Overcoming the Persistent and Challenging Dilemma Between Stability and Flexibility and Unveiling a New Age for Chinese-made “Medial-Pivot Knee”
Shanghai, China - Suzhou MicroPort Joint MedTech Co., Ltd., which is a subsidiary of Shanghai MicroPort Medical (Group) Co., Ltd. (“MicroPort®”), obtained the registration certificates for the implants of Aspiration™ and SoSuperior™ Medial-Stabilized Total Knee Replacement Systems from National Medical Products Administration of China (NMPA) recently. These are the first Chinese-made Medial-Stabilized total knee replacement systems that have obtained such approvals with independent intellectual property. The products are set to bring a more comprehensive total knee replacement solution to the Chinese patients suffering from degenerative knee diseases, which will clear the persistent and challenging dilemma between stability and flexibility for knee arthroplasties and provide the surgeons with a wider range of product options.
Degenerative knee diseases, also known as knee osteoarthritis, are among the most common diseases with the highest disability rates for the elderly people. The incidence rate of the knee diseases increases significantly as the patients become older; Moreover, obesity and running too hard for too long accelerate the knee wears and cause knee diseases. In China, the incidence rates of the diseases are 10%-17%, 50% and even up to 70% in the age groups of 40-60 years old, over 60 years old and over 70 years old respectively. During the period from 1990 to 2010, the average rate in all age groups soared by 45% in China, with the disability rate being the world’s second highest at 21.3%. The Total Knee Arthroplasty (TKA) is a major solution for treatment of middle and advanced-stage degenerative knee diseases. Statistics show that the TKA cases will rise to 400,000 in China in 2020.
Artificial joint researchers are faced with a critical challenge to figure out how the patient satisfaction can be elevated and the post-operative recovery can be quickened to restore the normal lives of the patients. Global researchers have been constantly exploring the functional substitution of the anterior and posterior cruciate ligaments for decades. The cruciate ligaments, including anterior and posterior cruciate ligaments, are critical components in a knee. They play a major part to retain knee stability and mobility functions, so much so that sports news often reports that athletes, especially soccer players, have to undergo surgeries or interrupt their careers due to cruciate ligament injuries. The first generation of modern knee implants, the so-called hinged knee, requires the removal of both anterior and posterior cruciate ligaments. It provided the patients only with post-operative flexion-extension movement and mechanical stability but hardly restored natural rotational mobility. The posterior cruciate-retaining knee emphasized in its design rationale the retention of the posterior cruciate ligament. Whether it can be retained in clinical practice, however, is subject to the individual conditions of the patients, so that the operations become more challenging and longer. Eventually, Prof. Robert Bourne at University Hospital, London Health Sciences Centre, University of Western Ontario in Canada indicated that almost 20% of conventional TKA patients were not satisfied with the outcome - which was mainly caused by post-operative knee instability. The patients usually complained of anterior sliding and instability as well as anterior femoropatellar pain and abnormal joint noise in daily life, especially when they went down stairs. Another type of knee implants is posterior-stabilized knee. This design uses a post-cam mechanism to replace the function of posterior cruciate ligament after sacrificing both the anterior and posterior cruciate ligaments. But it requires more bone resection with a higher risk of implant wear, and leaves the problems of sliding, anterior knee pain and abnormal joint noise unsolved when patients went down stairs. Thus far, the latest Medial-Stabilized Knee is the total knee implant which is closest to human anatomy. After removal of anterior and posterior cruciate ligaments, it applies the special designed insert as a substitute for both the anterior and posterior cruciate ligaments at the same time, which not only simplifies the surgical procedure but also reconstructs the medial-stabilized kinematics of natural knees.
