Document Type : Full Research Paper

Authors

• Mina Gharenazifam ¹
• Ehsan Arbabi ²

¹ M.Sc. Student, Department of Biomedical Engineering, Amirkabir University of Technology

² Assistant Professor, School of Electrical and Computer Engineering, College of Engineering, University of Tehran

Abstract

One of the main causes of early osteoarthritis of the hip is Femoroacetabular Impingement (FAI). When the femoral head loses its spherical shape at head-neck junction, a special type of impingement, called Cam impingement, occurs. Alpha angle can be used as a geometric parameter for evaluating this kind of anatomic deformity. In this article we propose a fully automatic strategy for estimating alpha angle by analyzing 3D data. In the proposed strategy a radial plane around the femoral head-neck axis is rotated in order to provide alpha angles in different orientations. For evaluating the proposed method, the alpha angle of twelve 3D femur models of female subjects, reconstructed from magnetic resonance images (including both right and left femur), have been estimated. The mean and standard deviation of these estimated alpha angles have been found to be in good agreement with the expected values for alpha angle in healthy human. In addition, the effect of the data resolution on the provided results has been evaluated in terms of accuracy and speed, by using four different resolutions of 3D meshes. The results indicate that using 64 times lower data resolution can increase the computational speed up to about 8 times and add an average error of about 2° to the estimated alpha angles.

Keywords

• Hip
• Femoroacetabular Impingement (FAI)
• Magnetic Resonance Images (MRI)
• 3D Mesh

Main Subjects

• Biomechanics of Bone / Bone Biomechanics
• Biomedical Image Processing / Medical Image Processing