Chitosan-platelet-rich plasma implants can be injected into meniscus tears to improve repair

摘要

Introduction: Meniscal tears can result from sports or traumatic injuries. Only a small percentage of tears are considered repairable so that current surgical treatment often involves partial meniscectomy which increases the risk for osteoarthritis. New and effective treatment options are needed. Orthopaedic surgeons are currently injecting platelet-rich plasma (PRP) to treat different conditions, but there is conflicting evidence as to whether PRP injections can improve meniscus repair. Chitosan-PRP implants have increased biological activity compared to PRP alone. The purpose of the current study was to investigate if chitosan-PRP implants can improve meniscus repair in the sheep. Materials and Methods: Bilateral 10 mm longitudinal defects were created in the red-white zone in the anterior portion of the medial meniscus in 7 skeletally mature sheep (Fig 1 b). A freeze-dried chitosan formulation containing trehalose and calcium chloride (Fig 1 a) was solubilized with autologous PRP and 0.5 mL of the implant was injected in the tears through two trephination channels, prior to suturing (Fig 1 b). Control tears were injected with 0.5 mL of recalcified PRP. Menisci were assessed at 1 day, 3 weeks and 3 months. Results: Chitosan-PRP implants were partly resident in the tears and trephination channels at 1 day, where they induced cell recruitment from the vascularized periphery of the menisci (Fig 2). A highly cellular and partially integrated repair tissue was seen in one chitosan-PRP tear at 3 weeks (Fig 2). Complete healing with a highly vascularized repair tissue and seamless repair tissue integration was seen in one chitosan-PRP tear at 3 months (Fig 2). There was no repair tissue synthesis in any of the PRP only controls (Fig 2). Discussion: The bilateral tear model did not permit the animal to protect the knees from weight-bearing post-operatively and only a limited volume of the implant could be contained in the longitudinal tears. Even with these limitations, we found that chitosan-PRP implants induced cell migration and repair tissue synthesis in meniscus while PRP alone did not. Improving the residency of the chitosan-PRP implants would be expected to induce a more reproducible healing response. Chitosan-PRP implants have several features that reveal a greater potential than PRP alone to improve meniscus repair. Conclusion: Techniques to adequately repair meniscal tears are currently lacking. Injectable implants composed of freeze-dried chitosan solubilized in autologous PRP have the potential to improve current surgical repair techniques by inducing cell migration, angiogenesis, tissue synthesis and remodeling/integration.