The Knee Surgeon

Autologous Chondrocyte Implantation

Autologous Chondrocyte Implantation (ACI) is an advanced surgical procedure used to treat larger articular cartilage defects in joints. It aims to repair the damaged cartilage by introducing healthy cartilage cells from the patient’s own body. ACI is particularly suitable for larger defects that are not effectively treated by simpler methods like microfracture.

  1. In the first step, a small piece of healthy cartilage is harvested from a non-weight-bearing area of the patient’s joint during an initial arthroscopic surgery.
  2. The harvested cartilage tissue is sent to a laboratory, where the cartilage cells (chondrocytes) are isolated and cultured. This process typically takes a few weeks.
  3. Nowadays however there are companies that offer an one stage procedure where the cells are cultured in theatres by a specialist.
  4. Once a sufficient number of cartilage cells are cultured, the patient undergoes a second surgery. During this procedure, a small incision is made over the site of the cartilage defect.
  5. The damaged area of the joint is carefully prepared by removing any damaged or unhealthy tissue. which may make the defect larger than initially thought or seen in the investigations .
  6. The underlying bone is also cleaned and prepared to create a suitable environment for the implanted cells.
  7. The cultured cartilage cells are then implanted into the prepared defect site. Sometimes, a specialized scaffold or matrix may be used to hold the cells in place and provide structural support as they integrate into the joint.
  8. The incision is closed, and the joint is allowed to heal. Patients will typically undergo a rehabilitation program, including physical therapy, to gradually regain strength, mobility, and function.

ACI offers several advantages over other techniques for cartilage repair:

  • ACI results in the regeneration of hyaline-like cartilage, which closely resembles the original cartilage in the joint and offers better long-term durability compared to fibrocartilage formed through techniques like microfracture.
  • ACI is effective for larger defects that may not respond well to less invasive procedures.
  • Successful ACI can lead to improved joint function and reduced pain over the long term.

However, there are also some potential limitations and considerations with ACI:

  • ACI involves two surgeries, which can extend the overall treatment timeline and recovery period but see note above for one stage procedure.

The need to culture cells in a laboratory can increase costs and the time required before the second surgery.

  • ACI is often more suitable for younger patients with healthy bone marrow, as older patients may have fewer viable cartilage cells.