Kay R M, Jaki K A, Skaggs D L
Pediatric Orthopaedics, Children's Hospital Los Angeles, California 90027, USA.
J Pediatr Orthop. 2000 Nov-Dec;20(6):736-9. doi: 10.1097/00004694-200011000-00007.
Femoral neck-shaft angle (NSA) was measured in a series of anteroposterior (AP) hip radiographs of a cadaveric femur in varying degrees of rotation. A mathematical model was developed to predict NSA on an AP radiograph in varying degrees of femoral rotation. The predictions of the model were found to correlate well with the experimental data (correlation coefficient = 0.94). Based on the mathematical model, a wide range of patient positioning was found to result in a <10 degrees error in the measurement of femoral NSA. Coxa vara, increased femoral anteversion, cerebral palsy, and developmental dislocation of the hip resulted in a more restricted range of acceptable femoral positioning. External rotation of the femur should be avoided during patient positioning because as little as 7 degrees can cause a > 10 degrees change in the apparent NSA. For all patient populations, internally rotating the femur will allow for determination of the femoral NSA to within 10 degrees .
在一系列不同旋转角度的尸体股骨前后位（AP）髋关节X线片中测量股骨颈干角（NSA）。建立了一个数学模型来预测不同股骨旋转角度下AP X线片上的NSA。发现该模型的预测结果与实验数据相关性良好（相关系数 = 0.94）。基于该数学模型，发现广泛的患者体位导致股骨NSA测量误差<10度。髋内翻、股骨前倾角增加、脑瘫和发育性髋关节脱位导致可接受的股骨体位范围更受限。患者体位摆放期间应避免股骨外旋，因为仅7度的外旋就可导致表观NSA变化>10度。对于所有患者群体，将股骨内旋可使股骨NSA的测定误差在10度以内。
