Biomechanical Comparison of Quadriceps and Patellar Tendon Grafts in Anterior Cruciate Ligament Reconstruction.

Purpose: To quantify the structural and material properties of 10-mm central sections of the quadriceps and patellar tendons in the setting of anterior cruciate ligament reconstruction using cadaveric grafts and biomechanical analysis.

Methods: The structural and mechanical properties of 11 bone-patellar tendon-bone (BPTB) and 12 quadriceps tendon-bone (QT) allografts were evaluated. Ten-millimeter-wide tendon grafts from both patellar and quadriceps tendons were harvested and subjected to biomechanical testing using the MTS servohydraulic test machine (MTS Systems, Eden Prairie, MN). The cross-sectional area was also calculated and compared between the BPTB and QT grafts.

Results: The mean cross-sectional area was 91.2 ± 10 mm(2) for the QT compared with 48.4 ± 8 mm(2) for the BPTB (P = .005). The mean ultimate stress was 23.9 ± 7.4 MPa for the QT and 33.4 ± 9.0 MPa for the BPTB (P = .01). Ultimate strain was similar between the 2 tested groups, with a 10.7% change in the QT group and an 11.4% change in the BPTB group (P = .484). The Young modulus of elasticity was 255.3 ± 64.1 MPa for the QT and 337.8. ± 67.7 MPa for the BPTB (P = .006). The mean stiffness was 466.2 ± 133 N/mm for the QT and 278.0 ± 75 N/mm for the BPTB (P = .005). The mean ultimate load to failure was 2,185.9 ± 758.8 N for the QT compared with 1,580.6 ± 479.4 N for the BPTB (P = .045).

Conclusions: The cross-sectional area of the QT was nearly twice that of the BPTB. Ultimate load to failure and stiffness were also significantly higher for the QT graft. The variability in the cross-sectional area was similar in both tendon groups.

Clinical Relevance: On the basis of graft predictability and biomechanical properties, our study reaffirms that the QT graft is a biomechanically sound alternative for anterior cruciate ligament reconstruction.