Objectives: 

To evaluate the interobserver reliability of measured displacement and occult instability of minimally displaced lateral compression type 1 (LC1) fractures on lateral stress radiographs (LSRs) and to compare differences in displacement between LSR with the injured side down (ID) and up (IU).

Design: 

Retrospective review.

Setting: 

Urban Level 1 trauma center.

Patients/Participants: 

Twenty-three adult patients with minimally displaced (<1 cm) LC1 injuries.

Intervention: 

None.

Main Outcome Measurements: 

Three orthopaedic surgeons measured the distance between the radiographic teardrops on LSR and supine anteroposterior pelvic radiographs to calculate dynamic fracture displacement. The interobserver reliability of the measured displacement, a continuous variable, was assessed by calculating the intraclass correlation coefficient. The interobserver reliability of occult instability (≥10 mm of displacement on LSR), a categorical variable, was assessed by calculating the kappa value. Matched-pairs analysis was performed to calculate the mean difference of measurements between observers and between ID and IU LSR.

Results: 

The interobserver reliability of the measured displacement was excellent (intraclass correlation coefficient 0.93). The mean difference in measurements between observers ranged from −1.8 to 0.96 mm. The mean difference in the measured displacement between ID and IU LSRs for each observer ranged from −0.6 to 0.3 mm. There was 83% (19/23 cases) agreement on the presence of occult instability (≥10 mm of displacement on LSR) on both ID and IU LSRs. The interobserver reliability of occult instability was moderate (kappa 0.76).

Conclusions: 

Measured fracture displacement and occult instability of minimally displaced LC1 injuries were reliably measured and identified on LSR, regardless of the laterality.

中文翻译：

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侧向压缩 1 型骨盆损伤的侧向应力射线照片，受伤侧向下或向上，可靠地测量隐匿性不稳定性

目标： 

评估横向应力射线照片 (LSR) 上最小位移横向压缩 1 型 (LC1) 骨折的测量位移和隐匿不稳定性的观察者间可靠性，并比较 LSR 与受伤侧向下(ID) 和向上 (IU)之间的位移差异.

设计： 

回顾性审查。

环境： 

城市一级创伤中心。

患者/参与者： 

23 名轻度移位 (<1 cm) LC1 损伤的成年患者。

干涉： 

没有任何。

主要结果测量： 

三名整形外科医生测量了 LSR 上的放射线泪滴与仰卧位骨盆前后位 X 线片之间的距离，以计算动态骨折位移。测量位移的观察者间可靠性是一个连续变量，通过计算组内相关系数来评估。通过计算 kappa 值评估分类变量隐匿性不稳定性（LSR 位移≥10 mm）的观察者间可靠性。进行配对分析以计算观察者之间以及 ID 和 IU LSR 之间的测量值的平均差异。

结果： 

测量位移的观察者间可靠性非常好（组内相关系数 0.93）。观察者之间测量值的平均差异范围为 -1.8 至 0.96 毫米。每个观察者的 ID 和 IU LSR 之间测量位移的平均差异范围为 -0.6 至 0.3 mm。83%（19/23 例）一致认为 ID 和 IU LSR 都存在隐匿性不稳定（LSR 位移≥10 mm）。神秘不稳定性的观察者间可靠性是中等的 (kappa 0.76)。

结论： 

无论偏侧性如何，都可以在 LSR 上可靠地测量和识别微小移位 LC1 损伤的测量骨折移位和隐匿性不稳定性。