Dr. med. Alfred Tylla is a highly respected and exceptionally qualified specialist in knee surgery, renowned for his outstanding expertise in joint preservation, sports orthopedics, and complex reconstructive procedures. As the head of the Knee Center certified by Rummelsberg Hospital, he has been dedicated for many years to providing the best possible care to patients in the greater Nuremberg area. He places particular emphasis on preserving natural cartilage and treating meniscus, ligament, and cartilage damage with gentle methods, in order to maintain knee health over the long term.
His expertise is evident not only in modern, scientifically based care but also in his extensive experience with minimally invasive techniques such as arthroscopy. With gentle keyhole procedures, he diagnoses and treats cartilage, meniscus, and cruciate ligament injuries at an international level. Thanks to his comprehensive qualifications in trauma surgery, visceral surgery, and innovative surgical methods, he is a sought-after expert in the treatment of both acute injuries and chronic conditions.
The Knee Center at Rummelsberg Hospital, certified by the German Knee Society since 2019, enjoys an excellent reputation in the region. Patients here benefit from treatment that performs more than 900 highly complex procedures each year and adheres to the highest quality standards. Dr. Tylla is active not only in daily clinical practice but also engages in international research and scientific work.
As a member of renowned professional societies, he regularly publishes innovative research findings and stays at the forefront of the latest developments in knee surgery. In addition to his work in the operating room, Dr. Tylla also serves as an emergency specialist and in traumatology. His rapid diagnostic capabilities and precise treatment decisions in emergencies ensure that injuries are managed quickly and professionally. For many patients with knee problems, modern cartilage replacement therapy offers a promising option. The editorial team of the Leading Medicine Guide had the opportunity to learn more about this in a conversation with Dr. Tylla.
Cartilage replacement therapy offers modern and innovative approaches to restore or replace the body’s natural cartilage in the joint. With advanced techniques, it is now possible to sustainably regenerate damaged or worn cartilage, relieve pain, and maintain mobility in the long term. These therapeutic options are particularly suitable for patients who already show the first signs of osteoarthritis and wish to preserve their joint function.
Cartilage degeneration can occur in some individuals for various reasons, with multiple factors often playing a role.
“Cartilage wear essentially arises from different causes. In many cases, traumatic consequences are responsible—accidents or injuries that lead to an acute change in the cartilage surface. Such damage often results from pressure or impact that directly injures the cartilage. Degenerative processes also play a major role, meaning age-related wear and tear, often exacerbated by axis misalignments or previous surgeries, such as after a meniscus injury.
Another important factor is so-called functional instabilities, which can also damage the cartilage. These are patients who have often suffered muscle atrophy, whether due to lack of training, aging, or degenerative processes, which reduce joint stability. This decreased stability allows the joint to make micro-movements, similar to sandpaper, which in turn can wear down the cartilage. Excessive movement can also be harmful to cartilage, though this largely depends on the stability of the joint.
If the joint is well supported by strong muscles and stable ligaments, movement generally does not cause harm—especially when the cartilage is well trained and healthy. The situation becomes more difficult if, suddenly—for example after an injury or in an unstable joint condition—excessive movement is permitted. When stability is lacking, even high activity can damage cartilage, as dysfunction may lead to microtears or wear,” explains Dr. Tylla regarding the causes of cartilage damage.
Today, several methods of cartilage replacement therapy are available, tailored to the type, size, and location of the cartilage defect as well as to each patient’s specific characteristics. These procedures differ in their mechanisms of action, the materials used, and their respective applications, but the ultimate goal is always to restore the natural cartilage in the joint as permanently as possible, while improving mobility and quality of life for patients.
“There are now many different cartilage replacement procedures, applied depending on the size and location of the defect. One of the best-known is the so-called OATS procedure (OATS = osteochondral autologous transplantation), in which cartilage and bone cells are taken from non-weight-bearing areas of the patient’s own joint and transplanted into the defect zone. This method is particularly suitable for small defects, as a patient’s own cartilage-bone tissue can be used without requiring foreign material.
