Interference screw divergence in femoral tunnel fixation during endoscopic anterior cruciate ligament reconstruction using hamstring grafts.
OBJECTIVE
To compare the divergence angles between bioabsorbable interference screws inserted into the femoral tunnel with the screwdriver placed through the anteromedial portal to those inserted with the screwdriver placed through the tibial tunnel and to examine the effect of the femoral tunnel interference screws' divergence angles on fixation strength of hamstring grafts after anterior cruciate ligament (ACL) reconstruction using hamstring grafts.


METHODS
Cadaveric biomechanical pullout study.


METHODS
ACL reconstruction was performed in 8 pairs of fresh-frozen human cadaveric knees using hamstring grafts fixed within the femoral tunnels using bioabsorbable interference screws. Within matched pairs, 1 screw was placed into the femoral tunnel using a screwdriver placed through the tibial tunnel (group 1), and in the other knee it was placed into the femoral tunnel using a screwdriver placed through the anteromedial portal (group 2). Radiographs were taken to measure the degree of divergence between the interference screw and the femoral tunnel. After disarticulation, pullout strength was then measured using a cyclic-loading model.


RESULTS
In group 2, there was significantly more divergence between the screw and the femoral tunnel compared with group 1, particularly in the sagittal plane (average 14.4 degrees compared with 3.4 degrees, P =.00014). With the number of specimens available for comparison, no significant difference was detected between the 2 groups with regard to 3 mm and 5 mm of pullout when cyclically loaded (P =.77 and.74, respectively).


CONCLUSIONS
The increased technical difficulty, combined with the potential risks of tibial tunnel widening and graft damage, with placement of the screwdriver through the tibial tunnel for the purpose of decreasing femoral interference screw divergence in ACL reconstruction using hamstring grafts may not be justified.
Miller
Christopher M
CM
Kerlan Jobe Orthopaedic Clinic and the Kerlan Jobe Orthopaedic Foundation, Los Angeles, California, USA.
Tibone
James E
JE
Hewitt
Michael
M
Kharrazi
F Daniel
FD
Elattrache
Neal S
NS
D020341:Absorbable Implants; D000368:Aged; D000369:Aged, 80 and over; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001863:Bone Screws; D002102:Cadaver; D004724:Endoscopy / Q000379:methods*; D005269:Femur / Q000601:surgery; D006085:Graft Survival; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D013536:Suture Techniques; D013710:Tendons / Q000637:transplantation*; D013977:Tibia / Q000601:surgery