Dr. Matthias Pothmann is a highly qualified specialist in Orthopedic Surgery and Sports Medicine. As head physician of the Westphalian Joint and Endoprosthetics Center at the Christliches Klinikum Unna, he specializes in hip and knee joint replacement surgery. In treating joint osteoarthritis, especially in cases of complex deformities (particularly hip dysplasia), he combines the most advanced minimally invasive techniques with exceptional expertise, which has earned him an outstanding reputation in the field.
His clinic is not only renowned for hip and knee joint replacements, but also for the high standard of joint-preserving procedures, such as corrective pelvic surgeries (triple osteotomies) and hip surgeries performed by the clinic’s senior attending physician, Dr. Axel Küpper. By specifically using minimally invasive techniques, Dr. Pothmann and his team ensure that muscles and surrounding tissue are subjected to minimal stress, which leads to faster recovery and a lower risk of postoperative complications.
The clinic is among those in Germany with the lowest complication and infection rates following joint replacement and prosthesis revision surgeries. These methods and results have established the Westphalian Joint and Endoprosthetics Center as one of the leading hubs for hip arthroplasty and even as a German reference center for minimally invasive hip replacement for several prosthesis manufacturers. In addition to his successful work in joint replacement, Dr. Pothmann is also highly skilled in complex revision surgeries. When artificial joints lose their function, specialized procedures may be necessary to restore mobility. This requires not only technical expertise but also extensive experience with bone grafts and reconstructive bone surgery.
Of particular importance is Dr. Pothmann’s personal approach, which is based on a patient-centered philosophy. For him, the individual treatment approach takes priority – he consistently strives to provide every patient with the most gentle, tailored, and effective therapy possible. With his extensive expertise and personal commitment, Dr. Pothmann plays a key role in ensuring that patients at the Westphalian Joint and Endoprosthetics Center can rely on the highest standards of medical care.
The editorial team of the Leading Medicine Guide spoke with Dr. Pothmann about the use of robotic assistance in joint replacement surgery, particularly the MAKO robotic system, which is primarily used in knee operations. Photo Dr. Matthias Pothmann
Robotic-assisted joint replacement is revolutionizing the implantation of artificial joints through maximum precision and individualized customization. Modern robotic assistance systems support surgeons in planning and performing procedures, particularly in hip and knee arthroplasty. With the help of high-resolution imaging and computer-assisted navigation, implants can be optimally positioned, resulting in improved fit and longevity. This technology, combined with minimally invasive techniques that minimize tissue damage, leads to faster rehabilitation and better functional outcomes. In specialized clinics, robotic-assisted surgery is increasingly being established as a forward-looking standard of care.
“Before the operation, a detailed analysis is created. In addition to conventional procedures, a three-dimensional image of the knee joint is first taken using a CT scan. This data is then processed in a special MAKO computer program so that the prosthetic components can already be virtually fitted in three dimensions. This means the surgery can essentially be planned in advance, including the size and position of the implant to match the bone. This results in optimized material planning, ensuring that the appropriate implants are available in sufficient quantity, making the surgery safer and more efficient. During the operation, the actual situation is compared with the pre-calculated data. Typically, the conventional, if possible minimally invasive, approach is chosen. With the help of an infrared interface and special detectors, about 60 preconfigured points on the knee are measured. These data are transmitted in real time to the computer, which is overseen by specially trained MAKO product specialists. These experts, who have undergone extensive training provided by the manufacturer Stryker, set up the robot and ensure continuous interface connection to the computer. The surgeon records the points on the knee, which are then matched with the CT data, allowing the robot to know precisely where specific structures—such as the ideal leg axis or certain areas inside the knee—are positioned in the three-dimensional world within fractions of a millimeter. The result is ultra-precise planning, with deviations often under 0.1 millimeter”, explains Dr. Pothmann, going into even greater detail about the advantages of robotics:
“All imaging data can be collected before the surgery and merged in the computer. This allows the procedure to be simulated down to the pixel, and planning with the MAKO system is usually done in close coordination with the MAKO technician to ensure the best possible implementation. The result is a very high degree of certainty that the actual operation will follow the virtual plan exactly. This enables precise bone cuts that are optimally tailored to the individual joint, as well as better control of ligament tension throughout the entire range of motion—an innovation that was previously not possible in knee surgery. Since the ligaments stabilizing the knee vary individually, the system makes it possible to simulate ligament tension even before making the cut. The simulation is performed during surgery to ensure that the knee remains stable and does not give way after implantation. The most important advantage is that ligament tension remains optimal throughout knee movement, which is very difficult to achieve with traditional surgery. Until now, knee surgery has depended heavily on the surgeon’s experience, as stability control could only be ideally derived from expertise. With the MAKO system, the learning curve is much steeper, meaning that even less experienced surgeons can achieve good results if they use the system regularly. The combination of a highly experienced surgeon and the MAKO is currently the gold standard in knee replacement. The system provides extremely precise, stable, and individualized treatment—a true breakthrough in knee surgery”. 
