Perhaps more than any other advance in orthopaedic surgery, total joint arthroplasty has improved the lives of millions of patients. Originally introduced in the form of hip replacement, nearly all of the major joints of the musculoskeletal system can now undergo arthroplasty, and total knee arthroplasty has established itself as one of the most successful interventions for reducing pain and improving function and quality of life. All total joint arthroplasties are associated with a risk of failure, and it is believed that, with the exception of the oldest patients, most individuals who undergo an arthroplasty will require a revision at some point during their lifetime. With total knee arthroplasty, advances in implant materials and design as well as operative technique have increased implant longevity and decreased the rate of revision to <5% within ten years.
As is typical of a successful intervention, surgeons who perform total knee arthroplasty recognize the need or opportunity to “push the envelope.” There is great demand for offering knee arthroplasty to younger, more active patients, and, in doing so, it is projected that the number of revision procedures will grow from the current annual incidence of 38,000 up to 270,000 by the year 2030. Thus, understanding the causes of failure will be essential for guiding future strategies.
In this month’s article by Bou Monsef et al., a systematic approach to identifying mechanisms of failure and appropriate treatment protocols for failed total knee arthroplasty are introduced. The authors make the important point that avoiding operative intervention before a diagnosis is made, even in cases of pain with no clear etiology, is essential. Individual discussions on the roles of infection, loosening and component failure, instability, stiffness, patellofemoral complications, and even neuromas are presented and placed in their proper perspective.
Indeed, one of the greatest frustrations in orthopaedic practice is the inability to identify the causative factors for a condition. The failure of a total knee arthroplasty may be associated with one or more contributing factors, including rare and unusual conditions such as the formation of heterotopic bone, the development of complex regional pain syndrome, the occurrence of hemarthrosis, and even hypersensitivity to certain metals. Interestingly, up to 17% of the general population expresses some sensitivity to the metals used in total knee implants such as nickel, chromium, and cobalt.
Failure of total knee arthroplasty can be devastating to the patient, but early diagnosis and careful systematic analysis of the potential etiologies can lead to a favorable outcome. This article provides a clear and concise approach to this problem and is a “must read” for surgeons who perform this operation now and the residents and fellows who will be caring for these patients in the decades to come.
Thomas A. Einhorn, MD, Editor
Thomas Thornhill, MD is the John B and Buckminster Brown Professor of Orthopaedic Surgery at Harvard Medical School and Chair of the Department of Orthopaedics at Brigham and Women’s Hospital in Boston. He recently was kind enough to answer a few questions for OrthoBuzz.
JBJS: What are some of the most significant changes in orthopaedics you have observed during your career?
Dr. Thornhill: The quality of applicants to orthopaedic residency programs seems to improve every year. I think anyone involved today in choosing new residents feels that he or she would never have been chosen by contemporary standards. Moreover, our profession has become more diverse, which is a good thing. Our residency/fellowship program has a significant number of women and underserved minorities. The most impressive thing is that there is a single set of criteria for all applicants, giving us a uniformly outstanding resident pool.
Also, the emerging use of biologics has enhanced our ability to care for some common and uncommon musculoskeletal problems. For example, the use of disease-modifying anti-rheumatic drugs (DMARDs) has revolutionized the care of the rheumatoid patient. When I began practice, 80 percent of patients undergoing total joint arthroplasty had rheumatoid arthritis, and now it is only approximately 10 percent in a center well-known for treating the rheumatoid patient.
Third, I’ve seen significant changes in the globalization of orthopaedics. The internet and social media have improved global communication. Many of the meetings in arthroplasty are global in their scope, and we are learning a tremendous amount from our orthopaedic colleagues around the world.
JBJS: Brigham and Women’s Hospital is recognized as a leader in providing patient-centered, team-based care. Why is this approach so important to orthopaedic patients?
