title: A comparison of the fixation strengths provided by different intraosseous tendon lengths during anterior cruciate ligament reconstruction: a biomechanical study in a porcine tibial model.
abstract: BACKGROUND
  The purpose of this study was to determine the tibial fixation strength provided by different intraosseous soft tissue graft lengths within the tibial tunnel.
  
  
  METHODS
  Porcine tibial bones and digital flexor tendons were used for testing. Bone mineral densities of proximal tibial medial condyles were measured, and two-strand tendon bundles of 8 mm diameter were used. An intraosseous graft length of 2 cm was used in group 1 (n = 10), and a graft length of 4 cm was used in group 2 (n = 10). Tunnels were 4 cm in length and 8 mm in diameter. Tibial fixation was performed using a suture tied around a screw post with a washer and an additionally inserted 7 × 20 mm bioabsorbable screw. After applying preconditioning loading of 10 cycles, 1,000 cycles between 70-220 N were applied at a frequency of 1 Hz. Graft slippage and total graft movement were recorded. Ultimate tensile strength was measured by pull-out testing at an Instron crosshead speed of 1,000 mm/min.
  
  
  RESULTS
  No significant intergroup difference was found for total graft movement after cyclic loading (slippage in group 1, 1.2 mm and group 2, 1.2 mm, respectively, p = 0.917; and total graft movement in group 1, 3.3 mm and group 2, 2.7 mm, respectively, p = 0.199). However, mean ultimate tensile strength in group 2 was significantly higher than that in group 1 (group 1, 649.9 N; group 2, 938 N; p = 0.008).
  
  
  CONCLUSIONS
  In a porcine model, ultimate tensile strength was greater for a 4 cm long intraosseous flexor tendon in the tibial tunnel. However, no intergroup difference in graft slippage or total graft movement was observed. The results show that a 2 cm intraosseous graft length in the tibial tunnel is safe and has sufficient strength (> 450 N) for adequate rehabilitation after anterior cruciate ligament reconstruction.
authors.affiliation: Madipyunhan Orthopedic Clinic, Daegu, Korea.
authors.forename: Dong-Lyul
authors.initials: DL
authors.lastname: Yang
authors.affiliation: Park's Orthopedic Hospital, Daegu, Korea.
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Cheon
authors.affiliation: Department of Orthopaedic Surgery, Kyungpook National University School of Medicine, Daegu, Korea.
authors.forename: Chang-Wug
authors.initials: CW
authors.lastname: Oh
authors.affiliation: Department of Orthopaedic Surgery, Kyungpook National University School of Medicine, Daegu, Korea.
authors.forename: Hee-Soo
authors.initials: HS
authors.lastname: Kyung
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000503:physiopathology* / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction; D001696:Biomechanical Phenomena; D015519:Bone Density; D023421:Models, Animal; D013552:Swine; D013710:Tendons / Q000637:transplantation*; D013718:Tensile Strength; D013977:Tibia / Q000601:surgery*
keywords: Anterior cruciate ligament reconstruction; Biomechanical study; Fixation strength; Tendon length