Biomechanical analysis of a double-bundle posterior cruciate ligament reconstruction

The objective of this study was to experimentally evaluate a single-bundle versus a double-bundle posterior cruciate ligament reconstruction by compar ing the resulting knee biomechanics with those of the intact knee. Ten huma n cadaveric knees were tested using a robotic/universal force-moment sensor testing system. The knees were subjected to a 134-N posterior tibial load at five flexion angles. Three knee conditions were tested: 1) intact knee, 2) single-bundle reconstruction, and 3) double-bundle reconstruction. Poste rior tibial translation of the intact knee ranged from 4.9 +/- 2.7 mm at 90 degrees to 7.2 +/- 1.5 mm at full extension. After the single-bundle recon struction, posterior tibial translation increased to 7.3 +/- 3.9 mm and 9.2 +/- 2.8 mm at 90 degrees and full extension, respectively, while the corre sponding in situ forces in the graft were up to 44 +/- 19 N lower than thos e in the intact ligament. Conversely, with double-bundle reconstruction, th e posterior tibial translation did not differ significantly from the intact knee at any flexion angle tested. This reconstruction also restored in sit u forces more closely than did the single-bundle reconstruction. These data suggest that a double-bundle posterior cruciate ligament reconstruction ca n more closely restore the biomechanics of the intact knee than can the sin gle-bundle reconstruction throughout the range of knee flexion.