A novel 3D evaluation method for assessing bone to bone relationships in clubfoot

B. Ganesan, J. Yip, A. Al-Jumaily, S.S.M. Fong, S. Kothe Balasankar, A.M. Ey Batlle, K.N.K. Fong, A. Luximon

School of Biomedical Engineering, FEIT, University of Technology Sydney, Ultimo, NSW, Australia. Balasankar.Ganesan@student.uts.edu.au

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• Orthopedics

OBJECTIVE: Clubfoot is a complex congenital three-dimensional foot deformity, which affects 150,000-200,000 newborn babies annually around the world. A good understanding of the alignment of the two osseous columns and the lower leg of the ankle and foot complex is essential for evaluating the severity of clubfoot. The purposes of this study were to (1) develop an automated three-dimensional (3D) surface model of severe clubfoot based on two-dimensional (2D) slices of computed tomography (CT) images, (2) evaluate the alignment of foot bones relative to the ankle in severe clubfoot, and (3) examine the structural changes in the shape of the clubfoot.

PATIENTS AND METHODS: Two-dimensional CT image was taken from a four-year-old child with a severe clubfoot. Subsequently, an automated and detailed 3D surface model of the severe clubfoot was developed from the 2D images by using MATLAB software programming. Then, the x, y, and z coordinate angles were automatically calculated for each bone in the foot relative to the ankle (lower end of the tibia) to determine the orientations and relationships among the bones.

RESULTS: The relative position or orientation of each bone of the foot to the ankle of the severe clubfoot was objectively measured which was used to determine the orientation of each bone in the foot. Among the x, y, and z axes of the interested tarsal bones, the z axis represents the smallest moment of inertia, and the results showed that the bones in the x axis shifted medially with higher relative angle.

CONCLUSIONS: This 3D objective measurement method for assessing clubfoot can be used to determine and classify the severity of clubfoot, as well as evaluate and monitor the progress of the clubfoot intervention based on the relative position of the tarsal bones. The method can also be used to quantify the relationship between the tarsal bones of the foot and lower end of the tibia. In addition, angular measurements can be used to assess other pathological conditions of the foot such as pes cavus and pes planus.

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