ACI – Autologous Chondrocyte Implantation

FAQs on Autologous Chondrocyte Implantation (ACI)

 

Autologous chondrocyte implantation (ACI) is an advanced procedure to address cartilage defects in the knee. The cell-based technique approved by the FDA demonstrated its long-term efficacy first during a trial in Sweden in 1987 and was subsequently adopted by the medical fraternity. In the United States and Europe, the method saw its commercial use in the early 2000s and has become popular as the most developed biomedical method to repair damaged cartilage in the last two decades.

What is autologous chondrocyte implantation (ACI)?

Autologous chondrocyte implantation is cell-based, biologic surgical procedure to renovate and restore damaged articular cartilage in the knee. The word autologous means harvesting of cells from a man who is both donor and receiver and chondrocyte refers to healthy cartilage cells. Thus, the entire phrase indicates harvesting of healthy cartilage cells, their cultured growth, and implant on the same person.

The two-stage biomedical technique involves biopsy of the full thickness cartilage defects and then implanting cultured cells to replace damaged ones. ACI is best suited for knee cartilage defects traced to direct, traumatic injury and where healthy cells continue to present in the cartilage.

Autologous chondrocyte implantation ensures pain relief and also reduces the progression to total knee cartilage damage. Patients regain their original knee strength and full range of functions.

Who is a candidate for autologous chondrocyte implantation?

Patients with the following profile are best suited to be treated through autologous chondrocyte implantation.

  • “Clinically significant, symptomatic defects of the femoral condyle caused by acute or repetitive trauma”
  • Those with a focal area of cartilage damage (symptoms joint pain, catching or grinding sensation)
  • No widespread cartilage damage as the case in osteoporosis
  • Suffering from limited activity due to pain or swelling
  • Stable knee and no ligament damage
  • Do not suffer from obesity
  • Tried nonsurgical treatments without significant relief
  • Fitness to undergo post-operative rehabilitation
  • Within 15-65 years age group
  • Not knee damaged enough to require total replacement
  • Patellar cartilage injuries
  • Osteochondral defects

Who is a not a candidate for autologous chondrocyte implantation?

Those with the following conditions are not suitable to have the benefit of autologous chondrocyte implantation procedure.

  • Osteoporosis/ arthritis causing complete cartilage damage
  • Narrowing of joint space or “bone on bone” osteoarthritis
  • Additional knee ligament damage
  • Total knee replacement candidates
  • Rheumatoid arthritis

How does the autologous chondrocytes implantation procedure work?

Autologous chondrocytes implantation follows a two-step procedure. The first step is an arthroscopic procedure to identify and harvest healthy cartilage tissues or chondrocytes, which are cultured and encouraged to multiply in the next 4 to 8 weeks. The second stage is an open surgical procedure. Arthrotomy is performed to implant the cultured healthy chondrocytes in the damaged cartilage area along with a membrane layer.

The preponderance of the new cells injected subdues the damaged ones. New, healthy cells adopt to the new area, grow and eventually replace the older ones. This results in formation of new cartilage. This follows a structured rehabilitation program to restore the joint vitality.

How is autologous chondrocytes implantation performed?

Autologous chondrocytes implantation is performed in three stages. Patient’s own healthy cartilage cells are collected and multiplied using the cell processing method. Finally, doctors implant the cultured into the damaged joint.

  • First Stage: A 30-minute arthroscopic procedure to examine the area of cartilage damage. If the patient is suitable for ACI, a tiny, healthy cartilage piece, between 200 mg and 300 mg, is collected from the non-weight bearing areas.
  • Second Stage: The harvested cartilage part is sent to the laboratory. Chondrocytes are separated from the cartilage piece using Genzyme Tissue Repair methods. These healthy cells are cultured for 4 to 8 weeks prior to implantation using a nutrient rich medium and are multiplied into 5 and 10 million cells.
  • Third Stage: An open incision of 3 to 6 inches long is made and the damaged cartilage area is cleaned. A layer of periosteum or bone-lining tissue is taken from the tibia and “sewn over” the damaged part to create a membrane. Fibrin glue helps close the cover. Doctors inject the newly grown cells underneath the membrane.

