Appropriate fluoroscopic angle intraoperation of C-arm X-ray for each curved surface of femoral neck wall: a cadaveric study

Abstract

Objective To detect the appropriate fluoroscopic angle of intraoperative C-arm X-ray based on precise femoral neck anatomy. Methods The femoral neck was divided into the anterior, posterosuperior and posteroinferior surfaces. These surfaces and the coronal plane of the femur formed anterior surface coronal angle (ACA), posterosuperior surface coronal angle (PSCA) and posteroinferior surface coronal angle (PICA), respectively. The three angles of 32 dried femoral specimens were measured. The femoral neck wall attached with steel wire wind aluminum foil model and three Kirschner wires perforating femoral neck wall model were prepared. The C-arm was rotated every 5° to complete the 0° -180 ° fluoroscopy of each curved surface. 111 frames of images were obtained for each femoral specimen. The appropriate fluoroscopic angle of each surface was obtained, and the fluoroscopic images characteristics of Kirschner wire penetrating the femoral neck cortex on three appropriate fluoroscopic angles and the anteroposterior and lateral fluoroscopy were observed. Results The femoral neck is irregularly cylindrical with the anterior surface is longer than the posteroinferior surface, and the posterosuperior surface is the shortest. The measurement data of ACA, PSCA and PICA were (31±4.589)°, (67.813±5.052)° and (168.688±3.206)°, respectively. The appropriate fluoroscopic angle of the anterior, posterosuperior and posteroinferior surface of the steel wire aluminum foil model were (30.781±5.464)°, (67.969±3.721)°, (167.813±4.319)°, respectively. And there was no significant difference with the measurement data of the corresponding surface coronal angles, P > 0.05. The model of wire penetrating the femoral neck wall showed that the Kirschner wire penetrating the femoral neck could not be fully exposed in the traditional anteroposterior and lateral view films. Increasing the appropriate fluoroscopic angle of 30°, 70° and 170° could clearly find the Kirschner wire penetrating the cortex. Conclusion Traditional anteroposterior and lateral fluoroscopy cannot accurately show the true structure of femoral neck. Additional 30°, 70° and 170° fluoroscopy can accurately observe the fracture reduction quality of the anterior surface, posterosuperior surface and posteroinferior surface of the femoral neck and the damage to the corresponding cortical bone caused by internal fixation. Level of evidence: level II