Rationale
The American Academy of Orthopaedic Surgeons (AAOS), with input from representatives from the American Association of Hip and Knee Surgeons, the Arthroscopy Association of North America, the American Orthopaedic Society for Sports Medicine, the Society of Military Orthopaedic Surgeons, the American Physical Therapy Association, the Society of Hospital Medicine, and the American Society of Anesthesiologists, recently published their clinical practice guideline (CPG), Surgical Management of Osteoarthritis of the Knee: Evidence-based Guideline.1 The guideline contains 38 recommendations for improving the surgical treatment of patients with osteoarthritis (OA) of the knee based on current best evidence. This CPG was approved by the AAOS Board of Directors in December 2015, and has been officially endorsed by the American Association of Hip and Knee Surgeons, The Knee Society, the Society of Military Orthopaedic Surgeons, the American College of Radiology, the American Geriatrics Society, and the Arthroscopy Association of North America.
The guideline uses the updated process and language changes to the AAOS CPG program approved by the AAOS Evidence-based Quality and Value Committee (EBQVC) in 2013.2 At the introductory meeting, the work group proposed population, intervention, control, and outcome (PICO) research questions for each area of interest. The work group used the expanded criteria for (1) research quality designations, (2) the concept of “best-available evidence synthesis,” and (3) updated evidence rating categories and language. In the current AAOS guideline process, a consensus recommendation may be formulated by the work group if there is no supporting evidence and when not establishing a recommendation could have catastrophic consequences, such as loss of life or limb. No unanswered PICO questions fell into this category for this guideline. For the PICO questions with insufficient evidence to reach a conclusion, each query was forwarded on to an appropriate specialty society to serve as a potential area of future research.
The burden of OA of the knee is attributable to the effects of pain, stiffness, and disability, as well as the expense of treatment. Because the increasing prevalence of OA of the knee is partly a function of the increase in the average age and the rate of obesity in the United States, OA is the most frequent cause of disability among adults in the United States.3,4 In persons older than age 55 years, 10% have painful, disabling OA of the knee; of this group, one quarter are severely disabled.5 In patients with arthritis, approximately 5% undergo surgery. Although these surgeries are costly, they are cost-effective in the long-term.6,7 Arthroplasty of the knee is the most common reason for inpatient hospitalization, and 3 million women and 1.7 million men currently have undergone knee arthroplasty in the United States.8
To help improve surgical treatment of patients with OA of the knee based on the current best evidence, the AAOS leadership allocated resources to formulate an evidence-based CPG. The entire process adhered to the strict evidence-based CPG methodology developed by the AAOS; a member of the AAOS Committee on Evidence-based Quality and Value provided guidance by serving as an oversight chair. The work group formulated PICO questions that were designed to examine important and actionable interventions to create a clinically relevant document that addresses the surgical management of OA of the knee across the full episode of care. An extensive literature search was done to investigate these preliminary topics based on strict inclusion criteria designed to identify the best available evidence. Studies published in or after 1966 were included to ensure that no landmark studies were missed; however, most of the included studies were from the year 2000 and later. Using this time period best reflects advances in orthopaedic science and ensures that relevant, contemporary implants and techniques are being evaluated. The work group required that all studies have a sample size of at least 10 participants to limit the “small study” effect of lower-powered clinical trials. In the included studies, a minimum of 90% of patients had to have been diagnosed with OA of the knee; this was a compromise to avoid exclusion of valuable studies, and at the same time to ensure that inflammatory arthritis of the knee was not a primary diagnosis. The follow-up required in each study varied by PICO question, and was predetermined by the work group.
During the evidence analysis phase, 13,000 abstracts and more than 1,200 full-text articles were reviewed. The citations were summarized, classified by patient outcomes, and graded by strength of methodology representing best available evidence to be used by the work group to formulate final evidence-based recommendations. A “best-available evidence synthesis” form of evidence analysis was employed, meaning that, although all studies that meet the inclusion criteria were examined, only the highest levels of available evidence were used. Retrospective series, small case series, and case reports were sometimes excluded because of the inherent risk of bias or because higher quality of evidence was available to address the same question. The use of this best evidence protocol reduces the adverse or favorable effect of poorly designed studies on the final recommendation.
