PURPOSE

To evaluate the effect of posterolateral bundle (PLB) graft fixation angles on graft tension curves and load sharing between the anteromedial bundle (AMB) and the PLB in double-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Twenty-four patients who underwent double-bundle ACL reconstruction were included in this study. AMB and PLB were provisionally fixed to a graft tensioning system during surgery. The graft fixation settings were as follows: (1) AMB at 20° and PLB at 0° (A20P0), (2) AMB at 20° and PLB at 20° (A20P20), and (3) AMB at 20° and PLB at 45° (A20P45). Bundle tension was recorded during knee flexion-extension and in response to anterior or rotatory loads. A pivot-shift test, as well as factors affecting the residual pivot-shift, was also evaluated.

RESULTS

A20P45 created reciprocal tension curves and load sharing, in which the tension in both bundles was equivalent during flexion-extension and during each loading test at 30°. In A20P0, the tension of the AMB was constantly higher than that of the PLB. Seven patients showed grade 1 pivot-shift phenomenon in A20P0, whereas no patient showed a positive pivot-shift at other settings. Larger tension reduction of the PLB between 0° and 30° and smaller load sharing of the PLB were significant factors affecting residual pivot-shift.

CONCLUSIONS

In double-bundle ACL reconstruction, fixation of the AMB at 20° and the PLB at 45° created reciprocal tension curves and load sharing between the bundles. Fixation of the AMB at 20° and the PLB at 0° led to insufficient tension in the PLB, resulting in a residual pivot-shift phenomenon in 7 of 24 patients.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.