The Femoro-Epiphyseal Acetabular Roof (FEAR) index is a newer measurement to identify the hip instability with borderline acetabular dysplasia. The purpose of this study is to (i) validate the FEAR index in determining the stability of the hip in patients who have previously been treated surgically for femoroacetabular impingement (FAI) and/or developmental dysplasia of the hip (DDH) and (ii) to examine the relationship between the FEAR index and femoral version, lateral center edge angle, Tönnis angle and alpha angle (AA). Patient demographics and radiographic measurements of 215 hips (178 patients), 116 hips treated with hip arthroscopy for FAI and 99 hips treated with periacetabular osteotomy (PAO) for DDH were compared between groups. The sensitivity and specificity of the FEAR index to detect the surgical procedure performed (PAO or hip arthroscopy) was calculated, and a threshold value was proposed. Pearson’s correlation coefficients were used to describe the relationships between the FEAR index, femoral version and other radiographic measurements. The FEAR index was higher in patients with DDH versus FAI (DDH: 2.81 ± 0.50° versus FAI: −1.00 ± 0.21°, P < 0.001). A FEAR index threshold value of 3° had a sensitivity and specificity of 80% and 81%, respectively, for correctly predicting the surgical procedure performed. Femoral version was positively associated with the FEAR index in the setting of DDH (r = 0.36, P = 0.001) but not FAI (r = 0.02, P = 0.807). A FEAR index of 3° predicted treatment with 80% sensitivity and 81% specificity. In addition, femoral version significantly correlates with the FEAR index in the setting of DDH but not FAI.

中文翻译：

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FEAR指数预测股骨髋臼撞击髋关节发育不良患者治疗效果与股骨旋度的关系

Femoro-Epiphyseal 髋臼顶 (FEAR) 指数是一种较新的测量方法，用于识别边缘髋臼发育不良的髋关节不稳定。本研究的目的是 (i) 验证 FEAR 指数在确定先前因股骨髋臼撞击 (FAI) 和/或发育性髋关节发育不良 (DDH) 接受过手术治疗的患者的髋关节稳定性和 (ii)检查 FEAR 指数与股骨版本、外侧中心边缘角、Tönnis 角和 α 角 (AA) 之间的关系。对 215 髋（178 名患者）、116 髋接受髋关节镜检查治疗 FAI 和 99 髋接受髋臼周围截骨术 (PAO) 治疗 DDH 的患者人口统计学和影像学测量结果进行了比较。计算了 FEAR 指数检测所进行的外科手术（PAO 或髋关节镜检查）的敏感性和特异性，并提出了一个阈值。Pearson 相关系数用于描述 FEAR 指数、股骨版本和其他放射学测量值之间的关系。DDH 与 FAI 患者的 FEAR 指数更高（DDH：2.81 ± 0.50° 与 FAI：-1.00 ± 0.21°，P < 0.001）。FEAR 指数阈值 3° 的敏感性和特异性分别为 80% 和 81%，用于正确预测所进行的外科手术。股骨版本与 DDH 设置中的 FEAR 指数呈正相关（r = 0.36，P = 0.001），但与 FAI 无关（r = 0.02，P = 0.807）。3° 的 FEAR 指数预测治疗的敏感性为 80%，特异性为 81%。此外，