Femoral bridge stability in double-bundle ACL reconstruction: impact of bridge width and different fixation techniques on the structural properties of the graft/femur complex.
BACKGROUND
The aim of this study was to evaluate the impact of different widths of the bony bridge between the femoral AM and PL bundle tunnel and different fixation techniques on the structural properties of the graft/femur complex in double-bundle ACL reconstructions.


OBJECTIVE
Double-bundle ACL reconstruction with a bony bridge between AM and PL bundle tunnel of 1 mm results in significantly lower structural properties of the graft/femur complex when compared to a bridge of 2 and 3 mm. Interference screw fixation significantly lowers the structural properties when compared to cortical fixation.


METHODS
Controlled laboratory study.


METHODS
Double-bundle ACL reconstructions using different bridge widths (1 mm, 2 mm, and 3 mm bridge) were loaded to failure after a cyclic loading protocol (1,000 cycles 0-200 N) and the structural properties were compared to a single-bundle ACL reconstruction group (n = 10 in each group). The structural properties of using a cortical button fixation were then compared to interference screw fixation (2 mm bridge). Statistical analyses were performed using a Mann-Whitney test (P < 0.05).


RESULTS
Double-bundle reconstructions with cortical button fixation (1, 2, and 3 mm bridge) showed significantly higher ultimate failure loads and stiffness and significantly lower elongation compared to single-bundle reconstructions. Double-bundle ACL reconstructions with a 1 mm bridge showed significantly reduced structural properties of the graft/femur complex compared to a 2 or 3 mm bridge. Aperture fixation led to significantly lower ultimate loads when compared to cortical fixation.


CONCLUSIONS
The bony bridge between the two femoral tunnels in double-bundle ACL reconstructions influences the stability of the graft/femur complex. Aperture fixation using interference screws shows inferior results when compared to cortical fixation.


CONCLUSIONS
The results suggest that the indication for anatomical ACL reconstruction may include the size of the lateral femoral condyle. In small knees, a second femoral tunnel may be difficult to locate with a minimum bridge width of 2 mm.
Department of Trauma-, Hand-, and Reconstructive Surgery, Westfälische Wilhelms-Universität Münster, Waldeyerstr, 1, D-48149, Münster, Germany. a_haas01@uni-muenster.de
Ann-Kristin
AK
Lehmann
Nani
N
Osada
Thore
T
Zantop
Michael J
MJ
Raschke
Wolf
W
Petersen
D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001696:Biomechanical Phenomena; D001863:Bone Screws; D005269:Femur / Q000601:surgery*; D007719:Knee Joint / Q000601:surgery*; D023421:Models, Animal; D019637:Orthopedic Procedures / Q000379:methods*; D013552:Swine; D013710:Tendons / Q000637:transplantation*