title: Effects of locking area on strength of 2- and 4-strand locking tendon repairs.
abstract: OBJECTIVE
  The area of the tendon within the locking suture configuration of the modified Pennington repair is an important determinant of eventual tendon strength. This 2-strand repair's loop configurations encompass a large cross-sectional area of the tendon. Many recently proposed repairs, however, consist of locks in a number of narrow sites on the tendon surface and most are multistranded. It is not clear how the area within the locks affects tendon strength and whether the effects of locking areas change according to the number of repair strands. In this study we investigate the effects of locking area on repair strength of 2- and 4-strand tendon repairs.
  
  
  METHODS
  Sixty-five fresh pig flexor tendons were divided equally into 6 groups and were transected completely. They were repaired with 2- or 4-strand techniques. The tendon-suture interface was a circle-locking junction and diameters of the locks were 1, 2, or 3 mm. The tendons were pulled in a tensile testing machine until failure of the repair and the mode of failure, 2-mm gap force, and ultimate strength were measured.
  
  
  RESULTS
  In the tendons with either 2- or 4-strand repairs locks with a diameter of 2 or 3 mm had significantly greater gap formation force and ultimate strength than those of 1 mm. The gap formation and ultimate forces were not statistically different between tendons with locks of 2 or 3 mm in diameter.
  
  
  CONCLUSIONS
  In both the 2- and 4-strand tendon repairs tested in this study repair strength increased as the diameter of locks of the repair increased from 1 mm to 2 or 3 mm. An increase in the diameter from 2 mm to 3 mm, however, did not increase the gap force and ultimate strength. These findings indicate that the cross-sectional area within the locks affects repair strength when the diameter of the locks is within a certain range (2 mm) and that further enlargement of the locking area does not increase strength.
authors.affiliation: Department of Hand Surgery, Hand Surgery Research Center, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China.
authors.forename: Ren Guo
authors.initials: RG
authors.lastname: Xie
authors.forename: Hong Guang
authors.initials: HG
authors.lastname: Xue
authors.forename: Jian Hui
authors.initials: JH
authors.lastname: Gu
authors.forename: Jun
authors.initials: J
authors.lastname: Tan
authors.forename: Jin Bo
authors.initials: JB
authors.lastname: Tang
mesh_terms: D000818:Animals; D022125:Lacerations / Q000601:surgery*; D008422:Materials Testing; D013536:Suture Techniques; D013552:Swine; D013708:Tendon Injuries / Q000601:surgery*; D013710:Tendons / Q000601:surgery*; D013718:Tensile Strength