title: Biomechanical testing of implant free wedge shaped bone block fixation for bone patellar tendon bone anterior cruciate ligament reconstruction in a bovine model.
abstract: BACKGROUND
  The use of an interference fit wedged bone plug to provide fixation in the tibial tunnel when using bone-patellar tendon-bone autograft for anterior cruciate ligament reconstruction offers many theoretic advantages including the potential to offer a more economical and biological alternative to screw fixation. This technique has not been subjected to biomechanical testing. We hypothesised that a wedged bone plug fixation technique provides equivalent tensile load to failure as titanium interference screw fixation.
  
  
  METHODS
  In a controlled laboratory setting, anterior cruciate ligament reconstruction was performed in 36 bovine knees using bone-patella-bone autograft. In 20 knees tibial fixation relied upon a standard cuboid bone block and interference screw. In eight knees a wedge shaped bone block with an 11 mm by 10 mm base without a screw was used. In a further eight knees a similar wedge with a 13 mm by 10 mm base was used. Each specimen used a standard 10 mm tibial tunnel. The reconstructions were tested biomechanically in a physiological environment using an Instron machine to compare ultimate failure loads and modes of failure.
  
  
  RESULTS
  Statistical analysis revealed no significant difference between wedge fixation and screw fixation (p = 0.16), or between individual groups (interference screw versus 11 mm versus 13 mm wedge fixation) (P = 0.35).
  
  
  CONCLUSIONS
  Tibial tunnel fixation using an impacted wedge shaped bone block in anterior cruciate ligament reconstruction has comparable ultimate tensile strength to titanium interference screw fixation.
authors.affiliation: Sportsmed SA, 32 Payneham Road, Adelaide, Australia. chas@willis-owen.co.uk.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Willis-Owen
authors.forename: Trevor C
authors.initials: TC
authors.lastname: Hearn
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Keene
authors.forename: John J
authors.initials: JJ
authors.lastname: Costi
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