At the renowned Orthopedic Center (OFZ) in Weilheim, Priv.-Doz. Dr. med. Johannes Plath is a leading expert in orthopedics and trauma surgery, particularly in the field of shoulder and elbow surgery. His broad knowledge and extensive expertise enable him to offer a diverse range of treatment methods, encompassing both innovative surgical procedures and proven conservative therapies. His focus lies on minimally invasive procedures, traumatology, and joint replacement in the shoulder and elbow joints. His primary goal is always to restore maximum functionality and pain-free mobility to his patients.
PD Dr. Plath’s professional career began at the Technical University of Munich in the renowned Department of Sports Orthopedics under the direction of Prof. Dr. Andreas Imhoff, a leading expert in the field of minimally invasive joint surgery in Germany. It was here that he laid the foundation for his professional expertise and has continuously advanced his medical career. As a senior physician at Augsburg University Hospital, he expanded his knowledge and practical skills and successfully treated a wide range of complex cases. Particularly influential for his professional development was his training period with Dr. Laurent Lafosse in Annecy, France, a globally recognized pioneer in the field of shoulder and elbow surgery. There, PD Dr. Plath learned innovative surgical techniques and successfully incorporated them into his clinical practice.
In addition to his work as a physician, PD Dr. Plath is also active as a researcher and educator. His habilitation at the Technical University of Munich on the topic of “shoulder instability” underscores his commitment to the advancement of his field. As a member of the “Shoulder Instability” Committee of the Society for Arthroscopy and Joint Surgery (AGA), he makes a significant contribution to research and development in this field. Dedicated to the training of future physicians, PD Dr. Plath contributes his extensive knowledge as an AGA instructor and private lecturer at the School of Medicine at the Technical University of Munich. His personal goal is to always ensure the best possible care for his patients through empathetic support and tailored treatment strategies. The editorial team at Leading Medicine spoke with Dr. Plath to learn more about the latest and most innovative osteoarthritis therapies.
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Osteoarthritis, also known as joint wear and tear, is a gradual process characterized by the breakdown of joint cartilage. Osteoarthritis in the shoulder and elbow can develop due to various factors. In the shoulder and elbow joints, bones, cartilage, ligaments, and muscles work together to enable smooth movement. A major cause of osteoarthritis in these joints can be chronic overuse, resulting from repetitive strain, injuries, or certain activities—such as sports—that place heavy stress on the joint. Injuries such as fractures, dislocations, or ligament instability can also contribute to the development of osteoarthritis. Such injuries can damage the cartilage or impair normal joint function, thereby increasing the risk of osteoarthritis. A genetic predisposition can also influence the quality of cartilage tissue and thus increase the risk of developing osteoarthritis. In addition, age-related changes in the joint can play a role. As we age, cartilage gradually loses its elasticity and strength, which can lead to an increased risk of osteoarthritis. Factors such as being overweight, an unhealthy diet, and certain conditions like rheumatoid arthritis or metabolic disorders also increase the risk of developing osteoarthritis in the shoulder and elbow.
“A basic distinction is made between primary osteoarthritis, in which the cause is not precisely known and is likely genetic, and secondary osteoarthritis, which develops, for example, as a result of rheumatic diseases or tendon disorders. What we also see very often here is post-traumatic osteoarthritis, such as after accidents involving bone fractures or tendon injuries. Joint or cartilage injuries also lead to increased wear and tear. For example, if someone frequently dislocated their shoulder during their youth, this can manifest later in life as premature joint wear,” explains Dr. Plath at the beginning of our conversation.
Early Symptoms
The first signs of osteoarthritis often manifest as joint pain, particularly when moving the affected joint or after prolonged exertion. This pain may be accompanied by stiffness, especially after periods of rest or prolonged inactivity. The joint may become inflamed and swollen, which can lead to limited mobility and a crunching sound. These symptoms are sometimes misinterpreted as normal signs of aging, which can delay early diagnosis and treatment. If joint discomfort persists or osteoarthritis is suspected, it is therefore important to see a doctor to receive a thorough examination and appropriate treatment. “Many patients have usually been experiencing pain for quite some time before they finally sit down with me. They may have previously seen their primary care physician due to limited mobility, who might have simply recommended reducing physical strain for relief. But only early intervention can slow the progression of osteoarthritis and improve the quality of life for those affected through non-surgical measures,” says Dr. Plath, who then goes on to discuss the diagnostic process: “When the patient comes to see me, I first conduct a detailed interview with them to take their medical history. This is where I gather the most information during my shoulder/elbow clinic, and I often already have a good idea of the likely diagnosis. Following a physical examination, the preliminary diagnosis is then confirmed using imaging techniques such as X-rays, ultrasound, or MRI—which provides particularly clear visualization of the tendons. This completes the majority of the diagnostic process, and I can then classify the osteoarthritis.”
