NIH Consensus Panel confirms TKR effectiveness
Calls for more research into racial, ethnic and gender disparities
By E. Anthony Rankin, MD and Sandra Lee Berner
To explore and assess the current scientific knowledge regarding total knee replacement (TKR), the National Institutes of Health Office of Medical Applications of Research and the National Institute of Arthritis and Musculoskeletal and Skin Diseases, components of the U.S. Department of Health and Human Services, sponsored the first-ever Consensus Development Conference on TKR, December 8-10, 2003. Consensus panel chair, E. Anthony Rankin, MD, Chief, Orthopaedic Surgery, Providence Hospital, Washington, D.C., and Secretary of the AAOS Board of Directors, said, “The conference’s purpose was to evaluate available scientific information on biomedical technology and develop a consensus statement that advances understanding of the technology or any issue in question that will be useful to health professionals and the public.”
An 11-member panel was charged with reviewing all available evidence on TKR. It included practitioners and researchers in orthopaedics, rheumatology, internal medicine, nursing, physical therapy, rehabilitation, biostatistics, epidemiology and health services research, as well as a TKR patient.
AAOS members who presented to the panel included Thomas S. Thornhill, MD; Peter F. Sharkey, MD, MS; Joshua J. Jacobs, MD; Robert B. Bourne, MD, FRCSC; Richard D. Scott, MD; Gerard A. Engh, MD; E. Michael Keating, MD; Chitranjan S. Ranawat, MD; Aaron G. Rosenberg, MD; Nizar N. Mahomed, MD, ScD; and Khaled J. Saleh, MD.
“In this coalition approach, we had an opportunity to meet with experts in a range of relevant disciplines. They presented the latest research in current TKR practice and outcomes to the consensus panel,” said Dr. Rankin.
The panel’s discussion included current indications and outcomes for primary TKR; variables that affect short and long-term outcomes; medical interventions that influence outcomes; indications, approaches and outcomes for revision TKR and salvage procedures, and disparities in the utilization of TKR.
According to Dr. Rankin, the panel reviewed “an extensive collection” of medical literature related to TKR, including a systematic literature review prepared by the Minnesota Evidence-Based Practice Center, under contract with the Agency for Healthcare Research and Quality.
“The panel concluded that 20 years of follow-up data indicate that the procedure is successful in the vast majority of patients,” said Dr. Rankin. “For persons suffering from intractable and persistent knee pain and disability, TKR surgery is safe and cost-effective therapy that restores mobility and alleviates discomfort.”
According to research, TKR has shown increasing success in relieving knee pain and improving joint function for patients suffering from knee problems due to injury, degenerative disease and inflammation. Each year, approximately 300,000 TKR surgeries are performed in the United States for end-stage arthritis of the knee joint. As the number of TKR surgeries performed each year increases and the indications for TKR extend to younger patients, a review of available scientific information is necessary to enhance clinical decision-making and stimulate further research.
“Advances in TKR technology within the past 10 years have enhanced the design and fit of knee implants, resulting in improved short-term and long-term outcomes,” said Dr. Rankin. “However, despite the increased success of TKR, questions remain concerning which materials and implant designs are most effective for specific patient populations and which surgical approach is optimal for a successful outcome.”
Research shows that physical, social and psychological issues may influence the success of TKR and that understanding patient differences could facilitate the decision-making process before, during and after surgery, thereby achieving the greatest benefit from TKR. Particular attention also must be given to the treatment and timing options related to the revision of failed TKR surgery.
The panel also reported that there is clear evidence of racial, ethnic and gender disparities in the provision of total knee replacements, as there are for many other health care interventions, but the reasons for this are unclear. Physicians’ beliefs about their patients, limited familiarity with these procedures in minority communities and patient mistrust of the health care system may all have a role. The consensus panel called for more research to determine the causes of these disparities.
“TKR is not for everyone — it is major elective surgery that carries a variety of important risks, but it often offers dramatic relief after other therapies fail,” said Dr. Rankin. “The panel emphasized that for patients considering TKR, important factors to consider include surgeon and hospital volume of TKRs performed, as these are associated with lower complication rates. Basically, the more they do, the better they do it.”
These findings were part of the panel’s consensus statement presented at the close of the three-day conference. The panel’s statement is an independent report and is not a policy statement of the NIH or the Federal Government.
A summary of the Evidence Report on Total Knee Replacement is available at http://www.ahrq.gov/clinic/epcsums/kneesum.htm.
A draft statement of the Consensus Conference conclusions is posted on Web site: http://consensus.nih.gov/ cons/117/117cdc_statement2.htm. The archived videocast of the conference sessions is available at http://videocast. nih.gov/PastEvents.asp?c=1.
Cosponsors included the National Institute of Child Health and Human Development, the U.S. Food and Drug Administration , the National Institute of Standards and Technology and the NIH Office of Research on Women’s Health.”
