The Clinical Results And Animal Experimental Study Of The Influence Of Removing The Internal Fixations On The Blood Circulation Of Femoral Head In Femoral Neck Fractures

[Objective]The femoral neck fractures are frequent injuries in orthopaedics. The treatments of the femoral neck fractures are difficult because of nonunion and femoral head necrosis. We find that part of the cases had suffered from femoral head necrosis with removing internal fixations after fracture healing in clinic, and the probability enormously descended if the internal fixations kept in body for long time. The mechanism is unknown. The internal fixations of titanium alloy can keep in body for long time because of its excellent biological compatibility. If some evidences of removing internal fixations make sure adverse effects on blood circulation, or induced the femoral head necrosis, we should select better biological compatible materials keep in body for a long time to avoid potential danger of femoral head necrosis in clinic. [Methods]1, To summarize 157 clinical cases of femoral neck fractures, we analyzed the percents and influencing factors of femoral head necrosis and discussed the relation between removing internal fixations and femoral head necrosis.2 To build animal models of fracture healing after internal fixation of femoral neck fractures. Firstly, two hips make femoral necks fractures, and both fixated with a titanium alloy screw, then the internal fixations are removed after fractures healing. 18 adult healthy crossbreed dogs divided 3 groups by randomization according to 0 months, 2 months and 4 months after removing internal fixations (6 dogs every group).SN To observe the changes of the blood circulation and biomechanical capability of femoral head in the differ period after removing internal fixations using image analyses of X-ray, pathologic histology, SPECT and biomechanical methods. [Results]1 With the analysis of clinical case results, it is greatly correlation between femoral head necrosis and removing internal fixation.2 The femoral neck fractures of the dogs generally united after 3 months with internal fixation.3 The isotopic total count and average count of the region of interest by SPECT is not statistically different before removing internal fixation and the moment of removing internal fixation and 2 months after removing internal fixation.4 With 4 months after removing internal fixations, the isotopic total count and average count of the region of interest by SPECT is remarkably different in statistics and the lift count is more than the right' .There were significantly differences in both failure load and stiffness of the lift and right in statistics.5 With 4 months after removing internal fixations, the femoral heads of right were ischemic by pathologic histology.[Conclusion]1. The animal model of femoral neck fractures is reasonable by fixation with titanium alloy screws. It is more approximate to clinic.2 There were adverse effects on blood circulation in femoral head as a result of removing internal fixation in the base of the animal experiments. The femoral heads of right were ischemic by pathologic histology, the decrease of the isotopic total count and average count of the region of interest by SPECT in 4 months after removing internal fixations is a gradual process. The load ability of the femoral head is not significantly change. They were consistent with the clinical results.3 The titanium alloy screws are recommended to the treatment of femoral neck fractures because of firm fixated, high rate of fracture healing and excellent biological compatibility, and can keep in body for long time. It avoided potential dangers of femoral head necrosis.4 The study only describes the ischemical trend of femoral head after removing internal fixations owing to shorter observed time. It is possible to obtain femoral head necrosis.