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AAOS Now

Published 1/1/2016
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Terry Stanton

Evidence Bolsters Recommendations in New CPG

Surgical management of knee OA has 14 "strong" guidelines
A new Clinical Practice Guideline (CPG), available on the OrthoGuidelines.org website, provides a wealth of recommendations for Surgical Management of Osteoarthritis of the Knee (SMOAK).

Reflecting the improving quality of evidence to guide treatment decisions, the new CPG offers 14 recommendations based on "strong" evidence (Table 1) and 14 with "moderate" evidence. Ten others derive from "limited" evidence. Table 2 lists the complete summary of guidelines.

"Many of these guidelines carry strong recommendations because the literature and other evidence of good outcomes were very compelling," said David Jevsevar, MD, MBA, chair of the AAOS Committee on Evidence-Based Quality and Value.

"Earlier CPGs were challenging, because we didn't have the quality of evidence now available," said Kevin Shea, MD, Guidelines Section Leader. "Now the studies are better, leading to multiple recommendations based on strong and moderate evidence."

According to Brian McGrory, MD, chair of the guideline's Development Group, collaboration with specialty societies such as the American Association of Hip and Knee Surgeons (AAHKS) and The Knee Society, as well as other medical organizations, played a positive role in the creation of a robust product. "I am proud that these groups representing surgeons who specialize in knee arthroplasty contributed to this CPG through their participation," he said.

Risk factors covered
The SMOAK CPG covers a number of risk factors in TKA, including obesity, diabetes, chronic pain, depression/anxiety, and cirrhosis/hepatitis C. It finds strong evidence that obese patients have less improvement in outcomes. Moderate evidence points to a higher complication risk in patients with diabetes and to less improvement in outcomes in those with select chronic pain conditions. Factors such as depression/anxiety and cirrhosis/hepatitis C are supported by limited evidence.

When counseling patients about addressing risk factors, surgeons may rely on moderate evidence supporting the recommendation on delaying TKA. "Some healthcare systems have a wait list or the surgeon's schedule may be months out," Dr. Shea said. "Increasingly, population demographics are increasing demands on the time of joint surgeons. An 8-month delay does not appear to worsen outcomes according to this moderate recommendation.

"The flip side is what level of delay is associated with a worse outcome, and I don't know if we have the answer to that question. So I think surgeons can advise patients that a 6- to 8-month delay will not worsen outcomes."

Perioperative recommendations
Recommendations cover a range of topics, issues, and procedures. Two recommendations support specific modalities (periarticular local anesthetic infiltration and peripheral nerve blocks) to decrease postoperative pain and reduce opioid use following total knee arthroplasty (TKA).

A strong recommendation supports postoperative mobilization and rehabilitation started on the day of surgery as effective in reducing length of hospital stay. Several other strong recommendations oppose the use of certain techniques and treatment measures, including intraoperative navigation, patient-specific instrumentation, drains, and continuous passive motion (CPM).

"At one time, CPM was used routinely," said Dr. Shea. "Now many surgeons have stopped using it. The guideline shows clearly that we don't have to use CPM on a routine basis." Moderate evidence also indicates that use of cryotherapy devices after TKA does not improve outcomes.

The CPG cites strong evidence regarding use of either all-polyethylene or modular components and states that no difference in pain or function is seen with or without patellar resurfacing. However, a separate moderate recommendation supports the possibility that patellar resurfacing could decrease cumulative reoperations after 5 years.

Moderate evidence indicates that the use of tourniquets decreases intraoperative blood loss, and a strong recommendation states that their use increases short-term postoperative pain.

"I suspect that using a peripheral block would negate the increase in pain with tourniquet use," Dr. Shea said. "But if the choice is between postoperative pain and increased risk of blood transfusion, I personally would favor the pain, which is temporary, over the blood transfusion. This may be a personal patient decision."

The use of tranexamic acid to reduce postoperative blood loss is given a strong recommendation. "Postoperative transfusions are a real concern, with a lot of effort to reduce the rate of their use," Dr. Shea said. "I think tranexamic acid goes a long way in improving outcomes for patients."

Not without controversy
Drs. Shea and Jevsevar agree that certain recommendations may generate controversy or disagreement. One example in the SMOAK CPG may be the finding that limited evidence does not support the routine use of antibiotic bone cement in TKA.

"Surgeons may consider using antibiotic cement to lower the risk of infection, but the evidence may not actually support that," Dr. Shea said. "The other concern is antibiotic resistance, which encourages its use in a much more selective manner."

Other recommendations that might invite discussion include those on component fixation and the use of TKA for medial compartment arthritis to decrease the risk of revision for unicompartmental knee arthroplasty.

Three recommendations with limited evidence relate to therapy before and after surgery. They support preoperative physical therapy, a supervised exercise program in the first 2 months after TKA, and late-stage postoperative supervised exercise.

"This new guideline helps surgeons follow a patient through the pathway of their care and offers a lot of valuable information about how to make sure that pathway is optimally designed," said Dr. Shea.

Dr. Jevsevar emphasized that CPG recommendations are not meant to be prescriptive or edicts. "The guidelines reflect the current evidence, as it exists. Physicians should take that evidence, as well as their clinical experience, in assessing the patient's needs, and apply it appropriately. The AAOS wants surgeons to understand the evidence and make appropriate decisions for patients.

"Evidence for a limited recommendation may change over time," he continued. "With a strong recommendation, it is unlikely that that evidence is going to change. This CPG is a great compendium of the best evidence that physicians can use to guide their treatment for patients undergoing knee replacement. And overall, the evidence base for orthopaedics has continued to improve significantly."

The SMOAK CPG has been endorsed by the Arthroscopy Association of North America (AANA) and the Society of Military Orthopaedic Surgeons (SOMOS). Both AANA and SOMOS were represented on the guideline work group, as was the American Orthopaedic Society for Sports Medicine.

The complete guideline can be found at www.orthoguidelines.org

Terry Stanton is a senior science writer for AAOS Now. He can be reached at tstanton@aaos.org