The recommendations underwent a rigorous internal and external peer review process resulting in the final approved CPG. Seven peer reviewers, representing multiple specialty societies, submitted formal peer reviews. The work group carefully considered each reviewer’s comments, responses were formulated and published, and changes were made as needed to the final document.
One theme that reviewers commented on was the inability to include stand-alone registry data and secondary research (ie, systematic and narrative reviews) as acceptable evidence. Currently, the only registry data acceptable for consideration in the CPG process are those published in the peer-reviewed literature. Retrospective analysis of registry data can lead to some of the flaws noted in observational research, namely bias, patient selection, and consecutiveness of reporting. Registries that embed prospective cohort studies within them are of acceptable quality for evidence-based analysis. For secondary research, analysts search through the bibliographies for any primary citations that meet the inclusion criteria. When appropriate, de novo meta-analyses are performed.
In summary, the guideline for surgical management of OA of the knee involved reviewing >13,000 abstracts and >1,200 full-text articles to develop 38 recommendations supported by 224 research articles meeting stringent inclusion criteria. Each recommendation is based on a systematic review of the research literature related to its topic which resulted in 14 recommendations classified as Strong, 14 as Moderate, and 10 as Limited. Strength of recommendation is assigned based on the quality of the supporting evidence.
Overview
To best impact patient care, pertinent highlights and limitations of the guideline recommendations are described so that they may be used in the appropriate context of the supporting evidence. Collectively, several themes emerge from these recommendations. Preoperative preparation with risk mitigation and rehabilitation is important for the best surgical outcomes. In addition, modern anesthesia and blood management techniques are helpful. Pros and cons exist about the use of unicompartmental knee arthroplasty (UKA) versus total knee arthroplasty (TKA) for isolated medial arthritis, as well as tourniquet usage and patellar resurfacing for TKA. No one fixation option has a strong advantage over another or for a cruciate-substitution design. In addition, no demonstrable advantages were shown for patient-specific instrumentation (PSI) or surgical navigation for routine TKA. Current evidence does not support the use of antibiotic-loaded bone cement, surgical drains, and continuous passive motion (CPM) machines. Finally, early postoperative mobilization and postoperative physical therapy are helpful for achieving the best outcomes.
Preoperative preparation with risk mitigation is important and safe. Strong evidence supports the finding that obese patients have less improvement in outcomes with TKA. Moderate evidence supports the findings that patients with diabetes mellitus are at a higher risk for complications and that patients with select chronic pain conditions have less improvement in patient-reported outcomes (PROs). Limited evidence supports the findings that patients with depression and/or anxiety have less improvement in PROs, patients with cirrhosis and hepatitis C are at a higher risk of complications, and supervised exercise before TKA may improve pain and physical function after surgery. Moderate evidence supports that a delay of 8 months prior to TKA does not worsen outcomes. These findings, when considered together, support the practice of optimizing the patient preoperatively when appropriate. For example, it is considered reasonable to delay surgery for up to 8 months to allow a morbidly obese patient to lose weight.9 Conversely, the recommendation does not suggest that a delay in surgery, when a patient is otherwise ready, is necessary. As pointed out during peer review and commented on in the rationale for this recommendation, an unnecessary delay does not take into account the patient’s pain and suffering nor does it address economic factors, such as loss of work.
Contemporary anesthesia and blood management techniques are supported. Strong evidence supports that both periarticular local anesthetic infiltration and peripheral nerve blockade for TKA decrease postoperative pain and opioid requirements. Moderate evidence supports that neuraxial anesthesia improves select perioperative outcomes and complication rates compared with general anesthesia. Strong evidence supports that treatment with tranexamic acid decreases postoperative blood loss and reduces the necessity of postoperative transfusions following TKA in patients with no known contraindications.
