2025 ISAKOS Biennial Congress ePoster
Morphological risk of the femur causing anterior cruciate ligament (ACL) injuries : comparative 3-Dimensional mean model analysis of ACL and non-injured patients
Soheun Lee, PhD, Seoul, Gangnam-gu KOREA, REPUBLIC OF
Min Jung, MD, PhD, Seoul KOREA, REPUBLIC OF
Kwangho Chung, MD, Seoul KOREA, REPUBLIC OF
Hyun-Soo Moon, MD, PhD, Seoul KOREA, REPUBLIC OF
Se-Han Jung, MD, Seoul KOREA, REPUBLIC OF
Sung-Hwan Kim, MD, PhD, Seoul KOREA, REPUBLIC OF
Gangnam Severance Hospital, Yonsei University, Seoul, Gangnam-gu, KOREA, REPUBLIC OF
FDA Status Not Applicable
Summary
NWI, the width of the notch enterance, is more meaningful than the volume and shape of the notch. The volume of the lateral supracondylar ridge in the femur diaphysis increases. When the femur tilts outward, the size of the posterior lateral condyle increases, causing knee instability.Therefore, when the femur rotates externally, ACL rupture occurs at the lateral condyle.
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Abstract
Introduction
Several bone morphological parameters have been investigated as risk factors for ACL injuries. However, most measurements were made indirectly in 2-dimesion (D) and there has never been a clear agreement in 3-D. Therefore, the purpose of this study is to create an SSM (Statistical Shape Model) of the femur based on 3D-CT. Then, the morphological risk factors of the ACL are found by extracting them with STL and comparing them directly in 3-D.
Materials And Methods
One-sided CT images were acquired and analyzed for 120 subjects with ACL rupture and 120 subjects in the control group. Using Mimics(Materialise, Belgium), 3-D models are created for 60 right and 60 left ACL ruptured patients, and 60 right and 60 left control patients. The 3D model of the 60 people on the left is changed to the 60 people on the right using Mirror in 3-Matics (Materialise, Belgium). To form the 120 models on the right into one average model, use 3-Matics' SSM module (or House made MATLAB, which matches the topology to the value where Difference, the difference between the average and total volume, is min) and extracted with STL. After adjusting the transepicondylar width to the same size, an analysis was performed using 3-Matics' Create Part Comparison Analysis to visualize the surface differences between 3D models as images.
Results
Differences in shape were detected in the knees of ACL patients and controls. This means that this is a common appearance for ACL patients who are prone to ACL injuries. The most common type of ACL patient is known as "A-shaped," in which the notch is the same depth but both walls are narrower. There was no difference in the size (volume and shape) of the medial condyle in ACL patients compared to the control group. As the sides of the medial epicondyle shrink and the medial condyle moves inward, its volume increases, narrowing the notch width. Lateral condyle is large posteriorly and increases in volume inward. Therefore NWI, the width of the notch enterance, is more meaningful than the volume and shape of the notch. The volume of the lateral supracondylar ridge in the femur diaphysis increases. When the femur tilts outward, the size of the posterior lateral condyle increases, causing knee instability. Therefore, when the femur rotates externally, ACL rupture occurs at the vulnerable position of the lateral condyle.
Conclusion
3D CT-based bone shape quantification can identify morphological risk factors for ACL injury. When performing ACL reconstruction surgery, notch plasty is necessary to prevent impingement of the graft tendon. A better understanding of the role of bone shape could help to identify subjects at increased risk for ACL injuries and to develop targeted prevention or surgical strategies.
Keywords: Femur, Intercondylar notch, Anterior cruciate ligament, ACL, Morphology, Risk factor, SSM, Statistical Shape Model