The Aspiration™ and SoSuperior™ Medial-Stabilized Total Knee Replacement Systems adopt the unique and innovative highly bionic medial stabilized ball-in-socket design of MicroPort® Orthopedics, with the implant’s metal parts (the distal femoral component and tibial base) using cobalt-chromium-molybdenum alloy and the highly-bionic inserts using ultra-high-molecular-weight polyethylene. The safety of the design has been proved after decades of clinical practice, as the raw materials have become mainstream in the knee implant market. The Medial-Stabilized Total Knee Replacement System not only provides a wider range of joint motion and more reliable wear resistance, but also restores the kinematics of normal knees and maintains their stability in motion, which makes the post-operative kinematic features and patients’ gaits more natural to achieve ‘forgotten knees’ and further elevate the patients’ satisfaction.
The design rationale behind the Medial-Stabilized Knee stems from the unique Medial-Pivot Knee design rationale of MicroPort® Orthopedics. With more than 20 years of successful clinical results and 17 years of clinical follow-up study data, this design rationale not only solves the issue of knee pain, but also significantly elevates the patients’ post-operative satisfaction, which meets the requirement specified in a central government guidance released on January 30, 2019. The document, titled Opinion Regarding the Enhancement of Performance Review of the Grade 3 Public Hospitals, stipulates that the evaluation on satisfaction is one of the four benchmarks included in the performance review system for the Grade 3 Public Hospitals.
Since 1998, the MicroPort® Medial-Pivot TKA system has been marketed in the United States and demonstrated excellent implant survivorship (98.8%) and patient satisfaction (95%) at 17 years. With its result having been published in the journal Knee, the clinical study was designed by Prof. George A. Macheras, who is head of Orthopedic Department of “KAT” General Hospital of Athens in Greece. Prof. Macheras is one of the first doctors to perform the Medial-Pivot TKA and one of the doctors who have performed the most Medial-Pivot TKA cases. He commented that the patients who had undergone the Medial-Pivot TKA could get back on their feet on the next day after the ‘Fast Track Surgery’ and be discharged from hospitals three to four days after the surgery; Furthermore, most of the patients could achieve the recovery of function for demanding activities, such as mountain climbing and heavy manual work; The follow-up study also covered obese patients weighing up to 100 kilograms; They were satisfied with the post-operative outcome, which is extraordinarily successful in TKA. Also, a paper published in The Journal of Arthroplasty pointed out that patients who underwent the Medial-Pivot TKA scored better on the Forgotten Joint Score than those who underwent the conventional posterior-stabilized TKA. The patients were more likely to “forget” that they had undergone TKA.
As one of the world famous knee implants, the Medial-Pivot Knee products of MicroPort® Orthopedics have achieved over 600,000 cases globally in the past 21 years and upend the conventional wisdom that you cannot undertake high-intensity exercises after knee arthroplasties. In 2016, four-time Super Bowl Champion and NFL Hall of Fame Quarterback Mr. Terry Bradshaw signed an agreement with MicroPort® Orthopedics to promote the Evolution® Medial-Pivot Knee and educate patients about knee replacement, only several months after receiving a Evolution® Medial-Pivot Knee replacement and citing the excellent stability and flexibility of the product. In 2018, Ms. Carrie Rand, who is in her 50s, and Mr. Larry Rand, 77, had successful Medial-Pivot Knee replacement surgeries at Houston Methodist Willowbrook Hospital. Both have been avid runners and can continue with the hobby after the surgeries. Ms. Carrie Rand have had her seventh 5K race since her knee replacement surgery. She has also run a 10K and a mini-triathlon. Mr. Larry Rand placed second in his age group at a 5K race just 13 months after surgery.
Dr. Steven Incavo at Weill Cornell Medical College in the US, who is also Professor of Clinical Orthopedic Surgery – Institute for Academic Medicine, commented on the design of Medial-Pivot Knee and the features of knee implants: “Studies demonstrate excellent clinical longevity of the Medial-Pivot design. This may be attributed to maintaining the proper amount of conformity to provide anterior-posterior stability on the medial side of the knee and enough laxity on the more mobile lateral side of the knee so that the knee doesn’t undergo excessive sliding motion or constraint. This implant also has an excellent surface for cementing. The surface roughness allows for good cement interdigitation, reducing the risk of cement-implant debonding and bone-cement loosening. Finally, the surgical technique is simple and allows for reproducibility.”
