title: Patient-specific bone geometry and segment inertia from MRI images for model-based analysis of pathological gait.
abstract: Patient-specific modeling is a vital component in the translation of computational multibody dynamics into clinical practice. Recent research has focused on ways to derive such models from medical imaging, but the process is usually time consuming and sensitive to operator skill. Here, we present methods to derive kinematic and inertial properties of body segments from MRI images, and condense them into a dynamically consistent patient-specific multibody model (PSM). We develop a semi-automated tool chain to classify bone, muscle and fat in the lower body and use optimization and geometrical methods to derive personalized bone meshes and segment inertial properties. The tool chain is applied to investigate the gait of a 12-yr old female with bone deformities. The patient-specific results are compared to those arising from generic scaled models with parameters based on regression equations. We found several kinematic and inertial differences between the two models, and overall the PSM resulted in markedly smaller angular and force residuals. The PSM was able to capture vital aspects of this patient׳s gait in the transverse plane that were overlooked by the generic model. These results are relevant to the use of multibody dynamics in the planning of surgical interventions, and form the basis for developing efficient and automatic methods to create patient-specific models.
authors.affiliation: Optimization in Robotics & Biomechanics, Interdisciplinary Center for Scientific Computing, University of Heidelberg, Berlinerstr. 45, Heidelberg 69120, Germany. Electronic address: manish.sreenivasa@iwr.uni-heidelberg.de.
authors.forename: Manish
authors.initials: M
authors.lastname: Sreenivasa
authors.affiliation: Optimization in Robotics & Biomechanics, Interdisciplinary Center for Scientific Computing, University of Heidelberg, Berlinerstr. 45, Heidelberg 69120, Germany.
authors.forename: Carlos Javier Gonzalez
authors.initials: CJG
authors.lastname: Chamorro
authors.affiliation: Optimization in Robotics & Biomechanics, Interdisciplinary Center for Scientific Computing, University of Heidelberg, Berlinerstr. 45, Heidelberg 69120, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gonzalez-Alvarado
authors.affiliation: Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Schlierbacher Landstr. 200a, 69118 Heidelberg, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Rettig
authors.affiliation: Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Schlierbacher Landstr. 200a, 69118 Heidelberg, Germany.
authors.forename: Sebastian I
authors.initials: SI
authors.lastname: Wolf
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging / Q000503:physiopathology; D001696:Biomechanical Phenomena; D001842:Bone and Bones / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002648:Child; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009132:Muscles / Q000000981:diagnostic imaging / Q000503:physiopathology; D010009:Osteochondrodysplasias / Q000000981:diagnostic imaging / Q000503:physiopathology*; D066230:Patient-Specific Modeling
keywords: Bone morphing; MRI segmentation; Pathological gait dynamics; Patient-specific modeling