Information for patients
Naturally regenerate cartilage
Our joints are critical to our mobility. The knee joint in particular works extremely hard every day and is one of the most important pillars of our mobility. Articulating joints such as the knee can only function effectively and without pain thanks to the cartilage between the joint surfaces. If this essential cartilage in the knee or another joint is damaged, it can cause us pain and significantly reduce our quality of life.
How does cartilage damage occur?
Cartilage defects are usually caused by twisting of the knee, which also damages other joint-stabilising structures. Underlying bone pathologies such as osteochondritis dissecans can also damage the protective cartilage surface. If left untreated, early-stage damage progresses to a more painful and functionally debilitating inflammatory osteoarthritis condition.
Naturally regenerate cartilage – with your body’s own cells
Healthy cartilage tissue, also known as hyaline cartilage, has exceptional shock-absorbing and frictionless properties that allow smooth, pain-free joint movement. It is a pressure-resistant, highly elastic tissue that consists of 80% water and a very small volume of cartilage cells known as chondrocytes.
Chondrocytes form a network of crosslinked collagen fibres and specialized proteoglycans that attract and bind water. This combination forms an elastic tissue that protects the joint against pressure. Viewed under the microscope, cartilage tissue is a three-dimensional structure made up of collagen and proteoglycans interspersed with chondrocyte cells.
Cartilage defect diagnosis and therapy
If you suspect a cartilage defect, your doctor can use imaging techniques, such as MRI, to make a reliable diagnosis and to determine the precise extent of the damage. When it comes to cartilage damage, an ounce of prevention is generally worth a pound of cure: Clinical studies have shown that osteoarthritis risk increases dramatically with larger cartilage defects that are not treated promptly or correctly.
What procedures are available?
Non-surgical forms of therapy – such as targeted physiotherapy, pain relief with ibuprofen or acetaminophen, injections of corticosteroids or viscosupplements such as hyaluronic acid – may temporarily relieve pain and restore function. Once these conservative approaches start to fail, surgical treatment is the only option.
Today there are several surgical procedures available – ask your doctor which of these options is the right one for you.
Microfracture surgery can be considered for small cartilage damage up to 2 cm2 in size. The bone underneath the cartilage defect is perforated using special drills or chisels, allowing blood from the bone marrow to enter the defect area and coagulate there. This stimulates the formation of a blood clot. Stem cells within the clot form a fibrous repair tissue that does not have the same pressure resistance and elastic properties as healthy hyaline cartilage.
This procedure describes microfracture surgery in which the defect is additionally covered with a biomaterial, usually a collagen matrix. This helps anchor the blood clot within the defect and reduces the risk of shearing or loosening of the clot. However, as with microfracture surgery without biomaterial, usually only fibrous cartilage is generated.
This method transfers healthy bone cartilage plugs from non-weight-bearing regions of your joint to your damaged cartilage area. The method, also known as mosaicplasty, can be used for minor cartilage damage. It is generally no longer recommended for defects larger than 2 cm2, as the use of several punch cylinder biopsies results in an incongruent (non-matching) surface in the treated defect area, which significantly increases the resulting risk of osteoarthrosis.
Modern transplant procedures, such as autologous chondrocyte transplantation (ACT), offer the possibility of regenerating cartilage damage using cartilage cells from your own body. A solution of chondrocytes harvested and grown in culture from a small sample of your own cartilage tissue is placed into the cartilage defect and kept in place with a water-tight membrane. These procedures are minimally invasive, joint-preserving and offer patients many other advantages.
Cartilage cells (chondrocytes) from the knee: These specialized cells are responsible for maintaining the smooth, protective cartilage that cushions and supports the joints, enabling pain-free movement.
Cartilage regeneration
Cartilage can’t regenerate itself because mature cartilage has no blood supply and very few chondrocytes available to repair the damage. The repair tissue that does form in some cases serves more as a short-term scar tissue that does not have the shock-absorbing, frictionless properties of healthy hyaline cartilage.