Prof. Tiebing Qu, who is a famous joint surgeon, director of Joint Disease Diagnosis and Treatment Center, China Rehabilitation Research Center & Beijing Bo’ai Hospital, a member of the Standing Committee of Chinese Orthopaedic Association, Deputy President of Knee Committee of Chinese Association of Orthopaedic Surgeons, Deputy Head of Joint Surgical Group of Chinese Orthopaedic Association, commented, “The Medial-Stabilized Knee implant integrates stability and flexibility to provide higher level of stability when better meet the needs of knee’s physiological activities. The stability and flexibility of implants have been at odds with each other from the beginning, as flexibility decreases with increases in stability and vice versa. The Medial-Stabilized Knee implants do very well to integrate the two features in such a perfect manner.”
Prof. Haishan Wu, who is also a famous joint surgeon, a director-level surgeon with Shanghai Changzheng Hospital, Shanghai Ninth People’s Hospital of Shanghai JiaoTong University School of Medicine, Group Leader of Chinese Knee Society, Asia Pacific Arthroplasty Society Annual Conference Chairman, and a member of the Standing Committee of the Chinese Association of Orthopaedic Surgeons, commented, “Compared with the conventional knee implants, the Medial-Stabilized Knee implants have the features of being more bionic and better following knee kinematics. During last year’s Chinese Orthopaedic Association Congress, the top foreign orthopedic producers have also introduced relevant products. However, the design of Medial-Pivot Knee originates in MicroPort® Orthopedics with more than 20 years of clinical application. I believe that the launch of the Chinese-made products of MicroPort® Orthopedics will bring about more benefits to the domestic patients.”
In order to accompany the approved Chinese-made Medial-Stabilized Total Knee Replacement system, the R&D team of the MicroPort® Orthopedics China has also designed a set of instrument with fully independent intellectual property. The instrument set has undergone technical innovation and design improvement in accordance with the clinical practice in China, so as to better suit the surgical custom of Chinese doctors, bring more convenience, and make the procedure smoother.
MicroPort® Orthopedics China President Mr. Robin Weng said, “The approvals of the first total knee replacement systems that are made in China mark an additional improvement in MicroPort® Orthopedics’ product portfolio of Chinese-made joint implants. We will always adhere to the MicroPort® mission of ‘Innovating relentlessly to commercialize the best yet affordable therapeutic solutions to save, reshape or improve the patients’ lives’, and commit to the R&D and promotion of new techniques, rationales and products in the field of orthopedics, so as to have more Chinese patients benefit from our best yet affordable therapeutic solutions.”
MicroPort® Chief Operation Officer Ms. Glendy Wang said, “The stability and flexibility constantly constitute a dilemma in the R&D of knee implants, which are also the objectives that the global artificial joint developers have been tirelessly pursuing for years. As far as MicroPort® Orthopedics is concerned, we are not complacent only about imitation of Western products. Furthermore, the word “Aspiration™”, which is used to name one of the Medial-Stabilized Knee products and also one of our company’s eight core values, carries the following message: we hope to strive for more custom-made and suitable therapeutic products and techniques for the oriental patients and doctors, and conduct the innovative orthopedic R&D activities with a basis in China where the Western medical rationale is a dominant force and with passion for self-improvement, knowledge-based progress, and courageous exploration. Following the approvals for Aspiration™ and SoSuperior™, MicroPort® Orthopedics will create more orthopedic products with home-grown innovation to benefit the Chinese patients.”
 Bourne RB et al. “Patients satisfaction after total knee arthroplasty: who is satisfied and who is not?” Clin Orthop Relat Res, 2010.