Related Experiment Video
Updated: May 7, 2025
Four-Dimensional CT Analysis Using Sequential 3D-3D Registration
Published on: November 23, 2019
Analysis of spatial patellofemoral alignment using novel three-dimensional measurements based on weight-bearing
Yurou Chen1, Fan Yu1, Fanzhuang Rong2
1Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
Objectives:
To propose a reliable and standard 3D assessment method to analyze the effect of weight-bearing (WB) status on the location of patella and clarify the diagnostic performance of 3D parameters for recurrent patellar dislocation (RPD) in WB and non-weight-bearing (NWB) conditions.
Methods:
Sixty-five knees of RPD patients and 99 knees of controls were included. Eight landmarks, two lines and a coordinate system were defined on 3D bone models of knees based on weight-bearing CT and non-weight-bearing CT. The shift and tilt of patella in three orthogonal axes (Xshift, Yshift, Zshift, Xtilt, Ytilt, Ztilt) were evaluated.
Results:
Xshift and Yshift were significantly higher, Zshift, Xtilt and Ytilt were significantly lower in WB condition than NWB condition (p < 0.001, p < 0.001, p = 0.001, p = 0.002, p = 0.010). In both WB and NWB conditions, Xshift, Yshift and Ztilt were significantly higher, and Xtilt was significantly lower in the RPD group than the control group (WB/NWB: p < 0.001/p = 0.002, p < 0.001/p = 0.001, p < 0.001/p < 0.001, p < 0.001/p = 0.009). In WB condition, Zshift and Ytilt were significantly higher in the RPD group than the control group (p = 0.011, p < 0.001). Ztilt had the best diagnostic performance for RPD in both WB and NWB conditions, with AUC of 0.887 (95% CI: 0.828, 0.946) and 0.885 (95% CI: 0.822, 0.947), respectively.
Conclusions:
The 3D measurement method reliably and comprehensively reflected the relative spatial position relationship of the patellofemoral joint. It can be applied to the 3D preoperative planning of patellofemoral procedures. In addition, patellofemoral evaluation under the WB condition was essential to detect subtle underlying risk factors for RPD, with axial lateral patellar tilt being the best predictor.
Critical Relevance Statement:
This 3D measurement method under weight-bearing conditions contributes to comprehensively describing the relative spatial position of the patellofemoral joint in a standardized way and can be applied to preoperative evaluation for recurrent patellar dislocation.
Key Points:
Patellofemoral alignment is a 3D problem, and the accuracy of 2D parameters has been questioned. 3D measurement was reliable and comprehensively reflected relative spatial relationships of the patellofemoral joint. 3D measurements under weight-bearing condition help preoperative evaluation for RPD.
