Consensus panel: TKR safe, cost-effective for alleviating pain

Volume affects outcome; no consensus on best way to minimize infection, thromboembolic disease.

Issue: January 2004

Total knee replacement is safe and cost-effective for alleviating pain and restoring physical function in patients who have not responded to nonsurgical therapies, according to the consensus statement of an independent panel convened by the National Institutes of Health.

“TKR is not for everyone — it’s a major elective surgery that carries a variety of important risks, but it offers dramatic relief after other therapies fail,” said E. Anthony Rankin, MD, the panel chair, in a news release.

The panel concluded that 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% of patients, and 85% of patients are satisfied with the results of surgery,” the panel concluded.

Joshua Jacobs, MD, said the message about the safety and efficacy of TKR “came through loud and clear” during the three days of the conference, held in December in Bethesda, Md. Jacobs, on the research committee of the U.S. Bone and Joint Decade and section editor of Orthopedics Today’s Basic Science section, said that the consensus statement “helps establish TKR as effective and makes clear that it should be done on more patients” who currently may lack access to the procedure or who have been offered the procedure but have not followed through due to as yet unidentified psychosocial factors.

The consensus statement also identified several areas in which research is needed, Jacobs said. “The quality of literature on patient outcomes can be improved, with higher levels of evidence to support what we do. The consensus should also provide an impetus for research in basic science in several areas.” This emphasis on further research into a major musculoskeletal health problem with a high burden of disease is quite timely given the presidential proclamation of 2002 to 2011 as the National Bone and Joint Decade.

Procedure volume an issue

One of the clearest associations with better outcomes in TKR appears to be the procedure volume of the individual surgeon and the hospital, according to the consensus statement.

The highest complication rates have been observed in surgeons who perform 12 or fewer TKR procedures per year and in hospitals where fewer than 25 procedures are performed each year. “Basically, the more they do, the better they do it,” said Rankin, an orthopedic surgeon at Providence Hospital in Washington, D.C.

Douglas W. Jackson, MD, said this issue has been discussed repeatedly. “Twelve has been a frequent minimum other groups in the past have concluded. That averages out to one TKR per month.

“This consensus conclusion will generate significant discussion in the orthopedic community and has wide-ranging implications on some orthopedic surgeons, residency and fellowship training and will — and is — being extrapolated to other procedures,” said Jackson, chief medical editor of ORTHOPEDICS TODAY.

The panel agreed that candidates for elective TKR should have radiographic evidence of joint damage, moderate to severe persistent pain that is not adequately relieved by an extended course of nonsurgical management, and clinically significant functional limitation.

Patients should be informed about the likely consequences of the surgery that are specific to their situation. “Any discrepancies between the patient’s expectations and the likely surgical outcome should be discussed in detail before surgery,” the panel said.

Complications can include wound-healing problems, wound and deep-tissue infection; deep-vein thrombosis and pulmonary embolism; pneumonia; myocardial infarction; patellar fracture; joint instability or malalignment; and nerve and vascular injuries.

Short- and long-term outcomes

In addition to procedure volume, other factors influence both short- and long-term outcomes, according to the consensus statement. One critical factor is proper alignment of the prosthesis. Computer navigation may eventually reduce the risk of malalignment but the benefit of such expensive technology remains unclear, the panel said.

Even though there are many prosthesis designs on the market, their “relative merits are generally unclear. Many design features, such as use of mobile bearings or designs that spare cruciate ligaments, have theoretical advantages, but durability and success rates appear roughly similar with most commonly used designs,” the statement said.

Jacobs, who was a presenter at the conference, said the consensus should spur research about why some devices fail.

The panel recommended that patients be provided with an information card about prosthesis design and date of manufacture.

The panel noted a lack of consensus about which medical and rehabilitative perioperative practices best minimize infections, thromboembolic disease, postop anemia and pulmonary infections.

This lack of consensus is due, the statement said, to a lack of well-designed studies testing the efficacy of such practices, including methods to reduce the incidence of deep venous thrombosis following TKR.

According to Jackson, orthopedic surgeons would like to see consensus opinions related to preventing thromboembolic disease and managing preop blood preparation, including anemia, as well as postop blood loss.

“Even within some institutions, the approach to these areas of management of the TKR patient vary significantly,” Jackson said. “Over the years, strong advocates for a given approach have presented studies that are not conclusive and often lack sufficient numbers, adequate controls and comparison. Preventing thromboembolic disease and infections is something every surgeon who is doing TKR, regardless of the number, would like to have better data to base their treatments on.”

No evidence-based guidelines exist for promoting or limiting post-TKR physical activity, according to the consensus statement. Also there is no consensus about how to prevent or treat postop anemia, or whether epidural analgesia or intravenous narcotics is the better method. “However, there is consensus that pain should be managed aggressively,” the panel said.

A consensus was identified regarding preoperative cardiac risk assessment, which should be performed prior to TKR. Smoking cessation should be recommended for all smokers preoperatively, with cessation initiated at least two months prior to surgery if possible.

“The impact of smoking on the biology of healing and resistance to infection is an area that has been documented in different areas and diseases,” Jackson said. “It is of particular interest to me that the consensus panel made a suggested cessation of smoking for at least two months before TKR.

“I will read the supporting literature for this specific recommendation more carefully and spend more time documenting the smoking patterns in my patients,” he said.

A decision to revise should consider several factors: presence of disabling pain, stiffness, functional impairment unrelieved by appropriate nonsurgical management and lifestyle changes. Additionally, evidence of progressive and significant bone loss, fracture or dislocation of the patella, instability of the components or aseptic loosening, and infection are also sufficient reasons to consider revision, according to the consensus statement.

Contraindications include persistent infection, poor bone quality, highly limited quadriceps or extensor function, poor skin coverage and poor vascular status.

The panel said, “It is critical to identify the cause for failure,” because early loosening can result from poor surgical technique, infection, mechanical overload or osteolysis. “Osteolysis appears to result from an inflammatory reaction to particulate debris generated from the prosthesis,” the panel said.

Even though a greater percentage of women have arthritis, they are less likely to have TKR. Racial disparities have also been identified.

The panel noted that these disparities are not different from disparities in a number of other procedures and could be due to some groups of patients’ limited familiarity with the procedures as well as mistrust of the health care system.

Jacobs said the consensus should open up research opportunities to understand why the procedure is “significantly underutilized. There seems to be unnecessary disability for certain segments of the population” who currently do not undergo the procedure despite the fact that they may be excellent candidates.”

Future research needed

The panel proposed a research agenda, including gathering data on the societal burden of knee disability and treatment costs. The panel proposed a prospective, longitudinal, population-based cohort to determine how knee disability develops and how people do or do not access effective treatment, including TKR surgery.

For a broader assessment of the health care system, the panel suggested that a national, multicenter registry be established to gather data about the short- and long-term outcomes related to TKR. The panel also recommended randomized, controlled trials to evaluate select aspects of TKR, including one related to prophylactic anticoagulation.

More research is needed from a patient’s perspective, the panel said. Currently, “we know little about the patient-level factors affecting outcomes, including medical and sociodemographic characteristics, participation in rehabilitation services, the extent of social support, and the level of patients’ physical activity.”

The text of the consensus statement can be found at http://consensus.nih.gov.