There are advantages and disadvantages of UKA versus TKA for isolated medial arthritis, as well as tourniquet usage and patellar resurfacing for TKA. Although limited evidence supports that partial arthroplasty may be used to decrease the risk of deep vein thrombosis and manipulation under anesthesia, moderate evidence supports that TKA may be used to decrease the number of revision surgeries. Regarding tourniquet usage, moderate evidence supports that a tourniquet decreases intraoperative blood loss, strong evidence supports that its use increases short-term postoperative pain, and limited evidence supports that its use decreases short-term postoperative function. Although strong evidence shows no difference in pain or function with or without patellar resurfacing in TKA, moderate evidence supports that patellar resurfacing in TKA may decrease cumulative revision surgeries after 5 years. Although these paired recommendations seem to be contradictory, they demonstrate that best evidence supports different outcomes depending on the intervention. Surgeons should use their judgment and patient preferences and values in determining the most appropriate surgical management.
No findings show a strong advantage regarding cruciate-substitution design, style of tibial component, or type of fixation. Strong evidence supports no difference in outcomes or complications between posterior-stabilized and posterior cruciate-retaining arthroplasty designs. Strong evidence supports use of either all-polyethylene or modular tibial components in knee arthroplasty because of no difference in outcomes. Strong evidence supports either cemented or noncemented tibial component fixation in TKA because of similar functional outcomes and rates of complications and revision surgeries. Moderate evidence supports the use of either cemented femoral and tibial components or noncemented femoral and tibial components in knee arthroplasty because of similar rates of complications and revision surgeries. Moderate evidence supports the use of either cementing all components or the use of hybrid fixation (ie, noncemented femoral component) in TKA because of similar functional outcomes and rates of complications and revision surgeries. Limited evidence supports the use of either all noncemented components or hybrid fixation (ie, noncemented femoral component) in TKA because of similar rates of complications and revision surgeries.
The use of navigation or PSI for routine TKA shows no demonstrable advantage. Strong evidence supports not using intraoperative navigation or PSI in TKA because no differences in outcomes or complications have been shown compared with conventional instrumentation. Moderate evidence supports not using PSI compared with conventional instrumentation for TKA because there is no difference in the rate of transfusions or complications. This wording is different than that seen in previous AAOS CPGs and reflects the 2013 CPG process update. In cases where an intervention, such as surgical navigation, is an additive procedure or technology, the wording “…evidence supports not using…” is employed to convey that the additive procedure or technology adds no benefit and should be avoided.
Drains, CPM, cryotherapy devices, and antibiotic-loaded bone cement are not supported. Strong evidence supports not using a drain with TKA because there is no difference in the rate of complications or outcomes. Likewise, strong evidence supports that the use of CPM after knee arthroplasty does not improve outcomes. Moderate evidence supports that the use of cryotherapy devices after knee arthroplasty does not improve outcomes. Limited evidence does not support the routine use of antibiotic-loaded bone cement in primary TKA. Although there are times when these interventions are appropriate, this information will be discussed in the rationale section of each recommendation.
Early postoperative mobilization and preoperative and postoperative physical therapy are helpful to achieve the best outcomes. Strong evidence supports that rehabilitation started on the day of TKA reduces the length of stay in the hospital. Moderate evidence supports that rehabilitation started on the day of TKA, compared with rehabilitation started on postoperative day 1, reduces pain and improves function. Moderate evidence supports that initiation of a supervised exercise program during the first 2 months after TKA improves physical function. Limited evidence supports that a supervised exercise program initiated during the first 2 months after TKA decreases pain. Limited evidence supports that selected patients might be referred to an intensive supervised exercise program during the late stage (>2 months) after TKA to improve physical function.
In summary, this guideline is meant to elevate and standardize the current level of surgical care of patients with OA of the knee and stimulate additional research where there is currently a deficit or where experience and evidence are not in agreement. The CPG is a document that captures best surgical treatment evidence as of January 27, 2015. New data will undoubtedly emerge over time that clinicians will need to evaluate in order to adjust and optimize ongoing care for their patients.
The recommendations in this guideline are not intended to be a fixed protocol, and as with all evidence-based recommendations, practitioners must also rely on their clinical judgment and experience as well as their patients’ preferences and values when making treatment decisions.
Recommendations
This summary of recommendations of the AAOS Surgical Management of Osteoarthritis of the Knee: Evidence-based Guideline contains a list of the evidence-based treatment and postoperative rehabilitation recommendations. Discussion of how each recommendation was developed and the complete evidence report are contained in the full guideline at www.orthoguidelines.org. Readers are urged to consult the full guideline for the comprehensive evaluation of the available scientific studies. The recommendations were established using methods of evidence-based medicine that rigorously control for bias, enhance transparency, and promote reproducibility.