Photo MAKO System – ©Stryker.
It is essential that surgical competence and expertise are present in order to ensure a high-quality outcome in knee implant procedures.
“The surgical approach, the operative technique, and much more are also part of it. Conversely, one can say that if every orthopedic clinic in Germany were equipped with a MAKO system, the average outcomes would be significantly better, and complication rates—such as malpositioning or instabilities—would decrease. Overall, patient outcomes would most likely be much better, and I am firmly convinced that this will happen in the future. Currently, however, due to the financial pressures in the German healthcare system, this is hardly feasible. A system like this costs around three-quarters of a million euros, plus annual maintenance costs of about €55,000 to €60,000 for the technician who is present daily in the OR. In addition, the disposable materials required for the procedure cost around €480 per surgery. All of this must be considered in the calculations, without the patient having to make any co-payment. I hope that this will remain possible for a long time. We have been using the system since 2022. After a one-year leasing test phase to assess its performance, we decided to purchase it. I previously trained at a clinic that operates with four of these systems—the largest number in Europe. I was able to participate in the surgeries and learn the technology. For the specialists who work with the system in our clinic, special certification and intensive training were required. They only operate after comprehensive training, which also includes working on cadaver bones and synthetic bones, to ensure they are fully familiar with the technology”, says Dr. Pothmann, adding:
“Since we introduced the system, demand for MAKO-assisted knee operations has increased significantly. For most clinics, the incentive to purchase the system is not only because it improves surgical quality but also because it attracts more patients—raising the overall number of surgeries. At our clinic, that was not the primary reason, since our schedules were already fully booked, but in the affiliated hospitals where we introduced the system, we observed a clear increase in surgical volume because global research data is credible and demonstrates the benefits. There had already been attempts with robotics and navigation in orthopedic surgery, but only with the MAKO system has it been considered a revolutionary leap in improving outcomes. Naturally, the technology is also used for PR purposes to attract more patients. At our hospital, OR capacity has long been limited due to enormous demand. The system is also a prestige instrument for the hospital, reflecting innovation and positioning the institution against other clinics in Germany. It shows that we are at the forefront of modern methods and also have a strong international reputation. I am firmly convinced that this development will become standard in the future, provided the economic framework allows it. At present, however, it is difficult to represent all the advantages economically, as investment and operating costs play a major role and hospitals are increasingly under pressure to use their resources efficiently”.
Robotic-assisted joint replacement offers significant benefits, particularly for patients who require highly precise and individually tailored implantation. People suffering from severe joint deformities or advanced osteoarthritis can especially benefit from the high accuracy of this technology.
In modern joint surgery, innovative assistance systems such as the MAKO system are increasingly being used to improve precision during operations. In revision surgeries, where metal components are already present in the joint, the MAKO system cannot yet be applied as effectively. This remains a challenge that is actively being worked on, with the goal of integrating the MAKO system into revision procedures as well. Until then, it is primarily used in primary, i.e., first-time surgeries.
