Laboratoire de physiologie de l'exercice, EA 4338, Saint-Etienne, France.
Orthop Traumatol Surg Res. 2009 Feb;95(1):70-6. doi: 10.1016/j.otsr.2008.01.001. Epub 2009 Jan 30.
Sagittal pelvic balance is a recognized factor influencing targeted acetabular-component anteversion during total hip arthroplasty implantation. However, no studies in the literature have systematically reported pelvic parameters data in the standing, sitting and supine positions.
Variations in acetabular cup orientation can be traced to eventual pelvic balance changes in one of these three usual positions.
In these three positions (supine, standing and sitting), pelvic anatomical parameters and reference planes were radiologically defined from a group of 67 patients (average age: 70.2+/-3.2 years). The complete X-rays individual sets were digitized and measurements were obtained by a single operator using a Spineview software (previously, strictly validated for these kind of measurements). Positioning according to the Lewinnek pelvic coordinate system, which is considered as a possible source of errors when vertically standing or horizontally lying, was also investigated.
The average pelvic incidence of 59.6 degrees did not vary in the sitting, supine or standing positions, with no statistically significant difference between sexes. The Legaye equation--pelvic incidence is equals to pelvic version plus sacral slope--was verified. Pelvic version increased by an average 22 degrees from the sitting to the supine or standing positions. Sacral slope varied in a reverse order. Pelvic-femoral angle (PFA) decreased by 20 degrees from the standing to the supine position. The Lewinnek plane was located 4 degrees posterior to the vertical plane. Whatever the position adopted, pelvi-Lewinnek angle appeared constant, averaging 12 degrees.
The average pelvic incidence in this series was high, most probably associated with advancing patient age and/or pathology. The concept of functional anteversion appeared critical when taking into account pelvic version variations (according to the position, sitting, supine or standing) positions. The Lewinnek plane, commonly accepted as the reference plane for hip navigation, was individualised to each patient and should not be mistaken with the vertical plane; positioning of the femur in relation to the Lewinnek plane was also specific to each patient. Cumulative approximation on these two parameters at surgery resulted in a combined imprecision of 26 degrees when standing and 36 degrees when lying down. We have thus defined crucial parameters to be integrated in computer-assisted hip surgery softwares: positional variations of the pelvic version (functional anteversion), positioning of the Lewinnek plane, and PFA value (both specifically patient's dependant). If integration of these parameters into new sofwares versions appears possible, this would represent a reliable compromise between maximum prosthetic stability, maximum joint amplitudes and elimination of possible prosthetic conflict.
矢状骨盆平衡是影响全髋关节置换术中髋臼假体前倾角的公认因素。然而，文献中没有研究系统地报告站立、坐和仰卧位的骨盆参数数据。
在这三个通常的位置中的一个位置中，髋臼杯方位的变化可以追溯到最终的骨盆平衡变化。
在这三个位置（仰卧、站立和坐姿）中，通过对 67 名患者（平均年龄：70.2±3.2 岁）的一组 X 线进行放射学定义了骨盆解剖参数和参考平面。使用 Spineview 软件（之前已严格针对此类测量进行了验证）对个体 X 线片进行数字化并由一名操作人员进行测量。还研究了根据 Lewinnek 骨盆坐标系进行定位的情况，当垂直站立或水平躺卧时，该坐标系被认为是可能产生误差的来源。
59.6 度的平均骨盆入射角在坐姿、仰卧位或站立位时没有变化，性别之间无统计学差异。验证了 Legaye 方程——骨盆入射角等于骨盆版本加骶骨斜率。骨盆版本从坐姿增加到仰卧位或站立位平均增加 22 度。骶骨斜率呈相反顺序变化。骨盆股骨角（PFA）从站立位到仰卧位减少 20 度。Lewinnek 平面位于垂直平面后面 4 度处。无论采用何种体位，骨盆-Lewinnek 角均保持不变，平均为 12 度。
本系列中平均骨盆入射角较高，很可能与患者年龄增长和/或疾病有关。考虑到骨盆版本变化（根据位置、坐姿、仰卧位或站立位）时，功能前倾角的概念显得至关重要。Lewinnek 平面通常被接受为髋关节导航的参考平面，但它是个体化的，不应与垂直平面混淆；股骨相对于 Lewinnek 平面的定位也因患者而异。手术时对这两个参数的累积近似导致站立时的总误差为 26 度，躺下时为 36 度。因此，我们定义了要集成到计算机辅助髋关节手术软件中的关键参数：骨盆版本的位置变化（功能前倾角）、Lewinnek 平面的定位以及 PFA 值（两者均取决于患者）。如果将这些参数集成到新版本的软件中成为可能，这将是在最大假体稳定性、最大关节幅度和消除潜在假体冲突之间的可靠折衷。
