Bone marrow stimulation techniques are used to treat a knee with a hole or defect in the articular cartilage. Articular cartilage is the rubbery, fibrous cartilage that covers the ends of bones to protect the joint. When the defect goes all the way down to the first layer of bone, it’s called a full-thickness defect.
There are different ways to stimulate the bone marrow to produce new chondrocytes (cartilage cells). Drilling into the first layer of bone under the articular cartilage is one. Shaving the surface of the bone called abrasion arthroplasty is another and microfracture is the third method currently in use.
If one of these methods doesn’t work, the surgeon can try another of the three approaches in hopes of a better outcome. Or you might be a good candidate for another treatment method called autologous chondrocyte implantation (ACI).
With ACI, normal, healthy cartilage cells (chondrocytes) are removed from a part of the knee joint that is not weight-bearing. They are taken to a lab where they are multiplied to form enough repair cells to put back in the defect and stimulate growth of the needed fibrocartilage. The cultured chondrocytes are injected underneath a special patch that has been placed over the hole.
However, it is important to know that there is some evidence that ACI after having a bone marrow stimulation treatment has a higher rate of failure. In fact the failure rate was three times higher in patients who had ACI after a failed bone stimulation surgery. Failure meant the patient still had pain limiting function, MRIs showing that the graft didn’t take, and/or surgery had to be done to remove the graft.
It’s not clear yet just what caused that high of a failure rate. At first, the scientists thought it was because patients developed thickening of the subchondral (first layer of bone under the cartilage), bony overgrowth, and/or the formation of subchondral cysts. They seemed more likely to have a poor outcome when this happened.
Deterioration and failure of the bone marrow stimulation may occur because the new tissue forms over a thick, protruding, and stiff subchondral base. Eventually that subchondral plate starts to degenerate.
But it’s also possible there are some patient-specific (unknown biologic) reasons for this failure that had nothing to do with having autologous chondrocyte implantation AFTER marrow stimulation surgery.
It may be best if you make a follow-up appointment with your surgeon to find out what’s next for you. Any of these procedures might be possible and highly effective. You don’t have to accept painful suffering without exploring a few other ideas first.