Autologous Chondrocyte Implantation

What is Autologous chondrocyte implantation?

Autologous chondrocyte implantation (ACI) is a moderately new procedure that is used to treat disconnected full-thickness (down to the bone) articular cartilage defects of the knee. ACI has also been performed to correct abnormalities of the patella (knee top) along with different joints of the body.

Who is the Candidate for ACI?

People who are possible candidates for ACI have a region of damaged cartilage on their knees. The pain and swelling, or swelling that restricts their movement impels them to seek this surgery.

Symptoms

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 joints 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.

Causes

Direct blow – if a joint receives a heavy impact, perhaps during a bad fall or an automobile accident, the cartilage may get damaged. Sports people have a higher risk of suffering from articular damage, especially those involved in high impact sports like football, rugby, etc.

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 are 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 is the ACI Conducted?

ACI is a two-step procedure, which is as follows:

STEP 1:
Knee Arthroscopy for cartilage harvest

In this arthroscopy procedure the cartilage plug is harvested from non weight bearing zone of the femur bone. The cartilage sample is sent to a laboratory, where the cells are separated and refined for 3– 5 weeks to acquire an adequate number of cells (somewhere in the range of 5 and 10 million cells).

STEP 2:
Implantation of chondrocyte cells

In this stage, the knee is opened and the defect is measured. The margins are freshened and the bone bed is curetted, till fresh subchondral bone is visualised. Microfracture drill holes are made on the bed. Now the defect site is ready and can be injected with autologous chondrocyte cells very slowly from the outer border to the center. Once the implantation is set, the knee can be sutured and a sterile dressing is applied.

Post-Operative Care

Post-op of ACI, 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 are concentrated on immobile quadriceps and hamstring exercises to maintain muscle bulk.