ABSTRACT: Osteochondral defects of the knee are common in orthopaedic patients. They are challenging to treat, especially in young, highly demanding patients who do not qualify for arthroplasty. Among the many possibilities to treat osteochondral lesions presented so far, none is ideal. Because of the poor healing potential of cartilage, treatment outcomes significantly worsen with larger lesions. The treatment of large defects usually requires expensive solutions, sometimes including second-stage surgery. Using mesenchymal stem cell transplantation and cancellous bone autografts, the technique presented here for osteochondral lesion reconstruction can be effectively used to treat large osteochondral lesions in a single-stage procedure. Technique Video Video 1 Osteochondral lesion reconstruction using mesenchymal stem cell transplantation and cancellous bone autografts; right knee. Patients are considered candidates after careful selection. To promote mesenchymal stem cell growth, 4 days before surgery, patients are administered granulocyte colony-stimulating factor. On the day of surgery, the mesenchymal stem cell suspension is obtained, using an MSC blood separator, under the control of the blood bank. A cytometric test is performed for the quantitative evaluation of cell lines, as well as a histopathological evaluation of stained preparations. The cell suspension is then transferred to the operating theater. The diagnosis is confirmed arthroscopically through a standard anterolateral portal, and concomitant lesions are excluded. Mini-open access is created next to the site of the lesion. After the lesion is exposed, delaminated cartilage or bony-cartilage sequestrum is removed. Using a bone spoon, the bony edges of the cavity are resected to healthy cartilaginous tissue. The next step is decortication and debridement of the bottom. To ensure the integration of bone grafts, it is necessary to remove the sclerotic subchondral bone layer until bleeding from the bone occurs. An additional factor improving the blood supply is the microfracturing the bottom of the cavity. From a separate site above the iliac crest, autologous cancellous bone grafts are harvested. The bottom of the lesion is filled with the debris of the cancellous bone. Restoration with a bone graft is performed up to the height of the surrounding healthy bone margin. During this time, the previously sized collagen sponge Tachosil is soaked in MSC suspension. The sponge is placed on the lesion and adjusted to the edges of the lesion using tweezers. The soaked implant should not cover surrounding healthy cartilage edges, but only fill the cavity. The entirety of the damaged fragment is covered with a 2-component fibrin glue. After binding, a suspension of mesenchymal cells, is administered under the fibrin layer using a no. 12 needle, and the application site is sealed with the rest of the glue. The wound is closed with layered sutures and sealed with sterile dressing. The operated joint is protected by cocoon dressing to limit mobility in the early postoperative period.
