title: Compaction of a bone dowel in the tibial tunnel improves the fixation stiffness of a soft tissue anterior cruciate ligament graft: an in vitro study in calf tibia.
abstract: BACKGROUND
  Despite increasing attention on fixation of a soft tissue anterior cruciate ligament graft in the tibia, there have been no studies on the use of a bone dowel as a joint line fixation device for promoting fixation properties, especially stiffness at the time of implantation.
  
  
  OBJECTIVE
  To determine whether compacting a bone dowel into the tibial tunnel improves fixation stiffness, yield load, and resistance to slippage of a soft tissue anterior cruciate ligament graft.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  A double-looped tendon graft was fixed at the distal end of the tibial tunnel with a WasherLoc in 24 calf tibias. The tibial tunnels were treated with or without a dowel of cancellous bone. The bone dowel was harvested from the tibial tunnel and then compacted into a tapered space anterior to the anterior cruciate ligament graft as a joint line fixation device. A cyclic load and measurement test was administered to determine fixation stiffness, yield load, slippage, and failure mode.
  
  
  RESULTS
  The specimens with the bone dowel had 58 N/mm more stiffness (P = .04); however, the yield load and resistance to slippage were similar in specimens with and without the bone dowel.
  
  
  CONCLUSIONS
  A bone dowel harvested from the tibial tunnel can be used as a joint line fixation device in series with a distal fixation method to improve initial fixation stiffness and increase the fit, which is known to enhance tendon graft-to-bone healing in the tibia.
authors.affiliation: Department of Mechanical Engineering, University of California at Davis, Davis, CA, USA. sebhowell@mac.com
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Howell
authors.forename: Phil
authors.initials: P
authors.lastname: Roos
authors.forename: Maury L
authors.initials: ML
authors.lastname: Hull
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000503:physiopathology* / Q000601:surgery*; D001858:Bone Nails; D002417:Cattle; D004195:Disease Models, Animal; D004548:Elasticity; D016268:Internal Fixators; D008422:Materials Testing; D019637:Orthopedic Procedures / Q000295:instrumentation* / Q000379:methods*; D013977:Tibia / Q000601:surgery*; D017211:Treatment Failure; D016474:Weight-Bearing