title: Effect of shoulder abduction angle on biomechanical properties of the repaired rotator cuff tendons with 3 types of double-row technique.
abstract: BACKGROUND
  After rotator cuff repair, the shoulder is immobilized in various abduction positions. However, there is no consensus on the proper abduction angle.
  
  
  OBJECTIVE
  To assess the effect of shoulder abduction angle on the biomechanical properties of the repaired rotator cuff tendons among 3 types of double-row techniques.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Thirty-two fresh-frozen porcine shoulders were used. A simulated rotator cuff tear was repaired by 1 of 3 double-row techniques: conventional double-row repair, transosseous-equivalent repair, and a combination of conventional double-row and bridging sutures (compression double-row repair). Each specimen underwent cyclic testing followed by tensile testing to failure at a simulated shoulder abduction angle of 0° or 40° on a material testing machine. Gap formation and failure loads were measured.
  
  
  RESULTS
  Gap formation in conventional double-row repair at 0° (1.2 ± 0.5 mm) was significantly greater than that at 40° (0.5 ± 0.3mm, P = .01). The yield and ultimate failure loads for conventional double-row repair at 40° were significantly larger than those at 0° (P < .01), whereas those for transosseous-equivalent repair (P < .01) and compression double-row repair (P < .0001) at 0° were significantly larger than those at 40°. The failure load for compression double-row repair was the greatest among the 3 double-row techniques at both 0° and 40° of abduction.
  
  
  CONCLUSIONS
  Bridging sutures have a greater effect on the biomechanical properties of the repaired rotator cuff tendon at a low abduction angle, and the conventional double-row technique has a greater effect at a high abduction angle.
  
  
  CONCLUSIONS
  Proper abduction position after rotator cuff repair differs between conventional double-row repair and transosseous-equivalent repair. The authors recommend the use of the combined technique of conventional double-row and bridging sutures to obtain better biomechanical properties at both low and high abduction angles.
authors.affiliation: Shoulder and Elbow Surgery and Sports Medicine, Department of Orthopedic Surgery, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka, Japan. tmihata@yahoo.co.jp
authors.forename: Teruhisa
authors.initials: T
authors.lastname: Mihata
authors.forename: Tetsutaro
authors.initials: T
authors.lastname: Fukuhara
authors.forename: Bong Jae
authors.initials: BJ
authors.lastname: Jun
authors.forename: Chisato
authors.initials: C
authors.lastname: Watanabe
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kinoshita
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D007103:Immobilization / Q000379:methods / Q000502:physiology; D019637:Orthopedic Procedures / Q000379:methods*; D017006:Rotator Cuff / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D012421:Rupture / Q000503:physiopathology / Q000601:surgery; D012785:Shoulder Joint / Q000502:physiology*; D013536:Suture Techniques; D013552:Swine