A Statistical Shape Model of Femur of ACL-Injured Knee

Abstract Injuries to the anterior cruciate ligament (ACL) are common among active populations. The shape and anatomical variations of the bones are directly related to the function of the ACL, and therefore are considered to be risk factors for injury. This research aims to delineate the key patterns of shape variation in femurs affected by ACL injuries through the application of Statistical Shape Modelling (SSM). SSM is applied to 50 distal femur models and their modes of variations are described. Ten morphologically significant parameters of the distal femur bone are selected and measured on a 3D model of the mean femur, as well as the −3SD and +3SD shapes of the first three principal components (PCs). The first principal component reflects the variation in size of the femur. The second principal component is mainly related to the width of the notch. A variation in the height of the medial posterior condyle is observed in the third principal component. Nevertheless, it is not as significant as with the first two PCs. The study presents a statistical shape model for characterizing the fundamental modes of geometric variation in femoral bones following an ACL injury. Knowing the bony morphological features associated with ACL injuries is crucial to tailoring treatment plans to each individual.