Surgeons in Sweden began performing cartilage repair procedures called autologous chondrocyte implantation (ACI) back in 1987. More than 20 years have passed since then. That's time enough to check back and see how things have gone and what kind of results have been achieved. Patients who had this procedure were asked two basic questions: 1) Are you better, same, or worse? and 2) If you had it to do over again, would you have this surgery?

What exactly is the procedure? Autologous chondrocyte implantation (ACI) involves the use of normal, healthy cartilage cells to fill in a hole (defect or lesion) in the joint surface of the knee. The defect goes clear down to the bone below the cartilage. It's called a full-thickness cartilage and osteochondral lesion. Osteochondral refers to bone (osteo) and cartilage (chondral).

Autologous chondrocyte implantation is done in two separate steps. First, the surgeon removes the harvested cartilage cells from an area of the knee that doesn't bear weight. They are taken to a lab where the cells are multiplied until they have enough to fill in and cover over the defect.

A second surgery is done to implant the new healthy cells. If there are any alignment problems or other soft tissue injuries, surgery is done before implantation to correct them. The corrective surgery is a necessary step in order to protect the implanted area. If there are uneven forces within the joint, the load imbalance can reinjure the same spot all over again.

At the University of Gothenburg in Sweden, 341 patients have had the autologous chondrocyte implantation (ACI) procedure. Through a series of mailings, 224 of those patients provided the authors with some feedback on the long-term results of their ACI. Besides answering the two main questions, they reported on pain and other symptoms, activity level, and quality of life.

With any surgical procedure and especially fairly new ones, there are always patients who don't have the best results. In this group, about one-fourth reported being worse instead of better. But of the remaining majority (three-fourths of the group), 92 per cent said that they would have the surgery again. They reported good results that lasted and were satisfied with the results.

When the researchers took a closer look at the patients and the results, they couldn't see any kind of link between age and outcomes. And it didn't seem to matter what size the defect was -- the results were equally good for small to large lesions. They did a second analysis comparing results based on the type of lesion repaired.

For example, some patients had the defect on the femoral side of the joint. Most of the lesions were on the medial side of the femur (side closest to the other knee) but there were some on the lateral side (side away from the other knee). Ninety per cent of this group said they would do the operation again because it was so successful in eliminating their pain and restoring the use of their knees.

Some patients had more than one defect in more than one place. Patients with multiple lesions of this type had slightly worse results than single lesions. Patients with bipolar lesions (present on both medial and lateral sides) seemed to have the worst results.

Full-thickness osteochondral lesions of the patella (knee cap) were more complicated to treat effectively. The authors suggested this might be because there were more bony malformations and muscle imbalances to work through compared with patients with femoral lesions.

Patients treated for osteochondral lesions caused by osteochondritis dissecans (OCD) reported the best results. With OCD, the joint surface is damaged and doesn't heal well. The problem occurs where the cartilage of the knee attaches to the bone underneath. The area of bone just under the cartilage surface is injured, leading to damage to the blood vessels of the bone. Without blood flow, the area of damaged bone actually dies.

This condition can affect adults and children. It's the younger patients who still had the best results. That may be because they have the ability to heal faster and better than older adults. They are still able to participate in all kinds of physical activities because arthritis hasn't developed yet.

The authors conclude there is still much to be studied and decided about autologous chondrocyte implantation. Even though they have 20 or more years of information, the ACI procedure that was done in 1987 isn't the same as what's done now. So, in the coming years, comparisons between first-generation and subsequent generations will have to be made.

Most of the patients in the study were young athletes, so the effect of aging over time will also have to be examined. Likewise, most of the patients did have other injuries of the meniscus or the ligaments. Treatment results will be compared between patients with and without other injuries. Another area that will bear watching and comparing is the group of patients who had realignment procedures to correct deformities and malalignment problems.

The new second- and third-generation autologous chondrocyte implantation (ACI) procedures will be watched carefully in the next 10 to 20 years. But for now, it's clear that the first-generation methods were successful and durable (long-lasting).
Reference:

Reference: Lars Peterson, MD, PhD, et al. Autologous Chondrocyte Implantation. A Long-term Follow-up. In The American Journal of Sports Medicine. June 2010. Vol. 38. No. 6. Pp. 1117-1124.