2025 ISAKOS Biennial Congress ePoster
Quantitative Assessment of Knee Joint Kinematics In Patients with Recurrent Patellar Dislocation – Using a 3D-3D Surface Registration Technique and 4-D CT Analysis –
Kazuya Kaneda, MD, PhD, Shinjuku, Tokyo JAPAN
Kengo Harato, MD, PhD, Yokohama City, Kanagawa Prefecture JAPAN
Satoshi Oki, MD, PhD, Saitama, Saitama JAPAN
Yutaro Morishige, MD, PhD, Musashimurayama, Tokyo JAPAN
Shu Kobayashi, MD, PhD, Tokyo JAPAN
Yasuo Niki, MD, PhD, Tokyo JAPAN
Tatsuaki Matsumoto, MD, PhD, Shinjuku-Ku, Tokyo JAPAN
Ryo Sasaki, MD, PhD, Shinjuku-Ku, Tokyo JAPAN
Masaya Nakamura, MD, PhD, Tokyo JAPAN
Takeo Nagura, MD, Tokyo JAPAN
Department of Orthopedic Surgery, Keio University School of Medicine, Shinjuku-ku, Tokyo, JAPAN
FDA Status Cleared
Summary
This study demonstrates that patients with recurrent patellar dislocation exhibit earlier external tibial rotation compared to control groups, using advanced 4DCT imaging and 3D-3D surface registration techniques.
ePosters will be available shortly before Congress
Abstract
Introduction
Patellofemoral instability arises from multifactorial issues such as dysplasia, joint laxity, and patella alta. Clinically, it leads to recurrent lateral patellar dislocations and abnormal joint kinematics, notably the “J-sign.” This study aims to explore 3D kinematic alterations in patients with recurrent patellar dislocation using a novel approach combining 4DCT imaging and a 3D-3D surface registration technique, hypothesizing abnormal external tibial rotation.
Methods
This study included patients with recurrent patellar dislocation undergoing medial patellofemoral ligament reconstruction surgery. Exclusion criteria were permanent or habitual patellar dislocation, TT-TG distance >20 mm, additional surgeries, and joint laxity. Control knees had no history of patellar dislocation or ACL injury. The study enrolled 10 affected knees in 9 patients (1 male and 8 females; mean age, 25.8 ± 10.5 years) with recurrent patellar dislocation and 7 unaffected knees in 7 patients (2 males and 5 females; mean age, 32.6 ± 10.5 years) with unilateral anterior cruciate ligament injury, divided into dislocation and control groups, respectively. CT images were obtained using static CT and 4DCT. Static CT scanned both legs, including the femur, patella, and tibia. Dynamic 4DCT was performed with a 320-row CT scanner (Aquilion ONE; Canon Medical Systems) while patients extended their knees from 60° flexion to full extension. 5 frames of volumetric CT data were acquired every second, with an effective radiation dose of approximately 1.7 mSv. The innovative 3D-3D registration technique was used. 3D data of the femur, tibia, and patella were extracted using AVIZO software. Surfaces from 4DCT were matched to static CT using the iterative closest point algorithm, enabling the reproduction of leg motion during 4DCT. The 3D angles of the patella and tibia relative to the femur were evaluated. Differences between groups were analyzed using the Mann–Whitney U test. Statistical significance level was set at P<0.05. SPSS version 24.0 was used for statistical analyses.
Results
The clinical details of participants showed no significant differences in sex ratio, age, BMI, and Insall–Salvati ratio between groups. However, the sulcus angle and Tibial Tubercle – Trochlea Groove (TT-TG) distance were significantly different (P=0.003 and P=0.007, respectively), with the dislocation group showing larger values compared to the control group. Patellar rotation in the coronal plane showed no significant difference. In the dislocation group, lateral patellar tilt increased with knee extension, showing significant differences within 0°–20° of flexion (P<0.05). Tibial rotation exhibited external rotation in the dislocation group and normal screw-home movement in the control group, with significant differences within 0°–10° of flexion (P<0.05).
Discussion And Conclusion
This study supports the hypothesis that patients with recurrent patellar dislocation exhibit abnormal external tibial rotation. By employing the novel combination of 4DCT imaging and the 3D-3D surface registration technique, we observed the “J-sign” and significant differences in tibial rotation timing and magnitude between dislocation and control groups. The dislocation group showed earlier external tibial rotation during knee extension. This study has potential clinical applications in aiding surgical planning and providing prognostic value.