Natural cartilage regeneration
Biological cartilage reconstruction procedures, such as matrix-associated autologous chondrocyte transplantation (MACT), use intelligent biomaterials to produce an individualized cell graft using your own cartilage cells that are then transplanted into the defect. This approach is recommended by the German Society for Orthopaedics and Trauma Surgery (DGOU) as a standard treatment for cartilage defects since 2004.[2]
The DGOU's recommendations in 2022 speak of treating small defects, from 2 cm².[1][1]
TETEC is the European leader in MACT, with more than 28,000 individual products manufactured for the biological reconstruction of cartilage damage in various joints.. Our next-generation, injectable gel-based MACT is a minimally invasive, outpatient procedure that significantly simplifies the implantation surgery and also supports the natural regeneration of new and healthy cartilage tissue.
Clinical outcomes
High success rate for knee cartilage defects with MACT
The results of long-term studies[1] and prospective randomised studies show the TETEC approach is significantly superior to other methods of treating cartilage defects exceeding 4 cm2 in size. Success rates of over 90% were reported in studies over a period of 14 years.[2]
Patients with limited degenerative cartilage damage can also benefit from this approach: Initial clinical studies show good outcomes in such cases.[3][4]
How MACT Works
MACT is performed in three steps.
Biopsy
During diagnostic arthroscopy, small cartilage-bone cylinders are taken from a non-weight-bearing part of the joint.
Cultivation
At TETEC, the chondrocytes from this biopsy are isolated, multiplied in vitro, and applied to a three-dimensional collagen matrix.
Transplantation
The matrix can then be transplanted into the cartilage defect in a second procedure.
When is MACT used?
Chondrocyte implantation is generally suitable for the surgical biological reconstruction of full-thickness cartilage damage in the knee joint. In addition to the size of the defect and the condition of the cartilage, other individual factors play an important role. Which therapy is the right one for a knee cartilage defect is also determined by factors such as biological age, lifestyle and body weight.
Your specialist will determine whether and under what conditions MACT is right for you following a thorough examination. The effects of the individual factors must be assessed by the orthopaedist treating you.
MACT follow-up treatment
What do you need to consider after treatment with the MACT procedure?
Post-operative follow-up after cartilage cell implantation depends primarily on the anatomical location of the cartilage defect within the knee joint. The cartilage must first heal completely in this position in order to be able to optimally perform its task as a shock absorber for the joint again. Gradual muscular stabilization of the joint is extremely important and can take a long time.
Since everyone reacts differently to a surgical procedure, the follow-up treatment program can vary from patient to patient. In general, follow-up treatment will call for bed rest in the first few days after the operation, generally avoiding loading the knee joint by using walking aids and accompanying physiotherapy over the next few weeks. Your doctor will work out the appropriate measures for you after the operation.
Follow-up assessments
To ensure the long-term success of cartilage regeneration, follow-up checks are recommended at regular intervals. In addition to the clinical follow-up assessment, an MRI examination three and 12 months after implantation is suggested, in line with recommendations by medical associations.
Are you interested in chondrocyte implantation?
Find qualified centres near you offering MACT with TETEC technologies.
[1] Angele P, Zellner J, Schröter S, Flechtenmacher J, Fritz J, Niemeyer P. Biological Reconstruction of Localized Full-Thickness Cartilage Defects of the Knee: A Systematic Review of Level 1 Studies with a Minimum Follow-Up of 5 Years. Cartilage. 2022 Dec;13(4):5-18. DOI: 10.1177/19476035221129571
[2] Eichinger M, Henninger B, Petry B, Schuster P, Herbst E, Wagner M, Rosenberger R, Mayr R. Treatment of cartilage defects in the patellofemoral joint with matrix-associated autologous chondrocyte implantation effectively improves pain, function, and radiological outcomes after 5-7 years. Arch Orthop Trauma Surg. 2024 Apr;144(4):1655-1665. DOI: 10.1007/s00402-023-05179-0
[3] Weishorn J, Wiegand J, Zietzschmann S, Koch KA, Rehnitz C, Renkawitz T, Walker T, Bangert Y. Factors Influencing Long-term Outcomes After Matrix-Induced Autologous Chondrocyte Implantation: Long-term Results at 10 Years. Am J Sports Med. 2024 Sep;52(11):2782-2791.DOI: 10.1177/03635465241270152
[4] Niemeyer P, Albrecht D, Andereya S, Angele P, et al. Autologous chondrocyte implantation (ACI) for cartilage defects of the knee: A guideline by the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Trauma (DGOU), The Knee, Review 23,426-435(2016). DOI: 10.1016/j.knee.2016.02.001