title: Predicting failures of suture anchors used for rotator cuff repair: a CT-based 3-dimensional finite element analysis.
abstract: BACKGROUND
  Failure of inserted anchors has been recognized as one of the major pathomechanisms of re-tearing after rotator cuff repair.
  
  
  OBJECTIVE
  To predict the inserted anchor failure using CT-based 3-dimensional finite element method (CT/3D-FEM).
  
  
  METHODS
  Among twenty patients who underwent rotator cuff repair, 5 had anchor failure (failed anchor group) and 15 had no anchor failure (stable anchor group). A 3D model of proximal humerus was developed for each patient based on the CT data. A virtual pullout testing of TWINFIX™ anchors inserted into bone at 6 different sites was performed using FEM. Then, mean failure load of 6 anchors for each patient was compared between two groups. Moreover, an optimal cut-off value of the mean failure load was determined for predicting anchor failure.
  
  
  RESULTS
  The mean failure load in the failed anchor group (70.3 N) was significantly lower than that in the stable anchor group (119.0 N; p<0.0001). In our method, the optimum cut-off value of the mean failure load was 75.4 N.
  
  
  CONCLUSIONS
  Failure of the inserted TWINFIX™ anchor could be predicted using CT/3D-FEM. In this method, there seemed to be a high risk of anchor failure in shoulders with a mean failure load of <75.4 N.
authors.affiliation: Division of Orthopedics, Sendai City Hospital, Sendai, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Sano
authors.affiliation: Division of Orthopedics, Saiseikai Matsuyama Hospital, Ehime, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Imagawa
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Yamamoto
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ozawa
authors.affiliation: Department of Nano Mechanics, Graduate School of Engineering, Tohoku University, Sendai, Japan.
authors.forename: A Toshimitsu
authors.initials: AT
authors.lastname: Yokobori
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Itoi
mesh_terms: D000368:Aged; D019245:Compressive Strength; D003198:Computer Simulation; D055119:Elastic Modulus; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000379:methods; D020342:Finite Element Analysis; D017276:Friction; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging / Q000502:physiology* / Q000503:physiopathology*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008875:Middle Aged; D008954:Models, Biological; D011859:Radiography; D018570:Risk Assessment / Q000379:methods; D017006:Rotator Cuff / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000601:surgery; D000070636:Rotator Cuff Injuries; D013314:Stress, Mechanical; D053441:Suture Anchors; D013718:Tensile Strength
keywords: Rotator cuff repair; computed tomography; finite element method; pullout strength; suture anchor