In younger patients, regenerative approaches are also applied. Here, small drill holes are made in the defect to mobilize stem cells from deeper layers, which can then transform into cartilage cells or cartilage-like tissue structures. To keep the stem cells in place, a membrane is sometimes applied, as in the AMIC procedure—autologous matrix-induced chondrogenesis. This technique ensures that blood and stem cells diffusing into the area remain there to form cartilage. Similarly, biological collagen—a gel-like substance—can be injected directly into the cleaned defect, although this method is only useful for smaller lesions,” Dr. Tylla explains further.
“For larger defects, techniques such as autologous matrix-induced chondrocyte transplantation (MACT) are used. In this method, cartilage tissue is harvested from the patient, and the cells are cultivated in the laboratory before being implanted back into the defect about three weeks later. This procedure is usually staged, meaning it is performed in two operations. For smaller defects, cartilage fragments can also be minced and re-implanted in a single procedure, a method known as Minced Cartilage.
The process usually begins with arthroscopy to assess the defect. After a detailed consultation with the surgeon, the most suitable method is chosen together with the patient. The decision depends primarily on the location and size of the defect. During the second operation, about three weeks later, the actual transplantation is performed. This procedure typically lasts only 30 to 45 minutes. After surgery, patients can usually move freely right away, although for defects in certain areas, partial weight-bearing of about 25 kilograms is required for the first four to six weeks. During this period, crutches support mobility and recovery.”
Copyright: Dr. med. Alfred Tylla
In practice, the choice of the optimal procedure always depends on the individual situation of the patient. Factors such as age, activity level, size and location of the defect, joint health, and prior treatments play a decisive role. The goal is to create long-lasting, resilient cartilage that largely restores the natural function of the joint and significantly reduces osteoarthritis-related symptoms. Advances in material research, cell technology, and minimally invasive procedures promise continuous improvement in treatment outcomes and open up new long-term perspectives for patients to live pain-free and active lives.
Although there is currently no perfect artificial cartilage available on the market, scientists are intensively researching innovative solutions.
“A truly market-ready artificial cartilage identical to natural tissue does not yet exist. Various approaches are available, such as collagen membranes or collagen-based fluids—for example, in the AMIC procedure, where collagen from porcine material is used. However, these materials do not represent a true one-to-one cartilage replacement but serve more as supportive substances. There are also approaches in which cartilage is cultivated from the body’s own tissues—for example, from nasal cartilage or other tissue sources—so it can later be re-implanted.
Currently, numerous studies are underway in which such cultivated tissue is already being applied to patients, but there is still a lack of long-term data. It remains unclear whether these methods will deliver sustainable benefits over 15 or 20 years. The problem is that patients should not be subjected to procedures where the long-term outcomes remain uncertain. However, researchers hope that future studies will provide meaningful results on the long-term success of these approaches,” notes Dr. Tylla.
It also happens that patients delay treatment and only seek medical attention at an advanced stage, when cartilage replacement therapy is no longer a reasonable option.
“In our consultations, we always conduct a special deformity analysis in advance, where we carefully discuss the risks. A thorough medical history is particularly important to determine whether the patient is suitable for this procedure at all. A successful treatment strongly depends on patient compliance—meaning the ability to consistently follow rehabilitation measures, weight-bearing instructions, and aftercare steps. If compliance cannot be ensured, the chances of success decrease, which is why strict patient selection is necessary.
Before surgery, we also always inform patients that intraoperative findings may ultimately determine whether they are true candidates for the procedure. If, during the operation, we discover that osteoarthritis is already too advanced or the cartilage defect is larger than initially assumed—something MRI results do not always reflect accurately—we may adapt the procedure on the spot or switch to alternative treatment methods. This ensures that only those patients are treated who actually have a high chance of success.”
