A Faust

Publications (2)2.43 Total impact

• Article: Three-dimensional dynamic hip contact area and pressure distribution during activities of daily living.

  H Yoshida, A Faust, J Wilckens, M Kitagawa, J Fetto, Edmund Y-S Chao
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  ABSTRACT: Estimation of the hip joint contact area and pressure distribution during activities of daily living is important in predicting joint degeneration mechanism, prosthetic implant wear, providing biomechanical rationales for preoperative planning and postoperative rehabilitation. These biomechanical data were estimated utilizing a generic hip model, the Discrete Element Analysis technique, and the in vivo hip joint contact force data. The three-dimensional joint potential contact area was obtained from the anteroposterior radiograph of a subject and the actual joint contact area and pressure distribution in eight activities of daily living were calculated. During fast, normal, and slow walking, the peak pressure of moderate magnitude was located at the lateral roof of the acetabulum during mid-stance. In standing up and sitting down, and during knee bending, the peak pressures were located at the edge of the posterior horn and the magnitude of the peak pressure during sitting down was 2.8 times that of normal walking. The peak pressure was found at the lateral roof in climbing up stairs which was higher than that in going down stairs. These results can be used to rationalize rehabilitation protocols, functional restrictions after complex acetabular reconstructions, and prosthetic component wear and fatigue test set up. The same model and analysis can provide further insight to soft tissue loading and pathology such as labral injury. When the pressure distribution on the acetabulum is inverted onto the femoral head, prediction of subchondral bone collapse associated with avascular necrosis can be achieved with improved accuracy.
  Journal of Biomechanics 02/2006; 39(11):1996-2004. · 2.43 Impact Factor
• Article: Virtual reality (VR) techniques in orthopaedic research and practice.

  E Y Chao, P Barrance, E Genda, N Iwasaki, S Kato, A Faust
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  ABSTRACT: Modeling the musculoskeletal joint system using biomechanical analysis and computer graphics techniques allows us to visualize normal, diseased and reconstructed joint function. This model can be used to study the loading of bones and joints under theoretical and simulated activities. In this study, intact cadavers were imaged using MRI, CT scanning and cryo-sectioning techniques. Using sequential pixel information of bone and soft tissue boundaries collected from digital camera images, MRI and CT scans, the volumetric models of the musculoskeletal joint system are reconstructed. "Descriptive geometry" techniques which treat bones as rigid bodies and cartilage, ligament and muscles as deformable bodies were used to construct the model. Joint resultant forces and moments were determined using an inverse dynamics formulation, while ligament tension, joint contact pressure, and bone stresses are solved through a simplified Rigid Body Spring Modeling technique and the Finite Element Method. The results under static and dynamic loading activities can be visualized using interactive computer graphics. The advantages of such a model are the elimination of the need for large numbers of intact cadaveric specimens, and the unprecedented capability to study joint loading responses under normal, abnormal and surgically reconstructed states. Such a model and its analytical capability are ideal for pre-operative planning and computer-assisted orthopaedic surgery. This Visual, Interactive, Computational, and Anatomic Model(VICAM) and its associated analysis capability represent the next generation of technology which will have an enormous impact in orthopaedic research, education and patient care.
  Studies in health technology and informatics 02/1997; 39:107-14.