Faculty of Medicine, Medical Center, Albert-Ludwigs-University of Freiburg, Hugstetter Strasse 55, 79106, Freiburg, Germany.
Medical Image Computing Group, Department of Informatics, University of Bremen, Enrique-Schmidt-Straße 5, 28359, Bremen, Germany.
Knee Surg Sports Traumatol Arthrosc. 2020 Mar;28(3):759-766. doi: 10.1007/s00167-019-05413-6. Epub 2019 May 4.
Accurate femoral tunnel placement is of great importance during medial patellofemoral ligament (MPFL) reconstruction. Purpose of the present study was to investigate the influence of trochlear dysplasia on the accuracy of fluoroscopic guided femoral tunnel placement.
CT-Scans of 30 knees (five with regular shaped trochlea, 10 with a Type A and five each with a Type B, C, or D trochlear dysplasia) were imported into the image analysis platform MeVisLab. A 3D Bone Volume Rendering (VR) and a virtual lateral radiograph was created. The anatomic femoral MPFL insertion was identified on the 3D VR. On virtual lateral radiographs, the MPFL insertion was identified based on landmarks described by Schöttle et al. using three different perspectives: Best possible overlap of the femoral condyles (BC) and a tangent along posterior border of the posterior femoral cortex (pBC); a tangent along the anterior border of the posterior cortex (aBC); and best possible overlap of the distal part of the posterior femoral cortex (BF). Distances between the anatomic attachment and radiographically obtained insertions were measured on the 3D VR and compared according to the type of trochlear dysplasia.
Significantly lower accuracy of fluoroscopy guided tunnel placement in MPFL reconstruction was found in knees with Type C and D dysplasia. This effect was observed irrespectively from the radiologic perspective (pBC, aBC, and FC). In the pBC view (highest accuracy), the mean distance from the centre of the anatomic MPFL attachment to the radiographically defined location was 4.3 mm in knees without trochlear dysplasia and increased to 4.8 mm in knees with Type A dysplasia, 3.8 mm in knees with Type B dysplasia, 6.7 mm (p < 0.001) in knees with Type C dysplasia, and 7.3 mm (p < 0.001) in knees with Type D dysplasia.
Radiographic landmark-based femoral tunnel placement in the pBC view provides highest accuracy in knees with a normal shaped trochlea or low grade trochlear dysplasia. In patients with severe dysplasia, fluoroscopy guided tunnel placement has a low accuracy, exceeding a critical threshold of 5 mm distance to the anatomic MPFL insertion irrespective of the radiographic perspective. In these patients, utilization of anatomic landmarks may be beneficial.
IV.
在进行内侧髌股韧带（MPFL）重建时，准确放置股骨隧道非常重要。本研究的目的是探讨滑车发育不良对透视引导下股骨隧道放置准确性的影响。
将 30 个膝关节（5 个滑车形态正常，10 个 A 型，5 个 B 型、C 型和 D 型滑车发育不良）的 CT 扫描导入图像分析平台 MeVisLab。创建了 3D 骨容积渲染（VR）和虚拟侧位片。在 3D VR 上识别解剖学股骨 MPFL 插入点。在虚拟侧位片上，根据 Schöttle 等人描述的标志，使用三种不同的透视角度（股骨髁最佳重叠和沿后股骨皮质后缘的切线（BC）；沿后皮质前缘的切线（aBC）；以及后股骨皮质远端的最佳重叠（BF））识别 MPFL 插入点。在 3D VR 上测量解剖附着点和影像学获得的插入点之间的距离，并根据滑车发育不良的类型进行比较。
在 C 型和 D 型发育不良的膝关节中，透视引导下 MPFL 重建的隧道放置准确性明显降低。这种效应在不同的影像学角度（BC、aBC 和 FC）下都观察到。在 BC 视图（最高准确性）中，无滑车发育不良膝关节的解剖 MPFL 附着中心点到影像学定义位置的平均距离为 4.3mm，A 型发育不良膝关节增加到 4.8mm，B 型发育不良膝关节增加到 3.8mm，C 型发育不良膝关节增加到 6.7mm（p<0.001），D 型发育不良膝关节增加到 7.3mm（p<0.001）。
在正常形态滑车或低级别滑车发育不良的膝关节中，基于影像学标志的股骨隧道在 BC 视图中提供了最高的准确性。在严重发育不良的患者中，透视引导下的隧道放置准确性较低，超过解剖 MPFL 插入点 5mm 的临界阈值，无论影像学角度如何。在这些患者中，使用解剖学标志可能是有益的。
IV。
