Proper alignment of acetabular implantation is necessary for good patient outcomes and preventing complications or additional surgeries in total hip arthroplasty (THA). Rotation of the pelvis in lateral decubitus (LD) is typically not accounted for as surgeons use the surgery table as a reference plane to align implants. This study compared four techniques to measure 3D pelvic rotations in LD position using computer models. CT scans of 19 subjects in LD position were used to create 3D pelvis models. Pelvic rotations were measured by three users using four techniques: landmark (LM), defined plane (DP), anterior pelvic plane (APP), and plane of best symmetry (POBS) methods. Measurements were analysed for intra-user reliability and relationships between methods were assessed using intraclass correlation coefficient, standard error of measurement, and coefficient of determination. The POBS method exhibited the highest inter-observer reliability and is recommended as a new measurement technique to measure pelvic rotations before THA surgery. The LM method exhibited low reliability but may be suitable for expert users familiar with pelvic landmarks. The APP method should only be used when the patients’ APP planes are known in neutral standing and side-lying postures. The DP method is not recommended due to substantial individual variability.

Graphical abstract

髋臼植入物的正确对准对于获得良好的患者结果，防止并发症或全髋关节置换术（THA）的额外手术是必要的。由于外科医生使用手术台作为对齐植入物的参考平面，因此通常不考虑外侧卧位（LD）的骨盆旋转。这项研究比较了使用计算机模型测量LD位置中3D骨盆旋转的四种技术。LD位置的19位受试者的CT扫描用于创建3D骨盆模型。三个使用者使用四种技术测量骨盆旋转：界标（LM），定义平面（DP），骨盆前平面（APP）和最佳对称平面（POBS）方法。分析了用户内部可靠性的度量，并使用类内相关系数，度量标准误差，和确定系数。POBS方法表现出最高的观察者间可靠性，被推荐作为THA手术前测量骨盆旋转的新测量技术。LM方法显示出较低的可靠性，但可能适合熟悉骨盆界标的专业用户。仅当以中立站立和侧卧姿势知道患者的APP平面时，才应使用APP方法。由于个体差异很大，不建议使用DP方法。仅当以中立站立和侧卧姿势知道患者的APP平面时，才应使用APP方法。由于个体差异很大，不建议使用DP方法。仅当以中立站立和侧卧姿势知道患者的APP平面时，才应使用APP方法。由于个体差异很大，不建议使用DP方法。

图形概要