Yamada Yuzo, Toritsuka Yukiyoshi, Nakamura Norimasa, Horibe Shuji, Sugamoto Kazuomi, Yoshikawa Hideki, Shino Konsei
Department of Orthopaedic Surgery, Japan Community Healthcare Organization, Osaka Hospital, Osaka, Japan.
Department of Orthopaedic Sports Medicine, Kansai Rosai Hospital, Amagasaki, Japan.
Am J Sports Med. 2017 Nov;45(13):3111-3118. doi: 10.1177/0363546517720193. Epub 2017 Aug 22.
The concepts of lateral deviation and lateral inclination of the patella, characterized as shift and tilt, have been applied in combination to evaluate patellar malalignment in patients with patellar dislocation. It is not reasonable, however, to describe the 3-dimensional (3D) positional relation between the patella and the femur according to measurements made on 2-dimensional (2D) images.
The current study sought to clarify the relation between lateral deviation and inclination of the patella in patients with recurrent dislocation of the patella (RDP) by redefining them via 3D computer models as 3D shift and 3D tilt.
Descriptive laboratory study.
Altogether, 60 knees from 56 patients with RDP and 15 knees from 10 healthy volunteers were evaluated. 3D shift and tilt of the patella were analyzed with 3D computer models created by magnetic resonance imaging scans obtained at 10° intervals of knee flexion (0°-50°). 3D shift was defined as the spatial distance between the patellar reference point and the midsagittal plane of the femur; it is expressed as a percentage of the interepicondylar width. 3D tilt was defined as the spatial angle between the patellar reference plane and the transepicondylar axis. Correlations between the 2 parameters were assessed with the Pearson correlation coefficient.
The patients' mean Pearson correlation coefficient was 0.895 ± 0.186 (range, -0.073 to 0.997; median, 0.965). In all, 56 knees (93%) had coefficients >0.7 (strong correlation); 1 knee (2%), >0.4 (moderate correlation); 2 knees (3%), >0.2 (weak correlation); and 1 knee (2%), <0.2 (no correlation). The mean correlation coefficient of the healthy volunteers was 0.645 ± 0.448 (range, -0.445 to 0.982; median, 0.834). A statistically significant difference was found in the distribution of the correlation coefficients between the patients and the healthy volunteers ( P = .0034). When distribution of the correlation coefficients obtained by the 3D analyses was compared with that by the 2D (conventional) analyses, based on the bisect offset index and patellar tilt angle, the 3D analyses showed statistically higher correlations between the lateral deviation and inclination of the patella ( P < .01).
3D shift and 3D tilt of the patella were moderately or strongly correlated in 95% of patients with RDP at 0° to 50° of knee flexion.
It is not always necessary to use both parameters when evaluating patellar alignment, at least for knees with RDP at 0° to 50° of flexion. Such a description may enable surgeons to describe patellar alignment more simply, leading to a better, easier understanding of the characteristics of each patient with RDP.
髌骨的外侧移位和外侧倾斜概念，分别表现为移位和倾斜，已被联合应用于评估髌骨脱位患者的髌骨排列不齐情况。然而，根据二维（2D）图像测量结果来描述髌骨与股骨之间的三维（3D）位置关系并不合理。
本研究旨在通过三维计算机模型将复发性髌骨脱位（RDP）患者的髌骨外侧移位和倾斜重新定义为三维移位和三维倾斜，以阐明二者之间的关系。
描述性实验室研究。
共评估了56例RDP患者的60个膝关节以及10名健康志愿者的15个膝关节。通过磁共振成像扫描创建三维计算机模型，以10°的膝关节屈曲间隔（0° - 50°）分析髌骨的三维移位和倾斜。三维移位定义为髌骨参考点与股骨髓中线平面之间的空间距离；以髁间宽度的百分比表示。三维倾斜定义为髌骨参考平面与经髁轴之间的空间角度。使用Pearson相关系数评估这两个参数之间的相关性。
患者的平均Pearson相关系数为0.895±0.186（范围，-0.073至0.997；中位数，0.965）。总体而言，56个膝关节（93%）的系数>0.7（强相关）；1个膝关节（2%），>0.4（中度相关）；2个膝关节（3%），>0.2（弱相关）；1个膝关节（2%），<0.2（无相关）。健康志愿者的平均相关系数为0.645± 0.448（范围，-0.445至0.982；中位数，0.834）。患者与健康志愿者之间的相关系数分布存在统计学显著差异（P = 0.0034）。当将三维分析获得的相关系数分布与基于平分偏移指数和髌骨倾斜角的二维（传统）分析结果进行比较时，三维分析显示髌骨外侧移位与倾斜之间的相关性在统计学上更高（P < 0.01）。
在膝关节屈曲0°至50°时，95%的RDP患者中髌骨的三维移位和三维倾斜呈中度或强相关。
在评估髌骨排列时，至少对于膝关节屈曲0°至50°的RDP患者，并非总是需要同时使用这两个参数。这样的描述可能使外科医生能够更简单地描述髌骨排列，从而更好、更轻松地理解每位RDP患者的特征。
