title: Comparison of single- versus double-tunnel tendon-to-bone healing in an ovine model: a biomechanical and histological analysis.
abstract: BACKGROUND
  The double-bundle technique has recently gained much interest in ligament reconstruction. In addition to potential kinematic advantages, perhaps double tunnels have the potential for faster and more secure tendon-to-bone healing.
  
  
  OBJECTIVE
  Placement of tendons in 2 osseous tunnels, as opposed to 1, will enhance tendon fixation as determined biomechanically and histologically.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Fourteen sheep were used, and an extra-articular tendon graft reconstruction was performed on both knees of each sheep. In 1 randomly selected knee, the long digital extensor tendon was released from the femur and placed into a single tunnel in the proximal tibia. In the contralateral knee, the tendon was split and placed into 2 tibial tunnels. Ten sheep were analyzed by mechanical testing, and the remaining 4 were subjected to histologic evaluation at 6 weeks after surgery. Paired t tests were used for statistical analysis.
  
  
  RESULTS
  Mechanical testing demonstrated that the peak load (981.8 +/- 143.2 N, mean +/- SD) and stiffness (570.9 +/- 114.6 N/mm) at 6 weeks after surgery in the double-tunnel group were significantly greater than for the single-tunnel group (714.8 +/- 94.2 N and 432.2 +/- 56.7 N/mm, respectively; load, P = .007; stiffness, P = .03). Histologic analysis suggested similar tendon-to-bone healing for both groups.
  
  
  CONCLUSIONS
  This study demonstrated enhanced biomechanical fixation of the tendon to the surrounding bone in the double-tunnel compared with the single-tunnel technique in this ovine model.
  
  
  CONCLUSIONS
  The double-tunnel technique may provide better fixation and healing in human ligament reconstruction.
authors.affiliation: Comparative Orthopaedic Research Laboratory, Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Drive, Madison, WI 53706, USA. luy@svm.vetmed.wisc.edu
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
authors.forename: Mark D
authors.initials: MD
authors.lastname: Markel
authors.forename: Brett
authors.initials: B
authors.lastname: Nemke
authors.forename: Shawn
authors.initials: S
authors.lastname: Wynn
authors.forename: Ben
authors.initials: B
authors.lastname: Graf
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D005260:Female; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery*; D034561:Sheep, Domestic; D013710:Tendons / Q000637:transplantation*; D053656:Tenodesis / Q000379:methods*; D014945:Wound Healing / Q000502:physiology*