This summary of recommendations is not intended to stand alone. Medical care should be based on evidence, a physician’s expert judgment, and the patient’s circumstances, values, preferences, and rights. For treatment procedures to provide benefit, mutual collaboration with shared decision-making between the patient and physician/allied healthcare provider is essential.
A Strong recommendation means that the quality of the supporting evidence is high. A Moderate recommendation means that the benefits exceed the potential harm (or that the potential harm clearly exceeds the benefits in the case of a negative recommendation), but the quality/applicability of the supporting evidence is not as strong. A Limited recommendation means that there is a lack of compelling evidence that has resulted in an unclear balance between benefits and potential harm.
Body Mass Index as a Risk Factor
Strong evidence supports that obese patients have less improvement in outcomes with TKA.
Strength of recommendation: Strong.
Diabetes as a Risk Factor
Moderate evidence supports that patients with diabetes are at a higher risk for complications with TKA.
Strength of recommendation: Moderate.
Chronic Pain as a Risk Factor
Moderate evidence supports that patients with select chronic pain conditions have less improvement in PROs with TKA.
Strength of recommendation: Moderate.
Depression/Anxiety as a Risk Factor
Limited evidence supports that patients with depression and/or anxiety symptoms have less improvement in PROs with TKA.
Strength of recommendation: Limited.
Cirrhosis/Hepatitis C as a Risk Factor
Limited evidence supports that patients with cirrhosis or hepatitis C are at a higher risk for complications with TKA.
Strength of recommendation: Limited.
Preoperative Physical Therapy
Limited evidence supports that supervised exercise before TKA might improve pain and physical function after surgery.
Strength of recommendation: Limited.
Delay Total Knee Arthroplasty
Moderate evidence supports that a delay of 8 months prior to TKA does not worsen outcomes.
Strength of recommendation: Moderate.
Periarticular Local Anesthetic Infiltration
Strong evidence supports the use of periarticular local anesthetic infiltration compared with placebo in TKA to decrease pain and opioid use.
Strength of recommendation: Strong.
Peripheral Nerve Blockade
Strong evidence supports that peripheral nerve blockade for TKA decreases postoperative pain and opioid requirements.
Strength of recommendation: Strong.
Neuraxial Anesthesia
Moderate evidence supports that neuraxial anesthesia may be used in TKA to improve select perioperative outcomes and complication rates compared with general anesthesia.
Strength of recommendation: Moderate.
Tourniquet Use and Blood Loss Reduction
Moderate evidence supports that the use of a tourniquet in TKA decreases intraoperative blood loss.
Strength of recommendation: Moderate.
Tourniquet Use and Postoperative Pain Reduction
Strong evidence supports that the use of a tourniquet in TKA increases short-term postoperative pain.
Strength of recommendation: Strong.
Tourniquet Use and Postoperative Function
Limited evidence supports that the use of a tourniquet in TKA decreases short-term postoperative function.
Strength of recommendation: Limited.
Tranexamic Acid
Strong evidence supports that treatment with tranexamic acid decreases postoperative blood loss and reduces the necessity of postoperative transfusions following TKA in patients with no known contraindications.
Strength of recommendation: Strong.
Antibiotic Bone Cement
Limited evidence does not support the routine use of antibiotic bone cement for primary TKA.
Strength of recommendation: Limited.
Cruciate-retaining Arthroplasty
Strong evidence supports no difference in outcomes or complications between posterior-stabilized and posterior cruciate-retaining arthroplasty designs.
Strength of recommendation: Strong.
Polyethylene Tibial Component
Strong evidence supports use of either all-polyethylene or modular tibial components in knee arthroplasty because of no difference in outcomes.
Strength of recommendation: Strong.
Patellar Resurfacing: Pain and Function
Strong evidence supports no difference in pain or function with or without patellar resurfacing in TKA.
Strength of recommendation: Strong.
