Evaluation of the single-incision arthroscopic technique for anterior cruciate ligament replacement. A study of tibial tunnel placement, intraoperative graft tension, and stability.

The tension in an anterior cruciate ligament graft may not be normal when the femoral tunnel is placed using the single-incision arthroscopic technique because the femoral tunnel is drilled through the tibial tunnel. We hypothesized that the in vivo tensile behavior of the double-looped semitendinosus and gracilis tendon graft can be normal or abnormal compared with the native anterior cruciate ligament, that the placement and angle of the tibial tunnel can predict the tensile behavior of the graft, that the graft with abnormal tensile behavior is associated with a nonanatomically placed tibial tunnel, and that the tensile behavior of the graft determines the stability of the reconstructed knee at 1 year. Total tension in the graft and knee flexion angle were measured in 14 subjects as the knee was flexed from 0 degree to 90 degrees. A graft force greater than 40 N at 80 degrees of flexion was considered abnormal. One year after surgery, the angle and position of the tibial tunnel were determined from roentgenograms, and knee stability was measured with a KT-1000 arthrometer. The criteria for anatomic tibial tunnel placement in the sagittal and coronal planes were derived from magnetic resonance images of uninjured knees. The tensile graft behavior was either normal (4 of 14) or abnormal (10 of 14) with the single-incision arthroscopic technique. The angle of the tibial tunnel in the coronal plane was predictive of abnormal tensile behavior. Abnormal tensile behavior occurred in anatomically placed tibial tunnels and was compatible with a stable and functional reconstructed knee at 1 year.