Holes referred to as “defects” in cartilage and bone such as you had can be treated with the technique you described: osteochondral autograft transfer or OAT. Osteochondral lesions refer to damage or defects to the joint cartilage (chondral) that go all the way down to the first layers of bone (osteo).
Holes in the osteochondral layer and/or loose fragments of bone and cartilage in the joint can cause pain, locking of the joint, and eventually osteoarthritis. To help prevent this from happening, treatment can be done with osteochondral autograft transfer (OAT).
OAT involves removing a plug of cartilage and bone from a healthy area (in this case from a non-weight bearing area of the knee) and transferring it into the osteochondral lesion (i.e., hole in the surface of the your ankle bone). The word “autograft” refers to the fact that you donate your own tissue for the procedure.
Efforts are being made to identify factors that might predict a good or favorable result. Surgeons might suggest using a second arthroscopic examination to evaluate the results of this procedure. Because it is an added expense and an invasive procedure, it is rare that a second-look arthroscopic exam is recommended. But quality of bone and cartilage graft evaluated using the second arthroscopy instead of X-rays or more advanced imaging like MRIs gives a much a better look at the actual results. The surgeon can see exactly how well the graft has taken, how much bone is growing, and any problems that might be developing.
A second-look arthroscopy does provide an opportunity to treat any problems present, especially mismatching of the joint surfaces. Fibrous adhesions causing impingement can be removed. And any uneven margins can be smoothed over. Any gaps where the graft meets the defect can be filled in.