Autologous Chondrocyte Implantation for Knee Cartilage Repair and Regeneration

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• What is Autologous Chondrocyte Implantation?
• ACI Procedure Steps
• Cartilage Cell Cultivation Process
• Indications for ACI Treatment
• Superiority of ACI for Large Defects
• Quality of Regenerated Cartilage
• Full Transcript

What is Autologous Chondrocyte Implantation?

Autologous chondrocyte implantation (ACI) is a advanced surgical technique for knee cartilage repair. Dr. Matthias Steinwachs, MD, describes ACI as a biological approach to restoring damaged knee joints rather than resecting them. This cartilage regeneration method represents a significant shift in orthopedic treatment philosophy. The procedure harnesses the body's own regenerative potential to heal cartilage defects.

ACI Procedure Steps

The ACI procedure involves two separate operations. During the first arthroscopy, surgeons remove small pieces of healthy cartilage from non-weight-bearing areas of the knee. This cartilage biopsy is then sent to a specialized laboratory for processing. In the second operation, the cultivated cells are implanted back into the patient's cartilage defect. Dr. Matthias Steinwachs, MD, emphasizes that these cells are typically seeded onto a collagen scaffold or patch before implantation.

Cartilage Cell Cultivation Process

The laboratory cultivation process is crucial for successful autologous chondrocyte implantation. The process begins with approximately 50,000 cartilage cells extracted from the patient's biopsy. Over a four-week period, these cells multiply under controlled culture conditions. Dr. Matthias Steinwachs, MD, notes that this external cultivation typically yields about 12 million cells. This multiplication process addresses a key biological limitation—cartilage cells within joints cannot naturally multiply on their own.

Indications for ACI Treatment

Autologous chondrocyte implantation is specifically indicated for larger cartilage defects. Dr. Matthias Steinwachs, MD, explains that ACI shows particular effectiveness for lesions measuring between 2 to 8 square centimeters. This size range represents the optimal indication for this cartilage regeneration technique. The treatment is considered for patients whose cartilage damage exceeds what can be effectively treated with simpler arthroscopic techniques.

Superiority of ACI for Large Defects

Clinical studies demonstrate the clear superiority of autologous chondrocyte implantation for larger cartilage lesions. Dr. Matthias Steinwachs, MD, references research comparing ACI with bone marrow stimulation techniques. These studies show minimal outcome differences for smaller defects under 2 square centimeters. However, for larger cartilage defects, ACI consistently produces superior clinical results and better long-term outcomes for patients.

Quality of Regenerated Cartilage

Autologous chondrocyte implantation produces exceptionally high-quality regenerated cartilage tissue. Dr. Matthias Steinwachs, MD, emphasizes that ACI provides some of the best cartilage quality available through current regeneration techniques. The implanted cells on collagen scaffolds gradually form durable, functional cartilage tissue. This regenerated tissue integrates well with surrounding healthy cartilage and withstands normal joint forces following proper rehabilitation.

Full Transcript

Dr. Anton Titov, MD: What is autologous chondrocyte implantation? What are indications for autologous chondrocyte implantation (ACI)? What is the prognosis in patients with knee cartilage defects that were treated with autologous chondrocyte implantation?

Dr. Matthias Steinwachs, MD: I have spent more than 20 years of my career in the field of cartilage tissue regeneration and ACI. I learned that back from the founder in the Göteborg group, Dr. Mats Brittberg. When I initially saw this technique, I was very impressed because it was early treatment.

The first step was that we don't resect a knee joint; we start to restore the knee joint damage. This was, I will say, one of the most impressive points in my life. So in that field, I realized that the knees and cartilage tissues have regeneration potential, and we can support the cartilage regeneration.

For that reason, it was one of the main points in my life, and it's driving me every day. I look for the biology; I try to understand the joints with their biology, with their balance, with their molecules. Independently of meniscus or ligament reconstruction surgery, it is the main aspect of my work.

To go back to your question, the ACI (autologous chondrocyte implantation) is a technique where we remove pieces of cartilage during arthroscopy in an unloaded, non-weight-bearing area of the knee. We send cartilage tissue to a laboratory.

In that laboratory, you remove the cartilage cells out of that cartilage tissue from the patient. Removed cartilage cells are cultivated; cells multiply under culture conditions. So we start the cultivation with 50,000 cells, and after the multiplying process over four weeks, normally you have 12 million cells.

So you can accomplish what the body is not able to do. You enhance the number of cells externally because in the joint, the cells that are embedded in the cartilage are not able to multiply.

In the second operation after cultivation, you implant those cells mostly in combination with a collagen implant. The cells were seeded onto a collagen patch like a scaffold. That collagen patch will be inserted into the cartilage defect.

After some time and defined rehabilitation steps, you will see that implanted cells start to form cartilage of very high quality. So ACI (autologous chondrocyte implantation) provides one of the best cartilage qualities that we can see in cartilage regeneration.

The indication for ACI (autologous chondrocyte implantation) treatment is mostly the bigger cartilage defect lesion. In my answer to the first question, I explained the so-called arthroscopic bone marrow techniques.

These treatment methods are normally for cartilage defect size up to two square centimeters in area. For the ACI (autologous chondrocyte implantation), we see superiority in bigger lesions.

So from two to six or seven, or eight square centimeters, you can use ACI as a very practical and very good technique to restore big cartilage defect lesions. The indication for ACI (autologous chondrocyte implantation) is the bigger defects.

In the studies which compare the marrow stimulation arthroscopic technique with the ACI or ACT, we do not see a huge difference in the outcome of the patient. Only in the bigger lesion do we see superiority of the ACI (autologous chondrocyte implantation) technique.