Purpose: Quadriceps tendon grafts have renewed interest for ACL reconstruction; however, biomechanical studies comparing anatomic single-bundle (SB) and double-bundle (DB) reconstruction techniques are rare. The purpose of this study was to compare the knee biomechanics in four different types of anatomic ACL reconstruction techniques, using the quadriceps tendon in a human cadaver.
Methods: Four different tibial (T) and femoral (F) tunnel configurations, (a) DB-2F-2T, (b) DB-2F-1T, (c) SB-1F-1T and (d) DB-1F-2T, were used for ACL reconstruction using the split quadriceps tendon with patella bone. Ten cadaver knees were subjected to an 89 N anterior tibial load and combined 7 N m valgus and 5 N m internal torques. The anterior tibial translation (ATT) and in situ force were measured using a robotic system for the ACL-intact, ACL-deficient and ACL-reconstructed knees.
Results: DB reconstructions mostly restored ATT to the intact ACL. The in situ forces under the anterior load in the DB reconstructions were similar to the intact ACL, but that of the SB reconstruction was different at 30°, 60° and 90° of flexion (P < 0.05). Under combined torques, the in situ force of the SB graft was less than that of intact ACL at 0°, 15° and 30° of knee flexion (P < 0.05), while that of the ACL DB reconstruction was similar to the intact ACL.
Conclusion: DB ACL reconstruction using quadriceps tendon can restore biomechanics of the knee to that of the intact ACL regardless of whether three or four tunnels are used, but SB reconstruction does not.