Graft Remodeling and Joint Degeneration after ACL Reconstruction in the Growing Knee Joint - PROJECT SUMMARY Anterior cruciate ligament (ACL) injuries impact more than 250,000 people in the U.S. annually. The fastest rising injury rates are in children and adolescents with significant growth remaining. Reconstruction of a completely torn ACL is becoming increasingly popular to treat these injuries in children of all ages to restore knee stability and permit the return to sports while limiting secondary injuries to other structures. Failure rates after ACLR for pediatric patients are higher than adults, with similar risk for long-term joint degeneration. For complete injuries, a variety of techniques have been proposed, including epiphyseal, complete transphyseal, and partial transphyseal approaches. Yet, comparisons of long-term joint degeneration between techniques have not been performed. For partial ACL injuries, increasingly, surgeons will reconstruct the ACL; however, it is unclear if outcomes are better by replacing the ACL entirely or by preserving the functional bundle. Human pediatric joints for in-vitro cadaveric testing are extremely limited, and animal models are often skeletally mature. To better assess surgical techniques for skeletally immature patients, it is necessary to use a model that accounts for age- specific ACL function as well as match the biomechanical properties of the allograft to the native ACL. The porcine model is useful to study the ACL during growth and established the age-dependent nature of ACL bundle function. Thus, the objective of this proposal is to better understand outcomes after complete and partial ACL reconstruction during growth and use this knowledge for selection of appropriate surgical techniques. To accomplish this objective, we will leverage our multi-disciplinary experience to accomplish the following aims. In Aim 1, we will determine how ACLR technique influences the ability to restore joint stability and reduce joint degeneration at different stages of skeletal maturity. In Aim 2, we will determine how the location of partial ACL injury (anteromedial (AM) or posterolateral (PL)) influences the ability of partial or complete ACL reconstruction to restore joint stability and reduce joint degeneration. Successful completion of these aims will guide surgical technique section after complete and partial ACL injuries in children and adolescents.
