title: Sensitivity of predicted muscle forces during gait to anatomical variability in musculotendon geometry.
abstract: Scaled generic musculoskeletal models are commonly used to drive dynamic simulations of motions. It is however, acknowledged that not accounting for variability in musculoskeletal geometry and musculotendon parameters may confound the simulation results, even when analysing control subjects. This study documents the three-dimensional anatomical variability of musculotendon origins and insertions of 33 lower limb muscles determined based on magnetic resonance imaging in six subjects. This anatomical variability was compared to the musculotendon point location in a generic musculoskeletal model. Furthermore, the sensitivity of muscle forces during gait, calculated using static optimization, to perturbations of the musculotendon point location was analyzed with a generic model. More specific, a probabilistic approach was used: for each analyzed musculotendon point, the three-dimensional location was re-sampled with a uniform Latin hypercube method within the anatomical variability and the static optimization problem was then re-solved for all perturbations. We found that musculotendon point locations in the generic model showed only variable correspondences with the anatomical variability. The anatomical variability of musculotendon point location did affect the calculated muscle forces: muscles most sensitive to perturbations within the anatomical variability are iliacus and psoas. Perturbation of the gluteus medius anterior, iliacus and psoas induces the largest concomitant changes in muscle forces of the unperturbed muscles. Therefore, when creating subject-specific musculoskeletal models, these attachment points should be defined accurately. In addition, the size of the anatomical variability of the musculotendon point location was not related to the sensitivity of the calculated muscle forces.
authors.affiliation: KU Leuven, Department of Kinesiology, Human Movement Biomechanics, Tervuursevest 101, B-3001 Heverlee, Belgium.
authors.forename: Lode
authors.initials: L
authors.lastname: Bosmans
authors.affiliation: Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna, Italy.
authors.forename: Giordano
authors.initials: G
authors.lastname: Valente
authors.affiliation: KU Leuven, Department of Kinesiology, Human Movement Biomechanics, Tervuursevest 101, B-3001 Heverlee, Belgium.
authors.forename: Mariska
authors.initials: M
authors.lastname: Wesseling
authors.affiliation: KU Leuven, Department of Mechanical Engineering, Division PMA, Celestijnenlaan 300B, B-3001 Heverlee, Belgium.
authors.forename: Anke
authors.initials: A
authors.lastname: Van Campen
authors.affiliation: KU Leuven, Department of Mechanical Engineering, Division PMA, Celestijnenlaan 300B, B-3001 Heverlee, Belgium.
authors.forename: Friedl
authors.initials: F
authors.lastname: De Groote
authors.affiliation: KU Leuven, Department of Mechanical Engineering, Division PMA, Celestijnenlaan 300B, B-3001 Heverlee, Belgium.
authors.forename: Joris
authors.initials: J
authors.lastname: De Schutter
authors.affiliation: KU Leuven, Department of Kinesiology, Human Movement Biomechanics, Tervuursevest 101, B-3001 Heverlee, Belgium. Electronic address: Ilse.jonkers@faber.kuleuven.be.
authors.forename: Ilse
authors.initials: I
authors.lastname: Jonkers
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D005684:Gait / Q000502:physiology*; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008954:Models, Biological; D008962:Models, Theoretical; D009010:Monte Carlo Method; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology*; D012680:Sensitivity and Specificity; D013710:Tendons / Q000033:anatomy & histology* / Q000502:physiology*; D055815:Young Adult
keywords: Anatomical variability; Dynamic simulations; Muscle forces; Sensitivity analysis; Subject-specific musculoskeletal models