Table 3.

Step-by-Step Technique of Cartilage Repair in Knee Using Umbilical Cord WJ-MSCs Embedded Onto Collagen Scaffolding and Implanted Under Dry Arthroscopy

1. Place the freezing bag containing the WJ-MSC suspension in a 37°C water bath 30 minutes before the expected time of surgical implantation.

2. When thawed, transfer the WJ-MSC suspension into a sterile conical tube containing 50 mL of saline solution and centrifuge at 300g for 7 minutes at 22°C.

3. Remove the supernatant from the tube, and resuspend the pellet of cells in a second sterile tube containing 50 mL and repeat centrifugation.

4. Remove the supernatant, and suspend the WJ-MSC pellet in 1 mL of saline solution and transfer it to a sterile syringe to create the final suspension of cells that is cleared of DMSO.

5. Position the patient as for standard knee arthroscopy and administer general or spinal anesthesia.

6. Examine the knee with the patient under anesthesia to confirm or identify associated pathology.

7. Perform diagnostic arthroscopy and identify any coexisting conditions that require treatment.

8. Visualize cartilage lesions in their entirety to ensure adequate access for arthroscopic treatment. Traction sutures or specialized soft-tissue retraction instruments may increase the working space and improve visualization.

9. Treat associated pathology and perform appropriate osteotomy as indicated.

10. Prepare the cartilage lesions by removing unstable or loose tissue, and prepare vertical cartilage walls about the periphery to create a well-shouldered lesion using ring curettes or Chondrectomes.

11. Remove the calcified cartilage layer at the base of the defect without significant damage to the subchondral plate.

12. Use an arthroscopic measuring tool to determine the dimensions of the defect and create a size-matched template using a sterile dental dam or aluminum foil. Insert the template into the defect, and modify the size as needed to accurately re-create the dimensions of the defect.

13. Use the template to perform appropriate size matching of a bilayer type I/III collagen scaffold to the defect. Mark the scaffold surface composed of densely compacted collagen to ensure the porous layer will be appropriately placed against the subchondral bone at the time of graft insertion.

14. Moisten the collagen scaffold with saline solution, and immerse this into the suspension of WJ-MSCs for a period of 5 min.

15. Drain fluid from the articular space, and place a skid or valveless cannula through the working portal in preparation for dry arthroscopy.

16. Confirm complete visualization of the prepared cartilage defects, and reassess adequate access to the entire base and periphery.

17. Gently insert the WJ-MSC–embedded scaffold into the relevant knee compartment through the valveless cannula using a specialized graft inserter, grasper, or nontoothed forceps. Place the porous layer of the scaffold against the subchondral plate, with the marked layer visible and facing outward.

18. Press fit the WJ-MSC–embedded scaffold graft into the defect. Apply fibrin glue to the periphery of the graft to improve stability of fixation.

19. Cycle the knee under arthroscopic visualization to confirm stability of the implanted graft.

20. Close the surgical wounds appropriately, apply a dressing, and place the brace into a knee brace locked in extension.

DMSO, dimethylsulfoxide; WJ-MSC, Wharton's jelly–derived mesenchymal stem cell.