title: Mechanical environment of the supraspinatus tendon: three-dimensional finite element model analysis.
abstract: BACKGROUND
  We analyzed the mechanical environment of the supraspinatus tendon using a three-dimensional finite element model with the software programs MENTAT and MARC.
  
  
  METHODS
  The supraspinatus tendon that attaches to the superior facet was extracted and modeled. The geometric shape of the humeral head was determined from computed tomography images, and the shape of the supraspinatus tendon was determined from magnetic resonance images of the shoulder at 0 degrees of abduction in a healthy 27-year-old man. The distal portion of the humeral head was fixed, and 10 N of tensile force was applied to the proximal end of the tendon. The tensile stress was calculated.
  
  
  RESULTS
  The tensile stress was 1.8 MPa for the bursal side and 15.0 MPa for the articular side of the anterior portion of the supraspinatus tendon. The intensity was 0 MPa for the bursal side and 4.5 MPa for the articular side of the middle portion of the tendon. The intensity was 0.1 MPa for the bursal side and 5.2 MPa for the posterior edge of the tendon.
  
  
  CONCLUSIONS
  Based on the three-dimensional finite element method, the maximal tensile stress was observed on the articular side of the anterior edge of the supraspinatus tendon. Our result may explain the frequent occurrence of rotator cuff tears at this site.
authors.affiliation: Division of Orthopedic Surgery, Department of Neuro and Locomotor Science, Akita University School of Medicine, Akita, Japan.
authors.forename: Nobutoshi
authors.initials: N
authors.lastname: Seki
authors.forename: Eiji
authors.initials: E
authors.lastname: Itoi
authors.forename: Yotsugi
authors.initials: Y
authors.lastname: Shibuya
authors.forename: Ikuko
authors.initials: I
authors.lastname: Wakabayashi
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Sano
authors.forename: Ryuji
authors.initials: R
authors.lastname: Sashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Minagawa
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Abe
authors.forename: Kazuma
authors.initials: K
authors.lastname: Kikuchi
authors.forename: Kyoji
authors.initials: K
authors.lastname: Okada
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Shimada
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D020342:Finite Element Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012785:Shoulder Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D013710:Tendons / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D014057:Tomography, X-Ray Computed