Mechanical Properties of Quadriceps Tendon Allograft Compared to Bone- Patellar Tendon-Bone Allograft as an Alternative Graft for ACL Reconstruction

Introduction: Over 200,000 anterior cruciate ligament reconstructions (ACLR) are performed in the United States yearly, making it one of the most common orthopedic procedures. Graft choices for ACLR include both autograft and allograft tendons. The most popular autograft choices are the bone-patellar tendon-bone (BPTB) and hamstring (HS) tendons. While the BPTB has long been considered “the gold standard” of autograft choices, the operative time for harvest and harvest site morbidity present significant problems. The HS graft also presents issues with post operative numbness, weakness and the inability to reliably predict the size of the graft pre-operatively. The BPTB is also a popular allograft choice, but its availability and intraoperative length restrictions again make its use problematic. Thus, alternative autografts and allografts grafts are being considered. Recent improvements in both graft harvest and operative fixation have renewed interest in the quadriceps tendon as both an autograft and allograft choice. Thus, biomechanical comparisons of the patella tendon and quadriceps tendon grafts (QTG) are important as a means to select the best ACL replacement graft. Previous studies evaluating the graft biomechanical characteristics have yielded conflicting results and failed to consider both structural and material properties when testing the quadriceps tendon. Our hypothesis is that the quadriceps tendon will have biomechanical properties equivalent or better than the bone-patellar tendon-bone graft thus providing a suitable alternative graft choice for ACL reconstruction. In this study, in-vitro mechanical testing was performed to quantify both the structural and material properties of 10 mm sections of the quadriceps and patellar tendon.