The Rectus Femoris Tendon as a Graft for Combined ACL and Anterolateral Reconstruction: A Biomechanical Evaluation

Background: The rectus femoris (RF) tendon may be an option for combined anterior cruciate ligament (ACL) and anterolateral (AL) reconstruction utilizing a double-stranded (DRF) tendon for the ACL and a single-stranded tendon (SRF) for AL reinforcement; however, biomechanical data remain limited. Purpose/Hypothesis: This study aimed to biomechanically assess the DRF for ACL reconstruction using a patellar tendon (PT) graft and the SRF for AL reconstruction using an iliotibial band (ITB) graft. The hypothesis was that the biomechanical properties of the DRF graft would not differ from those of the PT graft, and the SRF graft would not differ from the ITB graft. Study Design: Controlled laboratory study. Method: Eight fresh-frozen human knees were used: 2 male and 6 female, with a mean age of 49 years (range, 36-64 years). Each knee produced 4 grafts: DRF, SRF, PT, and ITB. Each graft was mounted in a materials test machine. The cross-sectional area was measured using alginate molding. After 10 preconditioning cycles to 250 N, each specimen was extended to failure at 100 mm/min. The Friedman test assessed differences between the 4 graft types using matched samples. The Dunn multiple-comparison test was used to examine differences among graft types. Results: The ultimate strengths (N) of the grafts were as follows: DRF, 1978 ± 338; SRF, 1445 ± 584; PT, 1824 ± 557; ITB, 819 ± 268 (DRF and PT >ITB; P < .01). The elastic moduli (MPa) were as follows: DRF, 272 ± 59; SRF, 617 ± 153; PT, 318 ± 90; ITB, 631 ±4 31 (DRF and PT<SRF; P < .05). The ultimate tensile stresses (MPa) were as follows: DRF, 51 ± 12; SRF, 89 ± 28; PT, 62 ± 19; ITB, 56 ± 24 (SRF > DRF; P < .05). Conclusion: As hypothesized, the DRF graft exhibits mechanical properties that do not differ from those of the PT graft. Likewise, the SRF graft showed biomechanical properties that do not differ from those of the ITB graft. Therefore, this study supports the use of the RF graft for combined ACL and AL (anterolateral ligament or lateral extra-articular tenodesis) reconstruction. Clinical Relevance: The RF tendon graft is harvested before being merged with other layers, resulting in a longer graft (mean, 273 mm) suitable for folding. This does not create a full-thickness defect through the quadriceps. This approach allows combined ACL + AL reconstruction techniques and additional graft tissue for fixation.