Primary TKR is most commonly performed for knee joint failure caused by osteoarthritis (OA); other indications include rheumatoid arthritis (RA), juvenile RA, osteonecrosis and other types of inflammatory arthritis. The aims of TKR are relief of pain and improvement in function. Candidates for elective TKR should have radiographic evidence of joint damage, moderate-to-severe persistent pain not adequately relieved by an extended course of nonsurgical management and clinically significant functional limitation resulting in diminished quality of life.
The success of primary TKR in most patients is strongly supported by more than 20 years of follow-up data. There appears to be rapid and substantial improvement in the patient’s pain, functional status and overall health-related quality of life in about 90 percent of patients, and 85 percent of patients are satisfied with the results of surgery.
Short-term outcomes, as documented by functional outcome scales, are generally substantially improved after TKR. Functional outcome is improved after TKR for people across the spectrum of disability status. In general, prostheses are durable, but failure does occur.
Age younger than 55 at the time of TKR, male gender, diagnosis of OA, obesity and presence of comorbid conditions are risk factors for revision.
Factors related to a surgeon’s case volume, technique and choice of prosthesis may have important influences on surgical outcomes. One of the clearest associations with better outcomes appears to be the procedure volume of the individual surgeon and the hospital.
Technical factors in performing surgery may influence both the short- and long-term success rate. Proper alignment of the prosthesis appears to be critical. Many design features, such as use of mobile bearings or designs sparing cruciate ligaments, have theoretical advantages, but durability and success rates appear roughly similar with most commonly used designs.
There is consensus regarding the following perioperative interventions that improve TKR outcomes: systemic antibiotic prophylaxis, aggressive postoperative pain management, perioperative risk assessment and management of medical conditions and preoperative education.
The effectiveness of anticoagulation for the prevention of pulmonary emboli is unclear. There are insufficient data to support specific perioperative rehabilitation strategies, methods to reduce postoperative anemia, postoperative physical activity recommendations and the site of postacute care.
Revisions for TKR are done to alleviate pain and improve function. Fracture or dislocation of the patella, instability of the components or aseptic loosening, infection and periprosthetic fractures are common reasons for total knee revision.
A painful knee without an identifiable cause is a controversial indication. Contraindications for revision TKR include persistent infection, poor bone quality, highly limited quadriceps or extensor function, poor skin coverage, and poor vascular status. Results are not as good as with primary TKR; outcomes are better for aseptic loosening than for infections. When infection is involved, successful results occur with a two-stage revision. Failed revisions require a salvage procedure (resection of arthroplasty, arthrodesis or amputation), with inferior results compared with revision TKR.
There is clear evidence of racial/ethnic and gender disparities in the provision of TKR in the United States. Racial or ethnic differences in the provision of care are not limited to joint replacements. The limited role of economic and other access factors in these racial or ethnic disparities can be demonstrated by significant differences in the rate of procedures in the Veteran’s Administration system, where cost and access are assumed equivalent across race or ethnicity.
Patients’ acceptance of physician recommendations varies greatly. Among persons with a potential need for TKR, only 12.7 percent of women and 8.8 percent of men were “definitely willing” to have the procedure. The interaction between the patient and physician affects the final recommendations and the patient’s acceptance of those recommendations. Physicians’ beliefs about their patients, the limited familiarity with these procedures in minority communities, patients’ mistrust of the health care system and personal beliefs about the most effective treatment of joint problems may all have a role in these racial or ethnic disparities.
The goal of new population-based observational research is to discover the need for services among persons with knee disability and the extent to which this need is currently being met by resources available within the family and in the community at large (including the health care system).
Research into the impact of providers and the health care system should be broadened to include: all TKR variables related to the surgeon, such as training and experience; surgical technique, including type of prosthesis and implantation technique; selection and perioperative care of patients; quality and characteristics of the institution, such as infection control methods and surgical volume; preoperative and postoperative modalities, including rehabilitation therapy; and continuity of care, including the pre- and postoperative plan for longer term follow-up and physical activity. In addition to broadening the scope of variables studied, the outcomes assessment must include all persons who receive knee surgery, as opposed to a convenience sample of those who return to the surgeon, and the follow-up must be sufficiently long to encompass the expected life of the prostheses.
Research should identify the extent to which disparities in the use of TKR are the result of subjective differences across groups in perception of pain or disability and orientation to surgery (risk aversion or cultural affinity with the health care providers who might refer to surgery, or both); objective differences in access to care as a result of the potential financial burden and extent and kind of health insurance; or discrimination on the part of health care providers.
Research also should identify the patient-level factors affecting outcomes after surgery, including medical and sociodemographic characteristics, participation in rehabilitation services, the extent of social support and the level of a patient’s physical activity after the surgery.