Autologous Chondrocyte Implantation (ACI)

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Autologous chondrocyte implantation (ACI) is a relatively new, state-of-the-art procedure used to treat isolated full-thickness (down to bone) articular cartilage defects of the knee. It has been approved by … Read More

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Autologous Chondrocyte Implantation (ACI)

Autologous chondrocyte implantation (ACI) is a relatively new, state-of-the-art procedure used to treat isolated full-thickness (down to the bone) articular cartilage defects of the knee. It has been approved by the Food and Drug Administration for cartilage defects located at the end of the femur bone (thigh). ACI has also been performed for defects of the patella (knee cap) in addition to other joints of the body. Autologous chondrocyte implantation is a two-stage operative procedure. Autologous Chondrocyte Implantation, ACI, is the collection of articular cartilage cells (chondrocytes), which are multiplied in a laboratory to increase the cell number and then re-implanted with a special surgical technique into the damaged part of the knee. This allows cell growth and cartilage repair to take place, producing new and durable cartilage. Is most suitable for the treatment of cartilage damage caused by direct injury; for instance, sports injuries, car accidents, and falls, where the injured part is surrounded by normal healthy cartilage. 

Preparation for an autologous chondrocyte implantation

Before carrying out autologous chondrocyte implantation, a thorough clinical assessment of the joint must be carried out. After which the patient will undergo plain X-rays and an MRI scan of the knee to help make an accurate assessment of the location and the size of the cartilage defect. A range of motion brace will also be organized prior to the procedure to restrict the joint movement and protect the cartilage graft. Food and drinks will also be avoided from midnight before your surgery until the surgery has been completed.

Autologous chondrocyte implantation procedure.

The autologous chondrocyte implantation procedure is in two stages;  First Autologous Chondrocyte Implantation Procedure The initial arthroscopy for the biopsy is carried out as a day surgery procedure.
  • Biopsy of Articular Cartilage: The first operation involves collecting a small biopsy of the articular cartilage, which is processed in a tissue engineering machine. 
  • Cell Culture: The biopsy is then processed, to release the chondrocytes (that is, articular cartilage cells) from the articular cartilage. The released cells are placed in a rich nutrient medium and incubated to cultivate cell growth. The culture process and incubation continue until an optimal and desired cell number is attained. The duration of this varies, depending on lesion size, but it normally ranges between 3 to 4 weeks. 
Second Autologous Chondrocyte Implantation Procedure  Implantation of Cells  The second operation is carried out to convey the newly generated cells into the damaged part. This procedure is usually performed under general anesthesia, supplemented with a femoral nerve block to help with post-operative pain. This is achieved by sealing the injured area with a waterproof cover and injecting the cells beneath the cover into this area. The cells attach themselves to the bone and then begin the process of regenerating the articular cartilage matrix.  This procedure takes roughly 2 hours. After which the leg is placed in a knee immobilizer and relaxed for 24 hours; to reduce the risk of patch disruption and enable the cells to begin the formation of cartilage matrix. To ensure proper protection of the implanted cells, a hospital stay is required for a number of days to allow progressive joint mobilization.  During this period, walking will be aided with crutches and a straight-leg splint touching the operated foot to the ground without putting weight on the leg. The brace must be worn day and night, and can only be removed when doing the knee curl exercises and for showering.  Results of Autologous Chondrocyte Implantation Studies carried out internationally show that the use of cartilage culture and implantation bring significant improvement in about 85% of patients, with many being able to return to full, normal pain-free activities.

Post-Operative Care

Post-op of autologous chondrocyte implantation, a knee brace will be necessary for a period of 3 months. Also, the patient’s weight-bearing on the knee is restricted for the first 6 weeks. Physiotherapy will also commence immediately, but the range of motion is determined by the exact size and location of the cartilage defect. Early physiotherapy sessions is concentrated on immobile quadriceps and hamstring exercises to maintain muscle bulk.


Patients with damage to the cartilage in a joint (articular cartilage damage) will experience:

  • Inflammation – the area swells, becomes warmer than other parts of the body, and is tender, sore, and painful.
  • Stiffness.
  • Range limitation – as the damage progresses, the affected limb will not move so freely and easily.

Articular cartilage damage most commonly occurs in the knee, but the elbow, wrist, ankle, shoulder, and hip joint can also be affected.
In severe cases, a piece of cartilage can break off, and the joint can become locked. This can lead to hemarthrosis (bleeding in the joint); the area may become blotchy and have a bruised appearance.


  • Direct blow – if a joint receives a heavy impact, perhaps during a bad fall or an automobile accident, the cartilage may be damaged. Sportspeople have a higher risk of suffering from articular damage, especially those involved in high impact sports like American football, rugby, and wrestling.
  • Wear and tear – a joint that experiences a long period of stress can become damaged. Obese individuals are more likely to damage their knee over a 20-year period than a person of normal weight, simply because the body is under a much higher degree of physical stress. Inflammation, breakdown, and eventual loss of cartilage in the joints is known as osteoarthritis.
  • Lack of movement – the joints need to move regularly to remain healthy. Long periods of inactivity or immobility increase the risk of damage to the cartilage.


How long will the treatment last?
Findings of studies show that autologous chondrocyte implantation lasts for at least 10 to 20 years, with very good recovery both on an objective and scientific level, and also as regards to how patients feel and manage their daily activities.

What are the advantages of autologous chondrocyte implantation?
The chief advantage of autologous chondrocyte implantation is that it is the first means of treatment to be developed that gets close to achieving cartilage regeneration; creating an almost identical tissue of the original, as opposed to simply repairing the tissue, which usually results in the fibrous cartilage.

What are the disadvantages of autologous chondrocyte implantation?
Autologous chondrocyte implantation is an expensive procedure to execute. The benefits of this procedure is yet to be fully understood.
Maturation of tissue takes as much as 9–12 months.

What are the complications of autologous chondrocyte implantation?
Some of the complications of autologous chondrocyte implantation include; Delamination, Poor integration with the subchondral bone, Adhesions, Periosteal cover hypertrophy (1st generation).

What is articulate cartilage?
Articular cartilage is the steady, even coverage on the ends of bones where they make contact with other bones to form an articulating joint such as seen in the knee.