title: Transtibial Tunnel Placement in Posterior Cruciate Ligament Reconstruction: How It Relates to the Anatomic Footprint.
abstract: BACKGROUND
  It is common to place the posterior cruciate ligament (PCL) tibial tunnel with a transtibial technique using a guide that attempts to place the center of the tunnel 1 to 1.5 cm distal to the tibiofemoral joint. It is unknown how well this technique will re-create the native tibial footprint of the PCL.
  
  
  OBJECTIVE
  To evaluate the accuracy of tibial tunnel placement using a transtibial technique.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Ten cadaveric knees from 10 donors underwent arthroscopic transtibial drilling of the tibial tunnel with use of a posteromedial portal for visualization. The transtibial guide was rested flush against the tibial spines to allow for the guide to be as distal as possible, which was between 1 and 1.5 cm distal to the tibiofemoral joint line. Using this technique, an attempt was made to place the tibial tunnels as close to the center of the PCL footprint as possible. All knees underwent computed tomography both pre- and postoperatively with a previously reported technique optimized for ligament evaluation. This allowed comparison of the anatomic PCL tibial footprint to the tibial tunnel aperture. The percentage of tunnel aperture contained within the native footprint as well as the distance from the center of the tunnel aperture to the center of the footprint was measured.
  
  
  RESULTS
  The percentage of tunnel aperture contained within the native footprint was 45.9% ± 23.1%. The distance from the center of the tibial tunnel aperture to the center of the tibial PCL footprint was 6.4 ± 2.3 mm. The tunnels were almost always (9/10) distal (or inferior) to the native footprint and either slightly lateral (5/10) or centered (5/10) in a medial to lateral direction.
  
  
  CONCLUSIONS
  This study demonstrates that using the transtibial drilling technique in the tibia for PCL reconstruction places approximately half of the tibial tunnel aperture within the tibial footprint. Generally, the tunnel is distal to the footprint.
  
  
  CONCLUSIONS
  Consideration should be given to the fact that, using this transtibial technique, the tibial tunnel aperture is generally not placed in the center of the footprint. This may not be a negative issue, however, since there are other potential advantages from distal tunnel placement.
authors.affiliation: Department of Orthopaedic Surgery/TRIA Orthopaedic Center, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Tompkins
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Keller
authors.affiliation: Elite Sports Medicine/Connecticut Children's Medical Center, Hartford, Connecticut, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Milewski
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia, Charlottesville, Virginia, USA. ; Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Cree M
authors.initials: CM
authors.lastname: Gaskin
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Brockmeier
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Hart
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Miller
keywords: PCL reconstruction; tibial footprint; tibial tunnel; transtibial