Scientists have found ways to get a healing response in joint cartilage, but nothing really restores the cartilage back to normal. One way to foster healing is to take normal, healthy cartilage cells from one area of the joint and transfer them to the damaged section. This has been done successfully in the knee and more recently, also in the ankle. The procedure is called an autologous chondrocyte implantation (ACI).
The sandwich procedure is used when the surgeon performs an ACI. Patients selected for this treatment have defects in the joint cartilage that go clear down to the bone. They have had extensive nonoperative treatment as well as at least one failed surgical procedure.
The sandwich procedure was recently developed by a group of surgeons to use along with an ACI in the ankle. They call it a modified ACI procedure. First, the ACI graft is done. Healthy cartilage is harvested from the knee and transplanted to the defect. Once that’s in place, then the surgeon sews a covering over the healing site. The covering is called a periosteal flap. This is the first piece of bread in the sandwich procedure. A special fibrin glue is injected between the flap and the bone graft. This is done to seal off the bone marrow cavity from the joint.
The surgeon puts the second piece of bread in the sandwich right on top of the first. This is done by placing one more layer of bone on top of the first periosteal flap. This layer consists of another periosteal flap, this time turned so the outer bone layer is facing the first periosteal flap. The second flap is also sewn in place, but the surgeon leaves a tiny opening at one end.
Once the second flap is sutured in place, then fibrin glue is used to form a tight seal around the sutures. They do a water test to make sure there are no areas of leakage. At this point, the filling is placed between the two pieces of bread. In other words, the harvested chondrocytes are injected between the two layers of bone graft (i.e., between the two periosteal flaps). The surgeon injects the transplanted chondrocytes into the tiny hole left open when the second periosteal flap was sutured.
It’s good to have an understanding of the different techniques used to repair deep cartilage defects. But this isn’t a commonly used procedure. It may not be one your surgeon performs. Having done your homework, you’ll have a better idea what to ask your surgeon when you do go in for your consult.