title: Effect of shoulder abduction on the fixation of humeral greater tuberosity fractures: a biomechanical study for three types of fixation constructs.
abstract: BACKGROUND
  An abduction brace and abduction exercises are commonly employed after humeral greater tuberosity fracture repair. However, the effects of glenohumeral abduction on the biomechanical strength have seldom been elucidated.
  
  
  METHODS
  We studied 24 pairs of female fresh frozen porcine shoulders randomly divided into 3 groups. After creation of a greater tuberosity fracture on each shoulder, 3 fixation techniques were used for the 3 groups: double-row suture anchor fixation (DR), suture bridge technique (SB), and 2-screw fixation (TS). This biomechanical study was conducted to compare the forces that create 3- and 5-mm displacements and the ultimate failure load at the simulated shoulder abduction angles of 0° and 45° among the 3 groups.
  
  
  RESULTS
  In the DR group, the mean forces to create 3- and 5-mm displacements and the failure load at 0° were higher than those at 45° (P = .036, P = .012, P = .027). By contrast, in the SB group, the mean forces to create 3- and 5-mm displacements at 45° were greater than those at 0° (P = .012, P = .012). There were no significant differences in the forces to create 3- and 5-mm displacements and construct failure between 0° and 45° in the TS group (P = .575, .327, .478).
  
  
  CONCLUSIONS
  The DR group had greatest initial fixation strength at a low abduction angle, whereas the SB group had the highest initial fixation strength at a high abduction angle. The TS group appeared unaffected by the abduction angle.
authors.affiliation: Institute of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan; Department of Orthopaedics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Cheng-Li
authors.initials: CL
authors.lastname: Lin
authors.affiliation: Institute of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan; Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Fong-Chin
authors.initials: FC
authors.lastname: Su
authors.affiliation: Department of Medicine, School of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chih-Hsun
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Department of Medicine, School of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chih-Kai
authors.initials: CK
authors.lastname: Hong
authors.affiliation: Department of Orthopaedics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan.
authors.forename: I-Ming
authors.initials: IM
authors.lastname: Jou
authors.affiliation: Department of Orthopaedics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chii-Jeng
authors.initials: CJ
authors.lastname: Lin
authors.affiliation: Department of Orthopaedics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan. Electronic address: suwr@ms28.hinet.net.
authors.forename: Wei-Ren
authors.initials: WR
authors.lastname: Su
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001863:Bone Screws; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D006810:Humeral Fractures / Q000601:surgery*; D006811:Humerus / Q000601:surgery; D012785:Shoulder Joint / Q000601:surgery*; D053441:Suture Anchors; D013536:Suture Techniques; D013552:Swine; D016474:Weight-Bearing
keywords: Humeral greater tuberosity fracture; abduction; biomechanics; screw; surgery; suture anchor