This fully arthroscopic procedure, known as autologous chondrocyte implantation (ACI), is a special form of cartilage replacement therapy for the knee and ankle in which the patient's own chondrocytes (cartilage cells) are cultured in a laboratory and then re-implanted in the body. A small sample of cartilage tissue is first removed arthroscopically from a non-load-bearing area of cartilage in the knee and then sent to a special laboratory for isolation and in vitro cultivation.
Arthroscopic Autologous Chondrocyte Implantation (ACI 3D)
While the causes of cartilage defects in the joints may vary widely, all such defects will ultimately lead to pain and increased wear and tear. Unfortunately, these defects do not heal on their own because the body is apparently not able to stimulate cartilage growth and regeneration on its own. The best that can happen as the body attempts to repair itself is the formation of a kind of replacement tissue - also known as fibrocartilage. This replacement tissue, however, lacks the remarkable stability, anti-friction and water-binding properties of the original cartilage.
In certain circumstances, autologous chondrocyte implantation (ACI), in which the patient's own chondrocytes are transplanted into the damaged part of the joint, may represent a very promising form of treatment that enables the patient to avoid early joint replacement surgery.
A distinction is made between standard autologous chondrocyte implantation (ACI) and the more advanced three-dimensional autologous chondrocyte implantation (ACT 3D).
The standard ACI procedure involves removing a piece of the thin tissue covering the shin bone (periosteum) and then suturing it over the injury site so that it serves as a watertight patch. The cultured autologous chondrocytes are then injected into the resulting hollow space.
In the case of autologous 3-dimensional chondrocyte implantation (autologous matrix-induced chondrocyte implantation or ACI 3D for short), 3-dimensional chondrocyte spheres (spheroids) are applied to the injury site without a patch. This procedure is carried out at our clinic through a tiny arthroscopic incision, thereby ensuring maximum protection for the para-articular tissue and significantly reducing the overall surgical risk.
The procedure is carried out in 3 steps:
Step 1: Removal of a sample of cartilage tissue (biopsy)
At our clinic, a sample of the patient's cartilage tissue is removed arthroscopically from a healthy, non-load-bearing area of the joint. Chondrocytes are then isolated from the sample and cultivated in sterile conditions at a highly specialized laboratory for in vitro cell cultivation.
The procedure takes place on an out-patient basis and lasts for around 30 minutes. Around 120 to 150ml of blood is also drawn from the patient. This blood is used in the laboratory for purposes of gaining serum.
Step 2: Production of the autologous three-dimensional chondrocyte implant
The cartilage biopsy - which is roughly the size of a grain of rice - is sent along with the blood sample to the Germany-based co.don® Company, where the chondrocytes are then isolated from the remainder of the tissue sample and cultivated under sterile conditions. The cultivation process is usually completed in about 3 to 4 weeks when small three-dimensional chondrocyte aggregates appear.
This biological material is then sent to the surgeon via express delivery in special refrigerated containers so as to ensure that the quality of the cells is maintained.
Step 3: Surgical Implantation
Surgical implantation is performed at our clinic in the context of a minimally invasive arthroscopic procedure that lasts for around 30 - 60 minutes. The damaged cartilage tissue is first removed from the site in question and then the cultivated, autologous chondrocyte aggregates are implanted. The special cultivation procedure ensures that the cartilage cells adhere to their surroundings.
Once the surgery has been performed, the patient is required to remain hospitalized for a period of around 3 days. The transplanted chondrocytes now trigger a process of regeneration in the joint that leads to the establishment of new cartilage tissue. The new cartilage tissue forms a stable bearing surface as it bonds to the surrounding cartilage.
Patients are usually allowed to begin putting weight on the joint after a resting period of 6 weeks. After three months the joint will have reached a state of full stability and after one year, the implanted cartilage tissue will have achieved the basic structure of the intact surrounding tissue.
