Application of CT-MRI Fusion-Based Three-Dimensional Reconstruction Technique in the Anatomic Study of Posterior Cruciate Ligament.

Objective: During PCL reconstruction surgery, precise and personalized positioning of the graft tunnel is very important. In order to obtain patient-specific anatomical data, we established a three-dimensional knee joint fusion model to provide a unified imaging strategy, as well as anatomical information, for individualized and accurate posterior cruciate ligament (PCL) reconstruction.

Methods: This is an exploration study. From January 2019 to January 2020, 20 healthy adults randomly were enrolled and assessed via CT and MRI imaging. A three-dimensional fusion model of the knee joint was generated using the modified MIMIMICS and image fusion software. On the fused image, the areas of the femoral and tibial PCL footprint of both knees were measured. The anatomical center of the PCL footprint was measured at the femoral and tibial ends. The relevant bony landmarks surrounding the PCL femoral and tibial attachment were also measured. Paired t-tests were employed for all statistical analyzes, and p < 0.05 was considered as statistically significant.

Results: All 20 subjects achieved successful image fusion modeling and measurement, with an average duration of 12 h. The lengths of the LF1-LF3 were 32.1 ± 1.8, 6.8 ± 2.5, and 23.3 ± 2.1 mm, respectively. The lengths of the LT1-LT3 were 37.3 ± 3.3, 45.6 ± 5.3, and 6.0 ± 1.2 mm, respectively. The distances between the tibial PCL center of the left knee to the medial groove, champagne-glass drop-off, and the apex of the medial intercondylar were 8.4 ± 2.4, 9.2 ± 1.8, and 15.3 ± 1.4 mm, respectively, and the corresponding distances from the right knee were 8.0 ± 2.0, 9.4 ± 2.2, and 16.1 ± 1.8 mm, respectively. We observed no difference between the bilateral sides, in terms of the distance from the PCL center to the PCL attachment-related landmark, under arthroscopic guidance. The area of the femoral and tibial PCL footprints on the left knee were 115.3 ± 33.5 and 146.6 ± 24.4 mm , respectively, and the corresponding areas on the right knee were 121.8 ± 35.6 and 142.8 ± 19.5 mm , respectively. There was no difference between the bilateral sides in terms of the PCL footprint areas.

Conclusion: In the fusion image, the PCL attachment center and relevant bony landmarks which can be easily identified under arthroscopy can be accurately measured. The model can also obtain personalized anatomical data of the PCL on the unaffected side of the patient, which can guide clinical PCL reconstruction.