ABSTRACT
BACKGROUND:Finite element method is widely used in the femoral neck fracture, but the study concerning different fixation methods of femoral neck fracture is not much. OBJECTIVE:To analyze biomechanical properties of different fixation methods for femoral neck fracture using finite element analysis. METHODS:The femur of voluntters was scanned with CT, at thickness 0.6 mm, from the site above the greater trochanter of the femur. Scanning data were saved in .DICOM format. Data of right proximal femur were imported into Mimics software. Osteotomy was performed according to Pauwels I type fracture. Models of two tensile force screws, ful y threaded hol ow screw and proximal femoral locking plate were established. Three-dimensional finite element method was used to analyze stress distribution, stress concentration position, displacement distribution and maximum displacement in different models of femoral neck fracture with different internal fixation methods. RESULTS AND CONCLUSION:(1) The maximum stress value of two lag screws model was biggest. The maximum stress value of ful y threaded hol ow screw model was minimized. The maximum stresses of two lag screws model, ful y threaded hol ow screw model and proximal femoral locking plate model al were concentrated in the fixed end of fractures. (2) The femoral maximum stress of two lag screws model was biggest. The femoral maximum stress value of proximal femoral locking plate model was minimized. The femoral maximum stresses of two lag screws model, ful y threaded hol ow screw model and proximal femoral locking plate model al were concentrated in the medial femoral smal rotor near and medial femoral and fixation contact points. (3) The maximum displacement of two lag screws model was biggest. The maximum displacement of ful y threaded hol ow screw model was minimized. The maximum displacement of two lag screws model, ful y threaded hol ow screw model and proximal femoral locking plate model al was in the femoral head. (4) The maximum displacement value of two lag screws model fixed place was biggest. The maximum displacement value of ful y threaded hol ow screw model fixed place was minimized. The maximum displacement value of two lag screws model was biggest at femoral head. The maximum displacement value of ful y threaded hol ow screw model was minimized at femoral head. (5) Results showed that the treatment effect of ful y threaded hol ow screw on Pauwels I fractures was better than other two fixation methods.
ABSTRACT
Objective To explore the effects of melatonin (MT) on the expression of interleukin (IL)-10,interleukin-6 and interleukin-8 as well as the inflammatory reaction and nerve repair after acute spinal cord injury (SCI).Methods One hundred and eight Sprague-Dawley rats were randomly divided into a spinal cord injury group (group A),an MT treatment group (group B) and a sham operation group (group C),each with 36 rats.SCI models were established in the rats of groups A and B using a version of Allen's weight drop method (50gcf at the T12 level).Group C had removal of the lamina only.Ten minutes later,group A was injected with 5％ ethanol in saline (the MT solvent) and group B with 100 mg/kg of melatonin preparation.At 6,12,18 and 24 hours,IL-6,IL-8 and IL-10 levels in serum were detected in 6 rats of each group.At 18 hours post-surgery,spinal cord specimens were taken from 6 rats of each group for hematoxylin eosin staining,morphological examination and immunohistochemical SP detection of IL-10 expression.Results The specimens of group A showed inflammatory reaction and ulceration at 48 h; groups B and C had no ulcers.Group B showed the highest levels of IL-10 in serum and IL-10 mRNA in the spinal cord,while group C showed the lowest level.The differences were statistically significant.Group A had the highest levels of IL-6 and IL-8 and group C had the lowest.The difference between group B and groups A and C was significant.The morpho-logical observation showed that after melatonin treatment the IL-10 levels in the spinal cord's central canal and around the gray matter improved.Conclusions Melatonin can improve nerve lipid peroxidation and inflammatory reaction in the treatment of spinal cord injury by increasing IL-10 expression and inhibiting IL-6 and IL-8 expression.