Comparison of 2 femoral tunnel locations in anatomic single-bundle anterior cruciate ligament reconstruction: a biomechanical study.
OBJECTIVE
To evaluate knee stability after anterior cruciate ligament (ACL) reconstruction using 2 modern clinically relevant single-bundle constructs.


METHODS
Two arthroscopic ACL reconstructions were performed on 6 fresh-frozen human cadaveric knees using bone-patellar tendon-bone autografts. The tibial tunnel was centered in the anatomic tibial footprint. The femoral tunnel was reamed through the anteromedial (AM) portal and centered alternately in either the AM portion of the femoral footprint (center-AM) or the center of the femoral footprint (center-center). Two external loading conditions were applied: (1) a 134-N anterior tibial load and (2) a 10-Nm valgus load combined with a 5-Nm internal tibial torque. Resulting kinematics were determined under 4 conditions: (1) ACL intact, (2) ACL deficient, (3) center-AM reconstruction, and (4) center-center reconstruction.


RESULTS
In response to anterior tibial loading, anterior translation was similar in the ACL-intact knee and the 2 reconstructions at 0° to 60° of flexion but was greater in the reconstructed specimens at 90°. In response to the complex rotatory load, internal tibial rotation (ITR) at 30° of flexion was slightly greater in center-AM knees compared with ACL-intact knees (11.0° ± 0.6° v 10.5° ± 0.6°, P = .03). At other angles tested, ITR in both reconstructions was similar to the ACL-intact knee (P > .05). When we compared the 2 reconstruction alternatives, however, center-center knees exhibited greater resistance to ITR at all angles (P < .05).


CONCLUSIONS
Anatomic single-bundle ACL reconstruction performed with the femoral tunnel placed through the AM portal restores translational and rotational knee stability to an extent that closely approximates the ACL-intact condition. When compared with the AM femoral tunnel position, a femoral tunnel positioned in the anatomic center of the femoral origin of the ACL may further improve rotatory stability without sacrificing anterior stability.


CONCLUSIONS
This study provides additional biomechanical evidence in support of anatomic single-bundle ACL reconstruction with tunnels positioned in the center of the femoral and tibial footprints.
Scott and White Memorial Hospital, Temple, Texas 76508, USA. mdriscoll@swmail.sw.org
Matthew D
MD
Driscoll
Gene P
GP
Isabell
Michael A
MA
Conditt
Sabir K
SK
Ismaily
Daniel C
DC
Jupiter
Philip C
PC
Noble
Walter R
WR
Lowe
D000328:Adult; D000368:Aged; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001696:Biomechanical Phenomena; D050376:Bone-Patellar Tendon-Bone Grafting; D002102:Cadaver; D005269:Femur / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007593:Joint Instability / Q000601:surgery; D007719:Knee Joint / Q000503:physiopathology*; D008875:Middle Aged; D012399:Rotation; D013977:Tibia / Q000503:physiopathology / Q000601:surgery