Dr. Pothmann explains: “In principle, we can use the system with almost every patient. The procedure is such that, in addition to the standard surgery on the tibial and femoral parts of the knee joint, two small metal antennas—so-called threaded pins—are temporarily inserted. These connect to the infrared interfaces, which are positioned according to the antennas during surgery. The antennas are inserted through small incisions above and below the joint. This is what distinguishes the technology from a conventional procedure, as they serve exclusively for navigation. They ensure that the data can be transmitted with complete accuracy, which would not be possible without these interfaces. In some patients, almost no scar remains, since the antennas are only about as thick as half a ballpoint pen, leaving barely visible marks. In hip surgeries, however, it is somewhat more complex, as the iliac crest must be opened to create the fixation points for the antennas. This means a larger wound and also more pain for the patient at that site. The advantages of MAKO in hip surgery are generally less pronounced than in knee surgery, because there are no complex ligament structures like the knee ligaments to consider. The positioning of the prosthetic components also proceeds as planned, but the clear advantage that the system offers, for example with unicompartmental knee replacement, is less evident in hip surgery. The key benefits of MAKO are clearly in knee surgery, especially for less experienced surgeons, since the technology significantly reduces the error rate. At our clinic, however, we have specialized in large, complex hip operations for years, and the knowledge and experience here are very advanced. For us, the added value of MAKO in hip procedures is comparatively smaller. In addition, the operation takes longer because the additional incisions for the navigation antennas must be opened and closed again, and with a minimally invasive approach the application is less straightforward. Overall, for experienced surgeons, the advantages in hip surgery are rather limited compared to the knee”.
The question arises whether the increasing spread and use of the MAKO system will lead to the training of future surgeons being more and more focused on this technology, while traditional, purely manual surgical methods slowly fade into the background.
“From my perspective, it remains essential to master the traditional surgical approach. The robot only assists in checking and simulating ligament tension and guiding the precise cutting plane. The actual work, such as sawing the bone, is still performed by the surgeon as usual—he holds the saw, presses the button, and makes the cut himself. The robot simply controls the cutting plane, ensures optimal positioning of the saw system, and holds it in the ideal position. Until now, conventional templates have often been used for such procedures, which may be standardized or individually manufactured based on CT or MRI planning. These templates are created using 3D printing and provide more precise orientation for the cut. They are a simpler, more cost-effective alternative compared to using the robot, but they cannot simulate ligament tension as accurately as the MAKO system. Although the robot holds the saw in the precise plane, the control and pressure for sawing are still carried out by the surgeon. Another major advantage of the robot is that it automatically stops if the saw moves outside the defined cutting area. In other words, it shuts off when the saw approaches vessels or nerves. This automatic stop feature enhances safety, especially for less experienced surgeons, and ensures that there is no risk of cutting into critical structures within the defined zone. That makes the use of the robot highly attractive from a safety standpoint—it is a feature that significantly increases overall safety”, emphasizes Dr. Pothmann.
In modern orthopedics, robotic-assisted implantation is gaining increasing importance. The question remains whether this technology will also have long-term positive effects on the durability of prostheses.
“The accuracy of fit during surgery is improved by the use of the robot. For example, in the femur, where the prosthesis must be precisely adjusted to five cut surfaces, the robot ensures an extremely accurate alignment so that the five surfaces of the prosthesis match exactly with the corresponding cut surfaces on the bone. This is important because the more precisely the parts fit together, the better the prosthesis locks in, integrates when cementless implantation is used, and the longer its lifespan. However, the durability of a prosthesis depends not only on the quality of the cut but also on the condition of the bone—whether it is soft or hard, and whether there is sufficient bone stock available. Even more crucial, though, is what the patient does and how the prosthesis is loaded. Overloading, loosening, or instability that causes pain often results from inadequate ligament support. This is one of the most common reasons why a prosthesis needs to be revised. The technology, meaning the use of the robot, improves not only the fit but especially the control of ligament tension, which significantly increases patient satisfaction. Deviations are minimized, leading to a significantly lower complication rate due to knee instability, which in turn reduces the risk of revision surgeries. The more precise execution contributes to extending the stability and longevity of the prosthesis”, states Dr. Pothmann.
Robotic-assisted joint replacement is currently in a phase of intensive research and development, promising further progress. The current state of the art shows continuous improvement of technologies, enabling surgeons to perform even more precise and individualized implantation of knee and hip prostheses.