Dr. Thornhill: Brigham and Women’s Hospital does not exist in a vacuum, and the Boston area has many fine academic and community hospitals with strong orthopaedic programs. Each subscribes to the concept of providing the right care, at the right place, and at the right time. Moreover, the changes in healthcare systems in Massachusetts and throughout the United Sates require each of us to be innovative. In the past, clinical surpluses could be used for educational and research program funding, but with the shrinking healthcare economy, there are many essential, but non-remunerative programs that are in jeopardy. Efficient, team-based care is one way to ensure we have the resources to continue these important educational and research programs. Finally, the switch from fee-for-service to episode-of-care reimbursement and population health is going to require each of us to adjust to inevitable changes in healthcare. In this environment, patient-centered, team-based care makes the most sense to ensure optimal outcomes.
JBJS: Orthopaedists are increasingly focused by subspecialty. What do you see as the benefits and risks of increased subspecialization within orthopaedics?
Dr. Thornhill: We are indeed becoming more and more subspecialized. One benefit is that it will certainly improve expertise in these areas, where patient demand is growing in an exponential fashion. It will also allow specialists to remain current in their subspecialty and prompt innovation in these different fields of orthopaedic practice.
On the other hand, intensive subspecialization may prevent us from “thinking outside the box.” Communication and idea crossover are important, and while we know many of the leaders in our own subspecialty, we don’t know many in other areas. Most of the meetings now are subspecialty-driven and fail to benefit from sharing of ideas with other subspecialties. Our graduates now virtually all take a fellowship, and 15 percent of them take two fellowships. One could argue that a trauma surgeon or musculoskeletal oncologist should have arthroplasty experience because there is a good deal of overlap within these disciplines. We should also remember that lessons learned in one specialty may benefit another. For instance, hip surgeons have long considered neck shaft angle, offset, and even material properties that have now been incorporated into the design and implantation of shoulder prostheses.
JBJS: How do you think JBJS can best address the needs of the orthopaedic community in light of this increasing subspecialization?
Dr. Thornhill: JBJS needs to maintain its preeminence as the leading orthopaedic journal. To do so, it must remain relevant, explore other mechanisms in addition to a printed version to transmit information, and the articles must remain balanced throughout the various subspecialties. I think JBJS has done an outstanding job moving into electronic media. One concern is the economics of maintaining The Journal’s viability and the concerns of some young authors about the cost of submitting a manuscript.
JBJS: Looking ahead to the next 20 years or so, what three significant advances or changes in orthopaedics do you foresee?
Dr. Thornhill: To paraphrase the book Future Shock, “If you want to see what is in the future, look around because it is happening somewhere now.” I think there will be an increased use of biologics in applications such as induction of bone formation, cartilage repair, tissue engineering, and the use of stem cells for repairing and regenerating musculoskeletal structures.
Also, we will look back several years from now and laugh at the materials we currently use for total joint replacement. One important concern in my area of interest is that 15 to 20 percent of patients undergoing total knee replacement are not completely satisfied, while many people with total hips and total shoulders forget they had an implant. I think the cause is multifactorial, but I do think that we will develop or engineer materials with characteristics that will improve the kinematics of knee prostheses, and hopefully our patients will feel that their knee replacements are more normal.
Finally, there will be an increase in technology, manufacturing, and research and development on a global scale. Global cooperation and time zone differences can allow manufacturing, design, and outcome studies to occur 24-7 in a more cost-effective fashion. If we also foster the interactions between academia and industry in a controlled fashion, we will further appreciate the tremendous advances in our specialty due to these relationships.
JBJS: What is your favorite thing about your profession?
Dr. Thornhill: The hackneyed phrase is that we get instant gratification from pain relief and restoration of function in our patients. While this is true, when I trace my training from internal medicine to orthopaedics, I recall drawing a Venn diagram showing that the three things I liked the best were surgery, rheumatology, and neurology. The only true intersection among those is orthopaedics. I would say that other than my family, I appreciate my interactions with students, residents, fellows, and colleagues, and I thoroughly enjoy treating my patients as people. Finally, I like the operating room and the technical aspects of orthopaedics.
JBJS: Thank you, Dr. Thornhill, for your time.