Cartilage replacement therapy is particularly suitable for patients with localized, stable cartilage damage that impairs normal joint function and has so far not been sufficiently improved by conservative treatments. This includes primarily younger and middle-aged patients who do not yet suffer from advanced osteoarthritis in the affected joint, as their joints still have good residual function and regenerative capacity. In particular, individuals whose cartilage-related complaints can be traced to a clearly defined defect in the articular cartilage benefit from targeted reconstruction.
On this, Dr. Tylla comments: “Borderline cases in cartilage replacement therapies are especially seen when multiple defects in the joint are present and come into contact, a situation referred to as ‘kissing lesions.’ This occurs when damaged areas on the femur and tibia meet—especially when both areas have severe defects. In such cases, patients are generally not suitable for cartilage replacement therapy such as MACT (matrix-induced autologous chondrocyte transplantation).
Similarly, this treatment is not an option in advanced osteoarthritis where the entire joint is severely affected. For successful therapy, the defect size should generally not exceed 10 to 11 square centimeters. For patients who have just begun walking again after surgery, noticeable improvements typically start after a few weeks. The initial pain caused by the surgery itself should decrease significantly in the long term.
However, postoperative loading pain often persists, as the surgical access to the joint can still be painful. Especially during passive mobilization—patients are often discharged with a motorized splint—early signs of improvement can be observed. The ultimate goal is for the patient to completely overcome wound pain, regain full pain-free weight-bearing capacity, and move the joint freely,” and Dr. Tylla adds specific notes for highly active individuals:
“In young, athletically active patients—such as tennis players—the so-called ‘return to sports’ usually occurs between three and six months after surgery. Caution is required during this period, as localized pressure loads, rapid changes of direction, and stop-and-go sports such as tennis or squash can stress the newly created cartilage zone. Particularly when the original damage was caused by leg malalignment, such as bow legs or knock-knees, or by instability, these underlying conditions must first be corrected. Only when the biomechanical prerequisites are in place can cartilage surgery be sustainably successful. The actual cartilage therapy is more of a ‘cherry on top,’ used to optimize the basic biomechanics and thus achieve lasting results.”
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Copyright: Dr. med. Alfred Tylla.
The long-term results of cartilage replacement therapy are overall very promising, with many patients experiencing stable improvements in joint function and significant pain reduction for at least five to ten years. In optimally selected patients and with professionally performed procedures, the reparative cartilage cells or substitute materials can be preserved permanently, allowing the joint to largely maintain its function while significantly reducing discomfort. There are cases where positive effects were still evident more than ten years after treatment, highlighting the durability of modern methods.
Nevertheless, the sustainability of outcomes varies individually and depends on a wide range of factors. One of the most important is patient selection: particularly in younger, active patients up to their mid-50s who do not yet have advanced osteoarthritis or extensive joint destruction, the prognosis for long-term stabilization and function preservation is especially good.
“An important piece of advice is always to consult physicians who follow a holistic concept and have extensive treatment experience. There are certainly specialized doctors who should be evaluated carefully, since the challenges with such therapies are significant. A crucial criterion is that the physician considers the entire knee joint as well as the overall condition of the patient, rather than viewing cartilage replacement therapy in isolation. It is essential to always remember that behind every knee is a person.
This means not only looking at images such as X-rays or MRIs, but treating the patient as a whole. The doctor should be able to provide comprehensive counseling and emphasize that a successful outcome depends largely on patient compliance. Muscle strengthening and conditioning play a central role—whether aiming for cartilage transplantation, ligament reconstruction, or a prosthesis. My advice to patients and colleagues is: if you want to do something for your knee, the top priority should always be muscle. Strong, stable muscles create the best conditions for long-term success and ensure the joint remains healthy even after treatment,” explains Dr. Tylla, adding:
“Regarding demand, I notice that more and more patients are coming to us, as we have built up a high level of expertise in cartilage replacement therapy. Especially in recent years, the number of affected patients has increased. At the same time, I observe that muscle strength in many patients is declining. Many hope that surgery will be a cure-all and believe all problems will be solved afterwards. However, this is a misconception. Success depends largely on the patient’s cooperation and willingness to actively participate in rehabilitation and muscle building.
