title: Twisting and braiding reduces the tensile strength and stiffness of human hamstring tendon grafts used for anterior cruciate ligament reconstruction.
abstract: BACKGROUND
  Twisting and braiding of four-strand hamstring tendon grafts used for anterior cruciate ligament reconstruction has been proposed, but not proven, as a method of improving tensile properties.
  
  
  OBJECTIVE
  Twisting and braiding four-strand human hamstring tendon grafts will have no significant effect on initial graft strength or stiffness.
  
  
  METHODS
  Paired in vitro biomechanical study.
  
  
  METHODS
  In 12 matched cadaveric pairs, a doubled gracilis and semitendinosus tendon graft from one knee was twisted 180 degrees over a 30-mm length, while the doubled tendon graft from the contralateral knee was prepared for biomechanical testing with the graft strands in a parallel orientation. For an additional 12 matched pairs, a doubled graft was braided into a weave while the contralateral graft was prepared for testing in a parallel orientation. All four strands of each doubled tendon graft were equally tensioned with weights before being clamped in a tendon-freezing grip. Tensile testing was then performed.
  
  
  RESULTS
  Twisting decreased graft strength by 26% (P < 0.01) and stiffness by 43% (P < 0.01), while braiding reduced strength by 46% (P < 0.01) and stiffness by 54% (P < 0.01), compared with parallel-oriented grafts.
  
  
  CONCLUSIONS
  Equally tensioned, parallel four-strand human hamstring tendon grafts were significantly stronger and stiffer than twisted or braided four-strand hamstring tendon grafts.
  
  
  CONCLUSIONS
  We caution against the use of twisted or braided four-strand hamstring tendon grafts for anterior cruciate ligament reconstruction.
authors: Department of Orthopaedic Surgery, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors: David H
authors: DH
authors: Kim
authors: David R
authors: DR
authors: Wilson
authors: Aaron T
authors: AT
authors: Hecker
authors: Tobias M
authors: TM
authors: Jung
authors: Charles H
authors: CH
authors: Brown
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001696:Biomechanical Phenomena; D002102:Cadaver; D004548:Elasticity; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D008875:Middle Aged; D019651:Plastic Surgery Procedures; D013710:Tendons / Q000637:transplantation*; D013718:Tensile Strength