The experimental of the optimal angle position of X-ray in the dosed reduction of femoral neck fracture using internal fixation / 中华骨科杂志

ABSTRACT

Objective To find out the display rules of the key part of the proximal femur and fracture line and obtain the best viewing position and angle by placing the femoral neck at different positions and different angles through X-ray.Methods Six dry specimens of cadaveric femur were from Department of Anatomy,Tianjin Medical University.Three models of complete femoral neck model,tin line fracture model and steel saw fracture model were made respectively.The tin line fracture model was based on the Pauwells angle,using the tin wire(1mm) wrapped around the femoral necks to make three kinds of fracture models (Pauwells angle 30°,50° and 70°);steel saw fracture model was made by hacksaw,then reposition in situ,to make three kinds of fracture models same as the tin line fracture model.The projection manner included different positions and different angles,different projection positions includeparallel with the femoral shaft,perpendicular to the femoral shaft,parallel to the femoral neck and perpendicular to the femoral neck;different projection angles includedfrom 40°,30°,20°,15°,10° and 5° in the head side to 5°,10°,15 °,20 °,30 °and 40° in the foot side and vertical angle 0°.For the complete femoral neck model,we observed the imaging characteristics of the key parts of the femoral head and neck (tension trabecular bone and pressure trabecular bone;lesser trochanter;intertrochanteric line;length of neck of femur and femoral head shape),looking for the display rules,and obtained the best viewing position.For tin line fracture model and steel saw fracture model,we tried to find the best display angle and position by the different projection position and angle.Results The results of complete femoral neck modelLesser trochanterin perpendicular to the femoral shaft position showed the best,gradually increased with the foot side deflection;tension trabecular bone and pressure trabecular bonein parallel with the femoral shaft position 10°on the head side;intertrochanteric lineno difference between parallel with the femoral shaft with perpendicular to the femoral shaft;Femoral neck shapedeflect to both sides,head of femur was out of shape.The results of tin line fracture modelthe Pauwells angle 30° model showed the best position in parallel with the femoral shaft position 20° on the head side;the Pauwells angle 50° model showed the best position in parallel with the femoral shaft position 5° on the head side;the Pauwells angle 70° model showed the best position in parallel with the femoral shaft position 10° on the head side.The results of steel saw fracture model were the same with the tin line fracture model.Conclusion There was the best viewing angles and positions for the key anatomy of the proximal femur and different Pauwells angle classification of femoral neck fracture.The image doctor could make more accurate projection,according to the different types of femoral neck fracture.