Description of patellar movement by 3D parameters obtained from dynamic CT acquisition

Author(s)

Rebelo, Marina de Sa ; Moreno, Ramon Alfredo ; Gobbi, Riccardo Gomes ; Camanho, Gilberto Luis ; Rodrigues de Avila, Luiz Francisco ; Demange, Marco Kawamura ; Pecora, Jose Ricardo ; Gutierrez, Marco Antonio ; Aylward, S ; Hadjiiski, LM

• Document type: Journal article
• Source: MEDICAL IMAGING 2014: COMPUTER-AIDED DIAGNOSIS; v. 9035, p. 9-pg., 2014-01-01.

Abstract

The patellofemoral joint is critical in the biomechanics of the knee. The patellofemoral instability is one condition that generates pain, functional impairment and often requires surgery as part of orthopedic treatment. The analysis of the patellofemoral dynamics has been performed by several medical image modalities. The clinical parameters assessed are mainly based on 2D measurements, such as the patellar tilt angle and the lateral shift among others. Besides, the acquisition protocols are mostly performed with the leg laid static at fixed angles. The use of helical multi slice CT scanner can allow the capture and display of the joint's movement performed actively by the patient. However, the orthopedic applications of this scanner have not yet been standardized or widespread. In this work we present a method to evaluate the biomechanics of the patellofemoral joint during active contraction using multi slice CT images. This approach can greatly improve the analysis of patellar instability by displaying the physiology during muscle contraction. The movement was evaluated by computing its 3D displacements and rotations from different knee angles. The first processing step registered the images in both angles based on the femur's position. The transformation matrix of the patella from the images was then calculated, which provided the rotations and translations performed by the patella from its position in the first image to its position in the second image. Analysis of these parameters for all frames provided real 3D information about the patellar displacement. (AU)

• FAPESP's process: 12/50878-0 - Dynamic CT for analysing patients with patellar instability before and after surgery
• Grantee: Gilberto Luís Camanho
• Support Opportunities: Regular Research Grants