| Femoral neck fracture is a common clinical injury, the world has more than 1 million per year from the femoral neck fracture Fractures typing choice has important significance for diagnosis, treatment, and prognosis. The most commonly used method of femoral neck fracture type Garden parting, AO classification, Pauwel type, anatomical type. Different sub-type has its own ideas, and to guide clinical in some degree. But these sub- type are based on X-rays of typing, in fact, it can be manifested as intercalation fractures, internal and external turning, internal and external rotation, shift and other various forms, two-dimensional X-ray does not accurately describe its complexity, based on typing X-rays have certain limitations are inevitable. Some studies have recognized the importance of three-dimensional CT imaging diagnosis and treatment of femoral neck fracture that it can better reflect the fracture morphology, to guide treatment, and may prognosis. Therefore, we hope that the development of femoral neck fracture classification based on CT images, and judge its value in the subsequent working.In the typing process of CT imaging of the femoral neck fracture, we get some interes of femoral neck fracture withe bone defects. Anatomic femoral neck fracture importance of doubt. Reset standards such as Garden index main consideration is the fracture of the line, without requirements of the fracture intercalation However, for reset Garden index is good, but the fracture intercalation, shortening the femoral neck fracture can be called anatomic it? Such fractures should be merged bone loss, namely bone defect. So we use CT imaging, bone defects of femoral neck fracture occurred were evaluated. After the assessment, we use body bone, produced a model of the femoral neck bone defects, and using a resistance strain gauge measuring method, the various types of defects in the biomechanical properties were tested to evaluate various types of bone defect of the proximal femur the biomechanical properties of.The first part The analysis of CT image for femoral neck fracture with 150 casesObjective Under the premise of the pursuit of the ideal anatomical reduction, assess the bone defects of femoral neck fracture with CT imaging.Methods 2009-2011.12, do spiral CT scan to 150 cases of femoral neck fractures in our hospital, in which eliminate the old fractures, pathological fractures, and the cases of ipsilateral acetabular fractures. The spiral CT and 3D reconstruction images of lmm were scanned in all cases. Classify the femoral neck fracture with CT imaging, put forward the concept of potential bone defects and true bone defect, and count the occurred parts and the degree of various types of bone defects.According to the CT image, the data of this group was classified by Graden classification standard, and the number of cases was statistically analyzed. The following 6 cases are considered as "tential bone defects":1. Femoral neck fracture, the femoral neck is embedded in the evaginable femoral head. Or pursue anatomical reduction, in the correction of the evaginable femoral head, bone defect occurred above the femoral neck.2. In the fracture, the proximal cortical bone is embedded in the cancellous bone and the bone defect of the femoral neck is present.3. Fractures of the proximal adductor shift, without rotation, fracture is mutual intercalation, bone loss in the femoral neck below, within the bottom of femoral neck the presence of bone defects after reset.4. Varus and external rotation fracture displacement, fractures of the distal embedded in the proximal rear, the rear side of the femoral neck bone defect exists after reset.5. Varus and external rotation fracture displacement, proximal fractures of the distal embedded in the rear, the rear side of the existence of femoral neck bone defects after reset, more severe fracture intercalation.6. Cut displaced femoral neck fracture at the base, below the femoral neck bone defect exists after reset. With the CT images of the "true bone defect" fracture fragments occurrence site classification, the fracture fragments into "anterior" "internal carotid under" "posterior" "jugular on" "comminuted fracture."Results:In 150 cases of femoral neck fracture, there were 99 cases of potential bone defect, 66.00% of the total cases; Posterior defects were the most common (48 cases,48.5%),26 cases of "true bone defect",17.33% of the total cases, posterior defects were the most common (12 cases,8.00%)Conclusions:Spiral CT images can reflect the form of fractures and bone defects intuitively and three-dimensionally. Femoral neck fracture has a high incidence of potential bone defect, attention should be paid to it.The second part The impact of different types of femoral neck bone defect on the biomechanical properties of the proximal femur.Objective:Evaluating several neck "true bone defects" on the biomechanics of the proximal femur.Methods:Randomly selected three corrosion femur young specimens with same region, ethnicity and gender, using X-ray radiography and eyes to exclude fractures, tumors, tuberculosis and congenital malformations, removal of muscle, soft tissue, joint capsule, ligaments, and then mark the specimen numbers. We tested the femoral neck bone defect model of body bone with mechanical hydraulic servo testing machine. In this study, we are concerned about the occurrence of femoral neck bone defects, the stress of the femoral head if there is a change. Therefore, we chose to test point, most of the testing points were arranged on the surface of the femoral head, the position of the eight test points were as follows:? greater trochanter. ? neck rear. ? the rear side of the femoral head. ? femoral head-neck junction. ? the front side of the femoral head. ? small rotor.? femoral head just above the outer slant; ? medial femoral neck. Pre-test results showed no significant difference in bone mineral density test, eliminate creep force at the same point of view, the test results from different samples were still significant different between the femurs, which might be related to the difference qualities, anatomic morphological and the sizes of the femur bones. In order to eliminate this kind of experimental error, we designed experimental programs:The same femur, in accordance with the aforementioned method after pasting sheet resistance stress test strain value of each piece of stress. All the tests were measured three times, and recorded the average value. Then removed the femur, and produced a bone defect model, we continued to test three times according to the same method, recording the results, and compared the results before and after the defect. The manufacturing method of the true neck bone defect model:(1) medial femoral neck bone defect model:along the long axis of the femoral neck to neck, creating 2cm long, lcm wide rectangular bone defect at the base starting at the inside of the neck. (2) neck above the bone defect model:along the long axis of the femoral neck to neck, creating 2cm long, lcm wide rectangular bone defect at the base starting at the neck side. (3) rear neck bone defect model:along the long axis of the femoral neck, creating 2cm long, 1cm wide rectangular bone defects slightly above the neck.Result:Medial femoral neck. Under 600N case, the increased strain values on number ? to ? of the test points were 25.78%,21.52%,7.30%,29.96%,-18.16%,8.90%, 19.34%. number ? of test points:Femoral head stress to number ? of test points (femoral head just above) the maximum (19.34%). Under 1200N case, the increased strain values on number ? to ? of test points were 24.01%,54.3%,12.83%,29.68%,-16.01%, 15.78%,31.33%. Number ? of test points:Femoral head stress to number ? (femoral head just above) was max. Medial femoral neck. Neck above the bone defect model:600N (haploid weight) case, from 1 to 8 test point strain values were increased 34.30%, 61.69%,-9.01%,5.82%,10.23%-18.94%-4.13%-10.39%. Under 1200N case, the increased strain values on number ? to ? of test points were 31.67%,122.41%,-7.63%,1.51%,14.20%-12.14%,13.02%,13.63%. In number ? of test points (neck rear) the greatest change. Rear neck bone defect model:Under 600N, the first to the 8th test point (no ? number) strain values were increased 30.76%,15.79%,24.87%,45.19%, 58.85%,37.84%,48.60%. Number? of test points:Femoral head stress to number ? (femoral head just above) was max. Strain values 1200N (double weight) number ? ? ? of test points (no number ?) increased 61.07%,10.16%,25.42%,0.20%,34.64%, 50.74%,48.29%, respectively, number ? of test points:Femoral head stress to number ? (femoral head just above) was max.Conclusion:After various types of femoral neck fracture bone defects, the biomechanics of the proximal femoral neck were all changed. In the double weight, posterior cervical bone defect affected the value stress just above the femoral head most, the medial femoral neck bone defect directly affected the above femoral head, while the external carotid above the bone defect less affected the stress of the femoral head. |
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