Patellar Resurfacing: Revision Surgery
Moderate evidence supports that patellar resurfacing in TKA may decrease cumulative revision surgeries after 5 years compared with no patellar resurfacing in TKA.
Strength of recommendation: Moderate.
Cemented Tibial Components Versus Noncemented Tibial Components
Strong evidence supports the use of cemented or noncemented tibial component fixation in TKA as a result of similar functional outcomes and rates of complications and revision surgeries.
Strength of recommendation: Strong.
Cemented Femoral and Tibial Components Versus Noncemented Femoral and Tibial Components
Moderate evidence supports the use of either cemented femoral and tibial components or noncemented femoral and tibial components in knee arthroplasty because of similar rates of complications and revision surgeries.
Strength of recommendation: Moderate.
All-cemented Components Versus Hybrid Fixation
Moderate evidence supports the use of either cementing all components or hybrid fixation (ie, noncemented femoral component) in TKA as a result of similar functional outcomes and rates of complications and revision surgeries.
Strength of recommendation: Moderate.
All Noncemented Components Versus Hybrid Fixation
Limited evidence supports the use of either all noncemented components or hybrid fixation (ie, noncemented femoral component) in TKA as a result of similar rates of complications and revision surgeries.
Strength of recommendation: Limited.
Bilateral Total Knee Arthroplasty
Limited evidence supports simultaneous bilateral TKA in patients aged ≤70 years or American Society of Anesthesiologists status 1-2, because there is no increased rate of complications.
Strength of recommendation: Limited.
Unicompartmental Knee Arthroplasty Revision Surgery
Moderate evidence supports that TKA could be used to decrease the risk of revision surgery compared with UKA for OA of the medial compartment.
Strength of recommendation: Moderate.
Unicompartmental Knee Arthroplasty: Deep Vein Thrombosis and Manipulation Under Anesthesia
Limited evidence supports that UKA might be used to decrease the risk of deep vein thrombosis and manipulation under anesthesia compared with TKA for OA of the medial compartment.
Strength of recommendation: Limited.
Unicompartmental Knee Arthroplasty Versus Osteotomy
Moderate evidence supports no difference between UKA or valgus-producing proximal tibial osteotomy in outcomes and complications in patients with OA of the medial compartment.
Strength of recommendation: Moderate.
Surgical Navigation
Strong evidence supports not using intraoperative navigation in TKA because there is no difference in outcomes or complications.
Strength of recommendation: Strong.
Patient-specific Instrumentation: Pain and Function
Strong evidence supports not using PSI compared with conventional instrumentation for TKA because there is no difference in pain or functional outcomes.
Strength of recommendation: Strong.
Patient-specific Instrumentation: Transfusions and Complications
Moderate evidence supports not using PSI compared with conventional instrumentation for TKA because there is no difference in transfusions or complications.
Strength of recommendation: Moderate.
Drains
Strong evidence supports not using a drain with TKA because there is no difference in complications or outcomes.
Strength of recommendation: Strong.
Cryotherapy Devices
Moderate evidence supports that the use of cryotherapy devices after knee arthroplasty do not improve outcomes.
Strength of recommendation: Moderate.
Continuous Passive Motion
Strong evidence supports that CPM after knee arthroplasty does not improve outcomes.
Strength of recommendation: Strong.
Postoperative Mobilization: Length of Stay
Strong evidence supports that rehabilitation started on the day of TKA reduces the length of hospital stay.
Strength of recommendation: Strong.
Postoperative Mobilization: Pain and Function
Moderate evidence supports that rehabilitation started on the day of TKA compared with rehabilitation started on postoperative day 1 reduces pain and improves function.
Strength of recommendation: Moderate.
Early-stage Supervised Exercise Program: Function
Moderate evidence supports that a supervised exercise program during the first 2 months after TKA improves physical function.
Strength of recommendation: Moderate.
Early-stage Supervised Exercise Program: Pain
Limited evidence supports that a supervised exercise program during the first 2 months after TKA decreases pain.
Strength of recommendation: Limited.
Late-stage Postoperative Supervised Exercise Program: Function
Limited evidence supports that selected patients might be referred to an intensive supervised exercise program during late-stage postoperative TKA to improve physical function.
Strength of Recommendation: Limited.
