title: Biomechanical testing of epitenon suture strength in Achilles tendon repairs.
abstract: BACKGROUND
  Recent evidence that early, active mobilization protocols after Achilles tendon repairs increase recovery speed and strength make operative repair strength critical to positive outcomes after Achilles tendon ruptures. While previous research has focused on core (tendon proper) repair techniques, no previous literature has reported testing of core repairs augmented with epitenon sutures, which have been shown to increase the strength of repairs of flexor tendons of the hand.
  
  
  METHODS
  Five matched pairs of fresh frozen human Achilles tendons were tested with and without the addition of an epitenon suture to the core repair suture. All specimens were repaired using a No. 2 Ethibond Krakow locking loop core suture. The epitenon suture was added to one tendon randomly chosen from each pair, using a 4-0 nylon suture. All specimens were mounted on an MTS testing machine (MTS Systems Corp., Eden Prairie, MN) and loaded to failure, which was defined as a 1-cm gap formation.
  
  
  RESULTS
  The addition of epitenon sutures significantly increased the force necessary to produce a 2-mm gap as compared to core sutures alone by 74%, and it increased the average load to failure by 119%. Also, initial tendon stiffness was 173% greater in tendons reinforced with epitenon sutures.
  
  
  CONCLUSIONS
  This study demonstrates that greater resistance to gap formation, approximation of tissue ends, and tensile strength were achieved by the addition of an epitenon suture. Clinical relevance may improve healing by decreased gap formation at the repair site and a lower risk of adhesion formation.
authors.affiliation: Department of Human Biology, Stanford University, Stanford, CA, USA.
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Shepard
authors.forename: Derek P
authors.initials: DP
authors.lastname: Lindsey
authors.forename: Loretta B
authors.initials: LB
authors.lastname: Chou
mesh_terms: D000125:Achilles Tendon / Q000503:physiopathology / Q000601:surgery*; D001696:Biomechanical Phenomena; D002102:Cadaver; D006801:Humans; D008422:Materials Testing; D012421:Rupture / Q000601:surgery; D013536:Suture Techniques; D013537:Sutures / Q000592:standards*; D013708:Tendon Injuries / Q000601:surgery*; D013718:Tensile Strength