and compared with each other.Results The concentration of the serum total bile acid was significantly increased after VDLD scheme than before(P

ObjectiveTo investigate the proliferation of rat's osteoblasts promoted by mechanical strain via the protein kinases C ξ(PKCξ) protein path-way.MethodsOsteoblasts were retrieved from SD rats' skulls in the sterilized environment.BioDynamic testing instrument was used to exert 2％ and 0％ mechanical strain on rats' osteoblasts for 180 min on the each group(2％ mechanical strain was experimental group and 0％ mechanical strain was control group); and the same method was applied on the rats' osteoblasts which pretreated with the classical PKC ξ inhibitor with 2％ mechanical strain (inhibitor group).The cell cycles of rats' osteoblasts were measured by flow cytometry; and Western blotting and immunofluorescence were used to detect expression of protein PKC ξ and phosphorylationed PKC ξ in the rats' osteoblasts.ResultsThe mechanical strain obviously increased the ratio of S period in the cell cycles.Compared to the control group and inhibitor group,a significant increase of the expression of protein PKC ξ and phosphorylationed PKC ξ in the osteoblasts was detected in the mechanical strain experimental group.ConclusionPKCξ can respond to the stimulus of the mechanical strain,which promotes the proliferation of osteoblasts through PKCξ pathway.And it plays an important role in the process of signal conduction.

ObjectiveTo measure the displacement parameters of the femoral head in space through CT three-dimensional reconstruction so as to re-understand impacted femoral neck fractures.MethodsFifty patients with impacted femoral neck fractures were included in the study.There were 17 males and 33 females.Bilateral proximal femurs of each patient were scanned by spiral CT preoperatively.Then these primitive CT data were reconstructed by Mimics 10.01 software.Registered the normal femur and fracture mirror model,the registered mirror model was generated a new mask in the CT cross-sectional images,marked key points in the masks and measured the displacement parameters of femoral head with three-dimensional measurement technology.ResultsIn the impacted femoral neck fractures,the femoral head displacement angle was 17.17°±10.40°,70％(35/50) of the patients had femoral head rotation angle was at 10° to 35°,and 30％(15/50) of the patients had femoral head space displacement more than 20°.The average displacement distance of femoral head center and the deepest point of fovea capitis were(6.49±3.60) mm and(10.42±5.92) mm,respectively.A high proportion of the impacted femoral neck fractures had a large of displacement in the three-dimensional space.It is not scientific to equal impacted femoral neck fractures to undisplaced fractures.ConclusionThree-dimensional reconstruction and digital measurement is a precise,efficient and convenient method for the measurement of femoral head displacement parameters in femoral neck fracture patients.The classic Garden classification for impacted femoral neck fractures has certain defects and limitations.Clinicians should re-understand impacted femoral neck fractures and choose more reasonable treatment.

Objective To build a three-dimension finite-element model of patella and to make a preliminary mechanics analysis on the model.Methods According to the model-building principle of Ansys software which started from point to line to area to volume,a three-dimension finite-element patella model was reconstructed on the basis of the images of spiral CT.Then,loading on the model patella were simulated and the stress magnitude and distribution on the patella were analyzed.Results Finite element analysis of the patella showed that stress concentration zone located in the middle and lower patella,indicating that fracturepredilectionsitesinthelower patellar.TheVon misesstresson thetensionsidewas significantly greater than that on pressure side.Conclusion The established finite element model of the patella can reflect the real geometry of patella treated in clinics.

Objective To evaluate the efficacy of self-retaining suture (QuillTM SRS) in retroperitoneal laparoscopic partial nephrectomy for complicated renal tumor by assessing perioperative parameters.Methods Between 2010 and 2012,78 cases of complicated renal tumor (R.E.N.A.L score ≥ 7) treated by retroperitoneal laparoscopic partial nephrectomy (LPN) with two layers continuous knotless barbed suture (QuillTM SRS group) (n=30) or traditional absorbable vicyl suture (non-SRS group) (n=48) were retrospectively analyzed.In QuillTM SRS group,2-0 Quill SRS was used to suture the deep wound bed,and the second outcr layer renorrhaphy was performed with a 1-0 Quill SRS by the same way.In non-SRS group,the inner layer was sutured using a 15cm in length 2-0 monicryl suture by the same method mentioned above.A second outer layer was sutured with 1-0 vicryl suture across the wound.Cases were matched for R.E.N.A.L score.Comparison was made in term of operation time,preoperative parameter and perioperative complications between SRS group and non-SRS group.Results Renorrhaphy was successfully performed in all cases except 1 case converting to open surgery in non-SRS group.Mean warm ischemia time in SRS group was shorter than non-SRS group (18 vs 25 min,P =0.021).The proportion of bleeding requiring intervention in the non-SRS group (7/48,14.5％) was 4.3-fold higher than that of the SRS group (1/30,3.3％),but the differernce is not significant (P＞0.05).There were no significant differences between two groups in postoperative creatinine changes.Limitations of this study include the absence of randomization and the relative small sample size.Conclusions SRS can be safely used for complicated renal tumor during LPN,and SRS can significantly reduce the WIT and may also reduce bleeding during the operation.

Objective To investigate calcium-sensing receptor (CaSR) expression level in osteoarthritis (OA) carti-lage,and the relationship with OA pathogenesis thereof. Methods The degenerated human cartilage of distal femur and proximal tibia came from 5 patients with OA underwent total knee replacement surgery. The tissue specimens were stained by HE. According to the Collins histological grading standards, articular cartilage degeneration was classificated in speci-mens. Eight HE slices of Collins grade 0 were used as normal cartilage group. Eight HE slices of Collins gradeⅡwere used as degeneration cartilage group. The CaSR expression levels detected by immunohistochemical staining technique were com-pared between two groups. Results Expression of CaSR was detected in osteoarthritis cartilage. The expression intensity of CaSR was significantly lower in normal cartilage group than that of degeneration of cartilage group (score:1.63±0.95 vs 3.52± 0.78,t=8.99,P<0.05). Conclusion The activation of CaSR is associated with the degeneration of articular cartilage.