Abstract：
OBJECTIVE: The femoral anteversion angle is considered to be the same as femoral torsion; however, the femoral anteversion angle is strongly influenced by the femoral posterior condylar morphology. It remains unclear whether the femoral anteversion angle and axial orientation of the femoral trochlea can predict patellar instability. This study aimed to redefine the femoral inherent torsion, verify whether the femoral anteversion angle reflects the femoral inherent torsion, and compare the validity and calculate the cut-off values of the femoral anteversion angle and femoral trochlear axial orientation for predicting patellar instability.
METHODS: Seventy-three patients with patellar instability and 73 matched controls underwent computed tomography to measure the femoral anteversion angle, femoral inherent torsion, and femoral trochlear axial orientation. Pearson\'s product moment correlation coefficients and linear regression were calculated to determine correlations between measurements. Receiver operating characteristic curves and nomograms were plotted to evaluate the predictive validity of the femoral anteversion angle and femoral trochlear axial orientation for patellar instability.
RESULTS: All measurements showed excellent intra- and inter-observer reliability. Compared with the control group, the patellar instability group had a significantly larger femoral anteversion angle (25.4 ± 6.4° vs. 20.2 ± 4.5°) and femoral inherent torsion (18.3 ± 6.7° vs. 15.8 ± 3.4°), and significantly smaller femoral trochlear axial orientation (58.1 ± 7.3° vs. 66.9 ± 5.1°). The femoral anteversion angle and femoral trochlear axial orientation had area under the receiver operating characteristic curve values of 79 and 84%, respectively, and cut-off values of 24.5° and 62.7°, respectively. The calibration curve and decision curve analysis showed that the femoral trochlear axial orientation performed better than the femoral anteversion angle in predicting patellar instability. There was a strong correlation between the femoral anteversion angle and femoral inherent torsion (r > 0.8). Linear regression analysis of the femoral inherent torsion with the femoral anteversion angle as the prediction variate showed moderate goodness-of-fit (adjusted R2 = 0.69).
CONCLUSIONS: The femoral anteversion angle moderately reflects the femoral inherent torsion. The femoral trochlear axial orientation is better than the femoral anteversion in predicting patellar instability in terms of predictive efficiency, consistency with reality, and net clinical benefit. These findings warn orthopaedists against overstating the role of the femoral anteversion angle in patellar instability, and suggest that the femoral trochlear axial orientation could aid in identifying at-risk patients and developing surgical strategies for patellar instability.
METHODS: III.
METHODS: Seventy-three patients with patellar instability and 73 matched controls underwent computed tomography to measure the femoral anteversion angle, femoral inherent torsion, and femoral trochlear axial orientation. Pearson\'s product moment correlation coefficients and linear regression were calculated to determine correlations between measurements. Receiver operating characteristic curves and nomograms were plotted to evaluate the predictive validity of the femoral anteversion angle and femoral trochlear axial orientation for patellar instability.
RESULTS: All measurements showed excellent intra- and inter-observer reliability. Compared with the control group, the patellar instability group had a significantly larger femoral anteversion angle (25.4 ± 6.4° vs. 20.2 ± 4.5°) and femoral inherent torsion (18.3 ± 6.7° vs. 15.8 ± 3.4°), and significantly smaller femoral trochlear axial orientation (58.1 ± 7.3° vs. 66.9 ± 5.1°). The femoral anteversion angle and femoral trochlear axial orientation had area under the receiver operating characteristic curve values of 79 and 84%, respectively, and cut-off values of 24.5° and 62.7°, respectively. The calibration curve and decision curve analysis showed that the femoral trochlear axial orientation performed better than the femoral anteversion angle in predicting patellar instability. There was a strong correlation between the femoral anteversion angle and femoral inherent torsion (r > 0.8). Linear regression analysis of the femoral inherent torsion with the femoral anteversion angle as the prediction variate showed moderate goodness-of-fit (adjusted R2 = 0.69).