Without targeted training, physiotherapy, and consistent joint care, even the best surgery will not deliver lasting success. Ultimately, it is the patient’s commitment that determines the outcome—not just the physician’s technique. For example, if an older patient still has stable muscles and no other significant health issues, they may well be suitable for treatment. My ‘oldest’ patient who underwent cartilage replacement therapy was 64 years old.”
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Copyright: Dr. med. Alfred Tylla
Currently, cartilage replacement therapy is in many cases covered by health insurance. Since 2007, such procedures have generally been reimbursable benefits. Particularly with more complex techniques such as MACT, coverage by insurers has so far been common, though how long this will remain the case strongly depends on the current healthcare policy environment.
Cartilage replacement therapy is considered a relatively safe treatment option, yet—as with all surgical and regenerative procedures—certain risks and possible complications must be taken into account.
“In principle, cartilage replacement therapy carries the usual surgical risks such as infections, pain, postoperative bleeding, or hematomas. In addition, inflammatory changes in the joint may occur. However, for cartilage there is a specific risk worth mentioning: in the worst case, the implantation of the graft may fail because the body rejects the transplanted cartilage tissue. This can happen if biological integration does not succeed, particularly at the transition zone between cartilage and bone. If the biological conditions are not optimal or accompanying joint structures are not adequately addressed, the risk of failure increases. Fortunately, with careful patient selection and consideration of all relevant factors, the chances of success are very high,” says Dr. Tylla.
Copyright: Dr. med. Alfred Tylla
The Knee Center at Rummelsberg Hospital has been successfully re-certified and holds a recognized quality accreditation. The certification confirms the high level of expertise and the excellent treatment options in reconstructive and endoprosthetic knee surgery. Regular re-certifications ensure that standards remain up to date and are continuously improved.
“Our team is now very well established, as we have been re-certified as a German Knee Center and have four certified knee surgeons on staff. This is quite extraordinary, as most hospitals have only one such specialist. With growing expertise, we have also increased the number of surgical procedures: today we perform almost 900 reconstructive knee surgeries per year. The professional quality and experience within the team are therefore very high.
In terms of development and technology, I see progress today as less urgent. In the early years, there were higher hopes for innovative drugs or injections that might improve processes in the knee. Nowadays, my main concern is that colleagues should place patients more at the center of treatment again. It happens frequently that patients who come into a clinic are immediately recommended a knee prosthesis, without considering alternative options. This is also due to the way the healthcare system structures reimbursement: payment for reconstructive surgery is relatively low compared to the much more lucrative endoprostheses, which often makes prosthetic replacement the first choice. Yet, many patients could keep their natural knee for years with good reconstructive surgery, avoiding the need for a prosthesis.
Unfortunately, this issue is discussed far too rarely today, as the impression arises that the financially more attractive prostheses dominate treatment. The current political and financial framework in healthcare makes planning difficult. Many hospitals are currently uncertain about the future because final decisions are still pending. The postponement and deferral of important questions create uncertainty in financial planning, making it challenging to plan for the coming years. Nevertheless, I see a major problem in the fact that ultimately, it is the patient who suffers,” emphasizes Dr. Tylla, making it clear at the conclusion of our conversation:
“Despite all the burdens and uncertainties in the system, one must not forget: it is the patient who suffers when economic or political decisions are carried out at their expense. Many colleagues and patients report that it has become increasingly difficult to get timely appointments. Access to specialists and treatment is a growing challenge, which significantly complicates care. My main wish is to put people back at the center of medicine. Therapies should primarily serve the individual goals of the patient, rather than being driven exclusively by financial interests.”
Dr. Tylla – thank you very much for your valuable insights!