“The technology will certainly continue to advance, possibly integrating even more high-tech elements. Artificial intelligence is already part of the system. Developers are constantly working to improve the system. Small innovations are continuously added—for example, color-coded components on the OR computer screen to better identify where cuts have already been made, where material still needs to be removed, and to avoid cutting into areas that should remain untouched. Revision arthroplasty will eventually also be integrated. Progress involves both hardware—the further development of the robot—and, most importantly, software. One drawback, however, is that the system is not compatible with every prosthesis. You are essentially tied to a specific company. The system is used with a certain prosthesis, one we had already been using predominantly before the MAKO era—one of the most successful and widely implanted prostheses worldwide. Nevertheless, in some ways, you remain bound to a company if you want to continue using the MAKO system”, says Dr. Pothmann, adding:
“If, for example, autonomous driving technology were already safely on the market in Germany, manufacturers could develop a kind of monopoly. Once people are convinced, they increasingly want that system because it is the best. With any new technology, the pioneers are naturally the ones who dominate the market. They are usually five to six years ahead of competitors and keep advancing the technology. There are other navigation and robotic systems on the market, but none have so far been able to match MAKO in terms of sawing precision, ligament tension analysis, and data management, even though competitors often claim otherwise. At the moment, however, MAKO remains technologically leading, and it will likely stay that way for several years until another system can compete on the same level”, explains Dr. Pothmann.
Over the past 10 years, the MAKO system has developed enormously. Today, the robot is in use in more than 35 countries worldwide. In Germany, Dr. Pothmann estimates that about 30 systems are in operation. It is impressive that more than 1.5 million surgeries have already been successfully performed with MAKO. Research in this field is very advanced, with over 400 scientific publications and more than 1,500 patent applications integrated into the system.
“After using the MAKO for about a year and being convinced of its long-term benefits, we decided to purchase the system. It is especially important in partial prostheses, so-called unicompartmental prostheses. When the indication is appropriate, this type of prosthesis is considered one of the most successful because, by carefully and precisely removing only the damaged part of the joint, the healthy structures are optimally preserved and the prosthesis can be ideally fitted. In practice, this is the greatest advantage, as it makes partial prostheses much more successful. With the MAKO, the outcomes of unicompartmental knee replacements have significantly improved once again. In 2021, the German Endoprosthesis Register recognized us as the clinic with the lowest complication rate after partial knee replacements, even though our case numbers were significantly lower than they are today. Today, with the MAKO, we perform far more of these surgeries, and the enthusiasm for this method is enormous”, explains Dr. Pothmann.  Ruth Löffler, Katharina Komor, Ellen Kiebist und Nadine Komor..jpg "Dr. Pothmann and team")
©Katholischer Hospitalverbund Hellweg
“World Record” at the Westphalian Joint and Endoprosthetics Center, Klinikum Unna
“On September 25, 2023, we even set a “world record” by performing eleven prosthetic surgeries with one MAKO in a single day. This had never been done before. The high patient demand for MAKO-assisted surgeries meant that many patients were on the waiting list, suffering from severe pain. Therefore, we dedicated a special day to these procedures, during which we operated in two ORs with two teams, working in shifts while the MAKO system was moved between the two rooms. This was only possible because only the core part of the surgery is performed with the MAKO—the incision and wound closure are done without it. The average surgical time for a knee replacement with MAKO is about 75 minutes. This is slightly longer than a conventional surgery, since setup and precise preparation with MAKO require additional time. However, the difference is relatively small—around 15 minutes”, says Dr. Pothmann.
©Katholischer Hospitalverbund Hellweg
After the 4,000th knee replacement since the founding of the orthopedics department in Unna and after the 500th MAKO-assisted knee replacement.
Dr. Pothmann makes one thing clear: “It is important that, in the event the MAKO system should ever fail, surgeons are also proficient in conventional surgical techniques. At our clinic, the system has never failed, but theoretically, it is possible. Therefore, it is crucial that the surgeon is always able to perform the operation safely without the robot. We only operate on patients if we would also operate on our own family members under the same circumstances and if the indication for surgery is clearly established. Ultimately, even with a medically clear indication, the patient always decides whether they want the operation. In Germany, every patient can have a necessary surgery such as a knee replacement covered by their health insurance. Care is available nationwide almost everywhere in Germany, provided the indication is there, which is why so many prostheses are implanted. In the future, only high-volume clinics will continue to be authorized for joint replacement surgeries. Switzerland is similar, but otherwise, there is no other country in the world where the system works this way for the benefit of the patient, since in other countries such procedures are either not covered or only partially covered by public insurance. In England, for example, such surgeries are often not covered by the healthcare system, meaning that many people simply cannot afford them. In this regard, the German system is very well structured. Criticism may be valid here too, but compared to other countries, the complaints about the German healthcare system are not justified”.
Thank you very much, Dr. Pothmann, for this impressive insight into robotic-assisted joint replacement!