How long should I have to wait for implant following arthroscopy?

The time gap is usually 4 to 8 weeks depending on patient’s condition.

How long will it take me to recovery from autologous chondrocytes implantation?

This also differs based on patient condition and the complexity of surgery. In normal cases, it takes about 3 to 4 months of structured rehabilitation and may use continuous passive motion machine to feel improved vitality in the knee joint. However, it is advisable to continue your rehab until a year to completely restore full strength to your knee.

Patients can return to light sports activities after six months and a full return to all types of activities needs at least 9 to 2 months.

What are the advantages of autologous chondrocytes implantation?

  • Best suited to repair pothole-type isolated cartilage defects
  • Patients regain full knee strength and do daily activities with pain
  • Long-term and natural healing solution
  • No fear of implant rejection
  • Highly successful in younger patients debilitating osteoarthritis, disability, and loss of motion
  • Preventative surgery against
  • Shorter surgery times
  • Comparatively low costs.
  • Greater chance of recovery
  • Best method to treat articular cartilage unable to regenerate

How long should I stay in the hospital?

You need to stay in the hospital for the first three nights. However, your stay may be prolongrd if you have complications following autologous chondrocytes implantation.

Do I need rest after autologous chondrocytes implantation?

Yes, you need to have rest for two days, including hospital stay. The knee joint can be moved, first step of the rehab process, only on the third day if you don’t exhibit any complications. There should be no weight bearing until three weeks. You can put heavy pressure on it only after six to eight weeks. It is recommended to wear braces for the first six to eight weeks.

What are complications of autologous chondrocytes implantation?

There is no fear of implant rejection as chondrocytes are harvested from patients’ own body. However, surgical procedure-linked complications may surface unless it is done by experts. Rare side effects include secondary surgeries due to diagnosis of graft overgrowth or failure, arthrofibrosis, and joint adhesions.

When can I go back to work? When can I resume my regular activity?

Recovery is subject to patient condition. Most return o their work in six to eight weeks. But for labour intensive works, your should wait until 12 weeks after the autologous chondrocytes implantation. Avoid high-impact activities for almost a year, though you can do bike riding or walking after four months.

How well does autologous chondrocytes implantation work?

Autologous chondrocytes implantation is 85% effective in treating cartilage defects in the knee. It is best for younger patients with damaged area over 2 cm in diameter. The regenerated cartilage and careful rehabilitation assures 90% restoration of the original strength.

References

Jones DG, Peterson L. “Autologous chondrocyte implantation” Instr Course Lect. 2007;56:429-45.

Giuseppe Filardo, et al: Arthroscopic Second-Generation Autologous Chondrocyte Implantation-A Prospective 7-Year Follow-up Study. Am J Sports Med October 2011 vol. 39 no. 10 2153-2160

Joshua D. Harris, MD, et al. Autologous Chondrocyte Implantation. A Systematic Review. In The Journal of Bone and Joint Surgery. September 15, 2010. Vol. 92-A. No. 12. Pp. 2220-2233.

Konst, Y. E., et al (2012). Treatment of severe osteochondral defects of the knee by combined autologous bone grafting and autologous chondrocyte implantation using fibrin gel. Knee Surgery, Sports Traumatology, Arthroscopy, 20 (11), 2263-2269.

Zaslav, K., et al. (2009). A prospective study of autologous chondrocyte implantation in patients with failed prior treatment for articular cartilage defect of the knee: Results of the Study of the Treatment of Articular Repair (STAR) clinical trial. American Journal of Sports Medicine, 37 (1), 42-55. (Level 2 Evidence – Independent)

Knutsen G, et al (March 2004). “Autologous chondrocyte implantation compared with microfracture in the knee. A randomized trial”. J Bone Joint Surg Am 86–A (3): 455–64.

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