ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

The assessment of the intra-articular contact stress of the hip joint was performed in
different biomechanical studies. Experimental approaches based on in vitro and in vivo
methods are proposed for the direct measurement of the stress in the hip joint. Different
techniques such as pre-scaled sensitive films [7] and pressure transducers implanted into
patients’ hip prostheses are used [8]. Unfortunately these methods are either limited or
highly invasive and difficult to implement in non-operated hips. Therefore,
computational models based on mathematical functions and numerical models (e.g.,
Finite Element Method) [1,9] were proposed as alternative. These models were
successfully used in different applications, such as for analyzing the stress on
symptomatic and asymptomatic hips during daily activities [2,10]. However, these
studies present some limitations. In fact, analysis were performed by using not fully
subject-specific models (anatomical, kinematical and physical data) and the studied
movement are limited to routine activities (e.g., walking, climbing stairs) characterized
by low amplitudes. Consequently there is lack of numerical study for analyzing the hip
joint during excessive movements.
To address this issue, we present a numerical approach, where subject-specific models
resulting from the different methods are combined to analyze the biomechanical
behavior of the hip joint under movement. The hip analysis is performed for a female
professional ballet dancer performing four different extreme motions (Fig. 1).
Fig. 1: Examples of dancing postures.
For validation, the simulation results are compared with the results of clinical analysis
performed by radiologists.
3. PROPOSED APPROACH
The proposed approach (Fig. 2) uses non invasive modalities (Magnetic Resonance
Imaging (MRI), motion capture system and simulation models) computer graphics
techniques to create subject-specific models. From the subject MRI data, a segmentation
method based on discrete deformable models [11,12] is used to reconstruct the
anatomical models (bones and soft tissue). Since required in numerical simulation,
tetrahedral meshes are generated from the resulting anatomical models. To ensure the
simulation accuracy and stability, tetrahedral meshes with acceptable quality are created
by using a method exploiting deformable meshes and topological properties of the
reconstructed models [13,14]. According to the tissues properties and their attachments,