Anterior Cruciate Ligament Reconstruction With a Porcine Xenograft: A Serologic, Histologic, and Biomechanical Study in Primates

Purpose: This study proposes treatment methods to provide a mechanically competent, immunocompatible, and sterile porcine graft for human knee ligament reconstruction. Methods: The anterior cruciate ligament (ACL) was reconstructed by using treated porcine patellar tendon grafts or controls of untreated porcine grafts or allografts in 20 rhesus monkeys. Animals were stratified into 2-, 6-, and 12-month postreconstruction cohorts. Serologic and histologic assessments were performed to evaluate host immunological and cellular response. Healing and functional integrity of the ACL reconstructions were assessed by tensile biomechanical testing. Results: Untreated porcine grafts were acutely resorbed and rejected, whereas treated porcine grafts and allografts were incorporated by the host as functional grafts. Temporal histologic assessment of treated porcine grafts and rhesus grafts revealed gradual host cellular infiltration and graft collagen remodeling through a similar mechanism of ligamentization. Biomechanical evaluations support graft functional integration with no difference between allograft and treated graft reconstructions. Conclusion: Rhesus allograft and treated porcine grafts presented with similar healing profiles in a long-term evaluation of ACL reconstruction. Clinical Relevance: Immunochemical modification and sterilization of porcine patellar tendon grafts may improve initial biocompatibility and long-term functionality of xenografts in musculoskeletal applications.