title: Influence of core suture purchase length on strength of four-strand tendon repairs.
abstract: OBJECTIVE
  Recently the length of core suture purchase has been identified as a variable affecting the strength of tendon repairs. The influence of the length of the core suture purchase on the strength of multistrand locking and grasping suture repairs, however, has not been studied extensively in transversely lacerated tendons. We assessed the effects of the length of the core suture purchase on the strength of three 4-strand grasping or locking repair techniques.
  
  
  METHODS
  Seventy-four fresh adult pig flexor tendons were cut transversely and repaired with 1 of 3 methods: double-modified Kessler, locking cruciate, and modified Savage. Each method was assessed using 2 different lengths of core suture purchase (1.0 and 0.4 cm). The tendons were subjected to a linear noncyclic load-to-failure test in a tensile testing machine. We recorded the forces required for gap formation, ultimate strength, stiffness of the tendon, and the mode of repair failure.
  
  
  RESULTS
  The resistance to gap formation, the ultimate strength of all 3 repairs, and the stiffness of the tendons with the double-modified Kessler and modified Savage repairs decreased significantly as the length of core sutures decreased from 1.0 to 0.4 cm. Locking and grasping repairs had a similar decrease in strength when the purchase was decreased from 1.0 to 0.4 cm. All tendons with modified Savage repairs with 1.0-cm purchase failed by suture breakage and tendons with 0.4-cm purchase failed predominantly by pullout.
  
  
  CONCLUSIONS
  The length of core suture purchase significantly affects the strength of these 4-strand tendon repairs. The forces required for gap formation and the ultimate failure of repairs with 0.4-cm purchase were 20% to 45% lower than those of the repairs with 1.0-cm purchase. Locking repairs did not show a greater capacity to offset the decrease in strength than grasping repairs when the length of core suture purchase was decreased from 1.0 to 0.4 cm. Our study indicates that the length of suture purchase directly influences the strength of both locking and grasping core tendon repair methods.
authors.affiliation: Department of Hand Surgery, Hand Surgery Research Center, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Cao
authors.forename: Bei
authors.initials: B
authors.lastname: Zhu
authors.forename: Ren Guo
authors.initials: RG
authors.lastname: Xie
authors.forename: Jin Bo
authors.initials: JB
authors.lastname: Tang
mesh_terms: D000818:Animals; D013536:Suture Techniques; D013537:Sutures; D013552:Swine; D013708:Tendon Injuries / Q000601:surgery*; D013710:Tendons / Q000502:physiology* / Q000601:surgery*; D013718:Tensile Strength / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology