title: Dynamic 3D scanning as a markerless method to calculate multi-segment foot kinematics during stance phase: methodology and first application.
abstract: Multi-segmental foot kinematics have been analyzed by means of optical marker-sets or by means of inertial sensors, but never by markerless dynamic 3D scanning (D3DScanning). The use of D3DScans implies a radically different approach for the construction of the multi-segment foot model: the foot anatomy is identified via the surface shape instead of distinct landmark points. We propose a 4-segment foot model consisting of the shank (Sha), calcaneus (Cal), metatarsus (Met) and hallux (Hal). These segments are manually selected on a static scan. To track the segments in the dynamic scan, the segments of the static scan are matched on each frame of the dynamic scan using the iterative closest point (ICP) fitting algorithm. Joint rotations are calculated between Sha-Cal, Cal-Met, and Met-Hal. Due to the lower quality scans at heel strike and toe off, the first and last 10% of the stance phase is excluded. The application of the method to 5 healthy subjects, 6 trials each, shows a good repeatability (intra-subject standard deviations between 1° and 2.5°) for Sha-Cal and Cal-Met joints, and inferior results for the Met-Hal joint (>3°). The repeatability seems to be subject-dependent. For the validation, a qualitative comparison with joint kinematics from a corresponding established marker-based multi-segment foot model is made. This shows very consistent patterns of rotation. The ease of subject preparation and also the effective and easy to interpret visual output, make the present technique very attractive for functional analysis of the foot, enhancing usability in clinical practice.
authors.affiliation: Mobilab, Thomas More University College, Belgium.
authors.forename: Inge
authors.initials: I
authors.lastname: Van den Herrewegen
authors.affiliation: Mobilab, Thomas More University College, Belgium.
authors.forename: Kris
authors.initials: K
authors.lastname: Cuppens
authors.affiliation: Mobilab, Thomas More University College, Belgium. Electronic address: mario.broeckx@thomasmore.be.
authors.forename: Mario
authors.initials: M
authors.lastname: Broeckx
authors.affiliation: Medical Clinic, Department of Sports Medicine, University of Tuebingen, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Barisch-Fritz
authors.affiliation: Department of Mechanical Engineering, Faculty of Engineering KU Leuven, Belgium.
authors.forename: Jos
authors.initials: J
authors.lastname: Vander Sloten
authors.affiliation: Movement Analysis Laboratory, Istituti Ortopedici Rizzoli, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Leardini
authors.affiliation: Mobilab, Thomas More University College, Belgium; Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Science KU Leuven, Belgium.
authors.forename: Louis
authors.initials: L
authors.lastname: Peeraer
mesh_terms: D000328:Adult; D000465:Algorithms; D001696:Biomechanical Phenomena; D002111:Calcaneus / Q000033:anatomy & histology / Q000502:physiology*; D005260:Female; D005528:Foot / Q000033:anatomy & histology / Q000502:physiology*; D006214:Hallux / Q000033:anatomy & histology / Q000502:physiology; D064368:Healthy Volunteers; D006365:Heel / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008684:Metatarsus / Q000033:anatomy & histology / Q000502:physiology; D008875:Middle Aged; D015203:Reproducibility of Results; D012399:Rotation; D055815:Young Adult
keywords: 4D scanning; Dynamic 3D scanning; Foot kinematics; Joint rotations; Multi-segment foot model