Two-stage late reconstruction with a fresh large osteochondral shell allograft transplantation (FLOCSAT) for a large ostechondral defect in a non-union after a lateral tibia plateau fracture 2-year follow up.

This is the description of a 58-year-old female patient presenting 8 months after a horse riding accident with significant pain and inability to walk independently. Imaging revealed a large osseous defect of the lateral tibia plateau which was not united posteriorly. The patient refused knee replacement and we developed a patient specific two-step procedure for her. Step 1: Filling of the defect with a large cortico-cancellous autograft from the posterior iliac crest; step 2: Transplantation of a fresh large osteochondral shell allograft (FLOCSAT). The postoperative protocol included continuous passive motion (CPM), partial weight bearing for three months, and physiotherapy. Based on the concept of immuno-privileged cartilage tissue, the patient did not get any immuno-suppressive therapy. Pain-, activity of daily living, Lysholm and Tegner scores were evaluated before defect filling surgery with autograft, before allograft transplantation, and at 12 and 24 months after allograft transplantation. There were no complications. Radiographic analyses with plain films and CT scans revealed solid osseous integration within 3 month. The patient regained excellent functionality in both, activities of daily living and sports (back to horse riding, trampolin jumping). Knee arthroscopy after 1year showed excellent condition of the lateral meniscus and the cartilage of the lateral tibia plateau. Chimerism/DNA analysis of a cartilage biopsy showed, that at 1year 32% of the donor cells have been already replaced by the patient's own cells. To our knowledge, this is the first case of a patient who sustained such a large defect during a tibia plateau fracture, and got successfully treated with a fresh large osteochondral shell allograft transplantation in a two-step procedure.