title: New equations to calculate 3D joint centres in the lower extremities.
abstract: Biomechanical movement analysis in 3D requires estimation of joint centres in the lower extremities and this estimation is based on extrapolation from markers placed on anatomical landmarks. The purpose of the present study was to quantify the accuracy of three established set of equations and provide new improved equations to predict the joint centre locations. The 'true' joint centres of the knee and ankle joint were obtained in vivo by MRI scans on 10 male subjects whereas the 'true' hip joint centre was obtained in 10 male and 10 female cadavers by CT scans. For the hip joint the errors ranged from 26.7 (8.9) to 29.6 (7.5) mm, for the knee joint 5.8 (3.1) to 22.6 (3.3) mm and for the ankle joint 14.4 (2.2) to 27.0 (4.6) mm. This differed significantly from the improved equations by which the error for the hip joint ranged from 8.2 (3.6) to 11.6 (5.6) mm, for the knee joint from 2.9 (2.1) to 4.7 (2.5) mm and for the ankle joint from 3.4 (1.3) to 4.1 (2.0) mm. The coefficients in the new hip joint equations differed significantly between sexes. This difference depends on anatomical differences of the male and female pelvis.
authors: Department of Neuroscience and Pharmacology, University of Copenhagen, 2200 Copenhagen, Denmark; Security Consulting, The Danish Institute of Fire and Security Technology, 2650 Hvidovre, Denmark. Electronic address: msc@dbi-net.dk.
authors: Martin
authors: M
authors: Sandau
authors: Department of Forensic Medicine, University of Copenhagen, 2100 Copenhagen, Denmark.
authors: Rikke V
authors: RV
authors: Heimbürger
authors: Department of Forensic Medicine, University of Copenhagen, 2100 Copenhagen, Denmark.
authors: Chiara
authors: C
authors: Villa
authors: Department of Radiology, Rigshospitalet, 2100 Copenhagen, Denmark.
authors: Karl E
authors: KE
authors: Jensen
authors: Department of Architecture, Design and Media Technology, Aalborg University, 9200 Aalborg, Denmark.
authors: Thomas B
authors: TB
authors: Moeslund
authors: Department of Informatics and Mathematics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
authors: Henrik
authors: H
authors: Aanæs
authors: Department of Neuroscience and Pharmacology, University of Copenhagen, 2200 Copenhagen, Denmark.
authors: Tine
authors: T
authors: Alkjær
authors: Department of Neuroscience and Pharmacology, University of Copenhagen, 2200 Copenhagen, Denmark.
authors: Erik B
authors: EB
authors: Simonsen
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D000886:Anthropometry; D005260:Female; D005684:Gait; D006621:Hip Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D012044:Regression Analysis; D012727:Sex Characteristics; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Biomechanics; Conventional Gait Model; Gait; Marker set; Motion analysis; Motion capture