Innovative osteoarthritis therapies, supported by advanced technologies such as modular prostheses, 3D planning, and navigation using augmented reality, have marked a groundbreaking development in the treatment of osteoarthritis.
These advanced approaches open up new dimensions in personalized medical care, particularly in cases of severe deformities. “In advanced cases, when joint replacement is the only remaining option, a special CT scan is always performed, which provides me with an exceptionally precise view of the bone structure. Modular prostheses offer a flexible structure consisting of several interchangeable components that can be individually adjusted during surgery, and are generally standard practice in Germany. They follow a modular design principle. You can compare this to visiting a clothing store. There are winter jackets and tops in various sizes and colors. The patient’s needs must be taken into account. Does he still want to play sports? Does he use a walker for mobility? What is the reason for his prosthesis? The indication is important because the prosthesis can then be tailored precisely to him,” explains Dr. Plath, outlining the next steps.
During the procedure, the surgeon can combine and adjust various components to achieve an optimal fit and alignment. This improves the joint’s long-term functionality. Another advantage is the minimally invasive nature of the surgery. Smaller incisions and more precise adjustments can speed up recovery and reduce the risk of complications or tissue trauma. In addition, modular prostheses offer the option of replacing or modifying only specific parts as needed, without having to remove the entire prosthesis. This reduces the burden on the patient in the event of any revision surgeries or adjustments. Their flexibility and adaptability make modular prostheses a promising option, especially in complex cases of osteoarthritis.
“The procedure to implant a prosthesis usually takes about an hour. The inverse prosthesis, which is the most commonly used type, is a very robust implant that can be used even in cases of larger bone or tendon defects or osteoarthritis, unlike the anatomical prosthesis, which anatomically replicates the joint 100%. Typically, my patients stay in the hospital for about a week and then go directly to rehabilitation afterward. They are allowed—and in fact encouraged—to move around again immediately after surgery. “We use what’s known as a ‘fast-track approach’ in rehabilitation so that patients can quickly resume physical activity, build muscle, and regain mobility,” explains Dr. Plath.
The inverse prosthesis is a special type of shoulder prosthesis used when conventional shoulder prostheses are not suitable due to a torn rotator cuff or other factors such as severe bone damage. Unlike a conventional shoulder prosthesis, the inverse prosthesis has the components arranged in reverse: the spherical part of the prosthesis is attached to the shoulder blade, and the cup-shaped part is attached to the head of the humerus. This reversal of positions restores a stable center of rotation to the shoulder and improves the leverage of the shoulder muscles, particularly the deltoid muscle. People with severe osteoarthritis, rotator cuff tears, or other complex shoulder problems can benefit from this type of prosthesis. The inverse prosthesis can relieve pain and restore shoulder joint function by realigning the joint and improving mobility.
The introduction of 3D prosthesis planning has marked a significant advance in the customization of joint prostheses. By utilizing state-of-the-art imaging techniques such as CT or MRI scans, precise, customized planning for implantation can be achieved.
This technology enables surgeons to create an accurate three-dimensional model of the affected joint. Using these models, they can then plan the optimal positioning and alignment of the prosthesis in advance. This includes not only selecting the correct prosthesis size but also its precise placement in relation to the surrounding anatomical structures.
“CT-based 3D prosthesis planning offers surgeons a more comprehensive view of the patient’s individual joint, leading to more precise planning and an improved fit of the prosthesis—this should be standard practice today. Relying solely on X-rays for planning is a bit outdated. With CT-based 3D imaging, the accuracy of implant placement is significantly better. You can view the scapula in three dimensions and identify areas where the bone is strong or weak. This is important because the prosthesis is anchored in the bone of the scapula. During surgery, we can only see the surface of the socket, not the scapula, which lies behind it. Thanks to 3D planning, not only can the optimal size be calculated, but precise alignment and placement of the prosthesis are also possible—which is ultimately crucial for the long-term success of the implant. Some software systems also allow for planning of the humeral head, which has the advantage of enabling us to simulate how the shoulder will move in the future. This means the entire procedure can be simulated before surgery. We’re talking about a (virtual) surgery before the actual surgery. This can significantly minimize the likelihood of misalignment or inaccurate placement, which is crucial for extending the prosthesis’s lifespan and reducing potential complications. “The overall effort involved is not great, but it achieves the best possible outcome for the patient,” says Dr. Plath, describing the advantages of CT-based 3D prosthesis planning.
