Many different techniques have been developed to repair holes in the chondral (cartilage) surface of the knee joint. There is increasing evidence that the procedure you had on your knee (called autologous chondrocyte implantation or ACI) gives very good overall results. Autologous tells us the graft is taken from the patient him- or herself. A donor sample of chondrocytes comes from a non-weight-bearing section of the knee.
The cells are taken to a lab where they are grown into a larger donor patch of articular cartilage cells. This can take anywhere from four to six weeks. When there are enough lab-grown chondrocytes, the patient comes back in for part two of the surgical procedure.
In this operation, the damaged cartilage is cleaned out and the edges are shaved smooth in preparation for the graft material. The hole is filled in with donor chondrocytes and covered with a special membrane that is stitched in place, sealed, and watertight.
Defects in the osteochondral layer is actually a fairly common problem in active individuals. This type of problem usually develops as a result of trauma. Often there has been a direct blow to the knee. But minor trauma and repetitive motion with a shearing force can also contribute to the development of painful knee problems from osteochondral lesions in younger and younger patients.
Studies have been limited to the results of these treatment approaches in adults. A smaller number of studies have focused on teens between the ages of 14 and 18 years of age. The largest study focusing on teens between the ages of 14 and 18 showed (84 per cent) excellent results.
Eighty-four per cent (84 per cent) had decreased pain and improve motion and function regardless of the size of their lesion (large or small). In other words, patients got better just as often (and just as successfully) with small defects as with large lesions.
One-fourth of the group (about 24 per cent) formed the desired hyaline cartilage. A smaller number of patients (19 per cent) formed a mixture of fibers and hyaline cartilage. Only one patient had a failed result requiring additional surgery.
The authors took a look at some of the other factors to see if any of these affected the final result. For example, they noted that all but one patient had just a single (called isolated osteochondral lesion. But the lesions weren’t all in the same spot of the knees.
There were some lesions located (14) on the medial side (side closest to the other knee) at the end of the femur (thigh bone where it joins to form the knee). Half that number (7) were located on the back of the patella. And another six were found on the lateral side of the femur (side away from the other knee). Results did not appear to be influenced by the location of the knee either.
Interestingly enough, results measured by pain, motion, and function weren’t different (or less positive) when the repaired joint surface turned out to be just fibrous cartilage instead of the real thing. In other words, results were just as good when the repair tissue was not identical to normal hyaline cartilage covering the joint.
The researchers who conducted this study came to the conclusion that autologous chondrocyte implantation (ACI) works well in adolescents with painful osteochondrocyte lesions. This is true even when the final tissue isn’t true hyaline cartilage.
Previous studies support the surgical treatment of painful defects before further joint degeneration occurs. It’s not clear yet if lesions that don’t cause pain should be treated. In time, all the various repair and reconstructive techniques used for osteochondral lesions in adults may be studied in children and teens.