CONCLUSIONS: The femoral anteversion angle moderately reflects the femoral inherent torsion. The femoral trochlear axial orientation is better than the femoral anteversion in predicting patellar instability in terms of predictive efficiency, consistency with reality, and net clinical benefit. These findings warn orthopaedists against overstating the role of the femoral anteversion angle in patellar instability, and suggest that the femoral trochlear axial orientation could aid in identifying at-risk patients and developing surgical strategies for patellar instability.
METHODS: III.
摘要：
目的：股骨前倾角被认为与股骨扭转相同；但是，股骨前倾角受股骨后髁形态的强烈影响。目前尚不清楚股骨前倾角和股骨滑车的轴向方向是否可以预测髌骨不稳定。这项研究旨在重新定义股骨固有扭转，验证股骨前倾角是否反映股骨固有扭转，比较股骨前倾角和股骨滑车轴向方向预测髌骨不稳定的有效性并计算其临界值。
方法：73名髌骨不稳定患者和73名匹配的对照者接受了计算机断层扫描以测量股骨前倾角，股骨固有扭转，和股骨滑车轴向取向。计算皮尔逊积矩相关系数和线性回归以确定测量值之间的相关性。绘制了接收器工作特征曲线和列线图，以评估股骨前倾角和股骨滑车轴向方向对the骨不稳定性的预测有效性。
结果：所有测量均显示出出色的观察者内部和观察者之间的可靠性。与对照组相比,髌骨不稳定组股前倾角明显较大(25.4±6.4°vs.20.2±4.5°)和股骨固有扭转(18.3±6.7°vs.15.8±3.4°),和明显较小的股骨滑车轴向方向（58.1±7.3°vs.66.9±5.1°)。股骨前倾角和股骨滑车轴向方向的接收器工作特性曲线下面积值为79％和84％，分别,截止值分别为24.5°和62.7°，分别。校准曲线和决策曲线分析表明，股骨滑车轴向定位在预测髌骨不稳定方面优于股骨前倾角。股骨前倾角与股骨固有扭转之间存在很强的相关性（r>0.8）。以股骨前倾角为预测变量的股骨固有扭转的线性回归分析显示出中等的拟合优度（调整后的R2=0.69）。
结论：股骨前倾角适度地反映了股骨固有扭转。股骨滑车轴向定位在预测髌骨不稳定的预测效率方面优于股骨前倾,与现实的一致性,和净临床效益。这些发现警告骨科医师不要夸大股骨前倾角在髌骨不稳定中的作用，并提示股骨滑车轴向定位有助于识别高危患者和制定髌骨不稳定的手术策略。
方法：III.
方法：73名髌骨不稳定患者和73名匹配的对照者接受了计算机断层扫描以测量股骨前倾角，股骨固有扭转，和股骨滑车轴向取向。计算皮尔逊积矩相关系数和线性回归以确定测量值之间的相关性。绘制了接收器工作特征曲线和列线图，以评估股骨前倾角和股骨滑车轴向方向对the骨不稳定性的预测有效性。
结果：所有测量均显示出出色的观察者内部和观察者之间的可靠性。与对照组相比,髌骨不稳定组股前倾角明显较大(25.4±6.4°vs.20.2±4.5°)和股骨固有扭转(18.3±6.7°vs.15.8±3.4°),和明显较小的股骨滑车轴向方向（58.1±7.3°vs.66.9±5.1°)。股骨前倾角和股骨滑车轴向方向的接收器工作特性曲线下面积值为79％和84％，分别,截止值分别为24.5°和62.7°，分别。校准曲线和决策曲线分析表明，股骨滑车轴向定位在预测髌骨不稳定方面优于股骨前倾角。股骨前倾角与股骨固有扭转之间存在很强的相关性（r>0.8）。以股骨前倾角为预测变量的股骨固有扭转的线性回归分析显示出中等的拟合优度（调整后的R2=0.69）。
结论：股骨前倾角适度地反映了股骨固有扭转。股骨滑车轴向定位在预测髌骨不稳定的预测效率方面优于股骨前倾,与现实的一致性,和净临床效益。这些发现警告骨科医师不要夸大股骨前倾角在髌骨不稳定中的作用，并提示股骨滑车轴向定位有助于识别高危患者和制定髌骨不稳定的手术策略。
方法：III.