Augmented Reality (AR) navigation plays a crucial role in cases of severe deformities associated with osteoarthritis, particularly in the precise placement of joint prostheses. In cases of severe deformities, traditional surgical procedures can be challenging because they require precise orientation within anatomically altered tissue.
AR navigation provides the surgeon with an enhanced view of the surgical field during the procedure. This technology combines real-time surgical images with virtual information overlaid in real time. Using special glasses or screens, the surgeon can view the actual surgical field during the procedure while simultaneously seeing additional helpful information, such as anatomical structures, precise implant positions, or navigation cues.
“For the surgeon, 3D planning establishes the plan, but the challenge then lies in being able to translate that plan to the patient. This means considering which tools can be used to successfully implement everything and increase the precision of the implantation. For a very long time, patient-specific instruments were used, which were designed by the respective instrument manufacturer as drilling templates, produced by a 3D printer, and shipped to the surgeon. In cases of severe deformities, which often involve altered anatomy, AR navigation enables the surgeon to plan and align the prosthesis with even greater precision, even in complex situations. This is achieved by importing the previously completed 3D planning into navigation software. At the start of the surgery, the navigation system—which consists of two camera systems, one mounted on the patient and one on the surgeon’s instruments—must first be set up and then calibrated using a process known as surface matching. Afterward, the steps of the prosthesis implantation can be reproduced exactly as they were previously planned in the software. Throughout the entire operation, the surgeon views the surgical field through special AR glasses and is additionally supported by supplementary information projected into their field of view via the glasses—including the precise planning data—thus creating an augmented reality. “I myself use both the glasses and an additional monitor,” says Dr. Plath, explaining this innovative navigation system, and adds: “For cost reasons, navigation is not used for every patient, but only for those cases where it is very difficult to implement the planned procedure—specifically when anchoring must be precise to the millimeter and screw placement is more challenging.” Thanks to real-time visualization during the procedure, the surgeon can continuously monitor the placement and alignment of the implant and adjust it according to the prior 3D plans.
The long-term durability and functionality of the joint replacement prosthesis are positively influenced by the customization and better fit offered by modular prostheses.
A more precise adaptation to the patient’s individual anatomy can lead to reduced wear and tear and overall better function of the prosthesis over a longer period of time. This could result in a longer prosthesis lifespan and improved functionality compared to standardized prostheses.
“The crux of the matter is that you can never evaluate an innovation until much later, because the data we have today on long-term prosthesis longevity pertains to prostheses that were implanted 10–20 years ago. So we can’t say exactly how long something will last that we implant today using our modern techniques and implants. But there’s hardly any area of orthopedic joint replacement where as much has changed as in shoulder surgery,” notes Dr. Plath.
Rejection of a shoulder prosthesis is rare, but it can be caused by various factors.
“There is the issue of implant allergies, which is still the subject of critical scientific debate. Most commonly, patients report nickel allergies, such as from wearing costume jewelry or from contact irritation caused by metal pants buttons, for example. This is generally not a problem, as many manufacturers can already supply nickel-free implants, such as those made of titanium. A titanium allergy, on the other hand, is extremely rare. Unfortunately, in my opinion, there are still no solutions for shoulder arthroplasty in this regard. In cases of doubt, I advise against joint replacement and recommend non-surgical measures such as physical therapy or hyaluronic acid injections. Ultimately, the patient’s well-being is always the top priority. The patient must also always recognize and understand that the proposed and tailored treatment plan is indeed the best option for them. It’s a shame that shoulder replacement still has a reputation for not working. Yet so much has changed in this field over the past 20 years, especially when it comes to reverse prostheses,” explains Dr. Plath.
Visions for the Future
“I suspect that the technology will undergo another significant and extremely positive transformation through the use of AI (artificial intelligence) in augmented reality. It’s important never to forget that navigation, much like driving a car, is merely an assistance system. The surgeon must, of course, be able to perform the surgery even without navigation. Unfortunately, the healthcare system does not reimburse for navigation. Perhaps there will be an innovation surcharge someday,” Dr. Plath concludes our conversation on a positive note.
Thank you very much, Dr. Plath, for this detailed information on shoulder arthroplasty!
