aaos clinical practice guideline summary …prevention of symptomatic pulmonary embolism in patients...

Prevention of SymptomaticPulmonary Embolism in PatientsUndergoing Total Hip or KneeArthroplasty

Abstract

This clinical practice guideline is based on a systematic review ofpublished studies on the management of adult patients undergoingtotal hip replacement (THR) or total knee replacement (TKR) aimedspecifically at preventing symptomatic pulmonary embolism (PE).The guideline emphasizes the need to assess the patient’s riskfor both PE and postoperative bleeding. Mechanical prophylaxisand early mobilization are recommended for all patients.Chemoprophylactic agents were evaluated using a systematicliterature review. Forty-two studies met eligibility criteria, of which23 included patients who had TKR and 25 included patients whohad THR. The following statements summarize therecommendations for chemoprophylaxis:

Patients at standard risk of both PE and major bleeding shouldbe considered for aspirin, low-molecular-weight heparin (LMWH),synthetic pentasaccharides, or warfarin with an internationalnormalized ratio (INR) goal of ≤2.0.

Patients at elevated (above standard) risk of PE and at standardrisk of major bleeding should be considered for LMWH, syntheticpentasaccharides, or warfarin with an INR goal of ≤2.0.

Patients at standard risk of PE and at elevated (above standard)risk of major bleeding should be considered for aspirin, warfarinwith an INR goal of ≤2.0, or none.

Patients at elevated (above standard) risk of both PE and majorbleeding should be considered for aspirin, warfarin with an INRgoal of ≤2.0, or none.

Overview and Rationale

This clinical practice guideline wasapproved by the American Academyof Orthopaedic Surgeons (AAOS) onMay 18, 2007. It is based on a sys-tematic review of published studieson the management of adult patientsundergoing total hip replacement(THR) or total knee replacement

(TKR) aimed specifically at prevent-ing symptomatic pulmonary embo-lism (PE). In addition to providingpractice recommendations, thisguideline also highlights gaps in theliterature and areas that require fu-ture research.

The purpose of this clinical practiceguideline is to help improve treatmentbased on the current best evidence. Cur-

Norman A. Johanson, MD

Paul F. Lachiewicz, MD

Jay R. Lieberman, MD

Paul A. Lotke, MD

Javad Parvizi, MD

Vincent Pellegrini, MD

Theodore A. Stringer, MD

Paul Tornetta III, MD

Robert H. Haralson III, MD,MBA

William C. Watters III, MD

This clinical practice guideline wasapproved by the American Academy ofOrthopaedic Surgeons. Approximatelyfour AAOS Clinical Practice Guidelineswill be developed per year, withsummaries regularly presented in theJournal of the American Academy ofOrthopaedic Surgeons. This guidelinesummary is first of the series.

J Am Acad Orthop Surg 2009;17:183-196

Copyright 2009 by the AmericanAcademy of Orthopaedic Surgeons.

AAOS Clinical Practice Guideline Summary

March 2009, Vol 17, No 3 183

rent evidence-based practice standardsdemand that physicians use the bestavailable evidence in their clinical de-cision making. To assist in this, this clin-ical practice guideline consists of a se-ries of systematic reviews of theavailable literature regarding the pre-vention of PE in patients undergoingTHR or TKR. These systematic reviewswere conducted on August 28, 2006,

for pertinent articles published between2000 and 2006 initially, and subse-quently extended back to publicationsthat included patient populations en-rolled after the start of 1996. The re-sults of the reviews show where thereis good evidence, where evidence islacking, and what topics future researchmust target to improve the treatment ofpatients with osteoarthritis of the knee.

The PE Guideline Work Group, withthe assistance of an Evidence ReviewTeam (ERT) from the Center for Clin-ical Evidence Synthesis at Tufts Med-ical Center, systematically reviewed theavailable literature and subsequentlywrote the following recommendationsbased on a rigorous, standardized pro-cess. Of the 14 recommendations devel-oped, only recommendations 3.3.1,

Dr. Johanson is Professor and Chair, Department of Orthopaedic Surgery, Drexel University College of Medicine, Philadelphia, PA.Dr. Lachiewicz is Professor of Orthopaedics, University of North Carolina School of Medicine, Chapel Hill, NC. Dr. Lieberman isDirector, New England Musculoskeletal Institute, and Professor and Chairman, Department of Orthopaedic Surgery, University ofConnecticut Health Center, Farmington, CT. Dr. Lotke is Professor, Department of Orthopaedic Surgery, Hospital of the University ofPennsylvania, Philadelphia. Dr. Parvizi is Director of Clinical Research, Rothman Institute at Thomas Jefferson University Hospital,Philadelphia. Dr. Pellegrini is James Lawrence Kernan Professor and Chair, Department of Orthopaedics, University of MarylandMedical Center, Baltimore, MD. Dr. Stringer is Orthopaedic Surgeon, Colorado Springs Orthopaedic Group, Colorado Springs, CO.Dr. Tornetta is Professor, Vice Chairman, and Residency Program Director, Department of Orthopaedic Surgery, Boston UniversitySchool of Medicine, and Director of Orthopaedic Trauma, Boston Medical Center, Boston, MA. Dr. Haralson is Executive Director ofMedical Affairs, American Academy of Orthopaedic Surgeons, Rosemont, IL. Dr. Watters is Orthopaedic Surgeon, Bone and JointClinic of Houston, Houston, TX.

Dr. Johanson or a member of his immediate family is affiliated with the publications Journal of Arthroplasty and Journal of Bone andJoint Surgery American; has received royalties from Exactech, Inc; serves as a paid consultant to or is an employee of Stelkast; andhas received research or institutional support from DePuy, Exactech, IsoTis Orthobiologics, and Zimmer. Dr. Lachiewicz or a memberof his immediate family serves as a board member, owner, officer, or committee member of the Hip Society and the SouthernOrthopaedic Association; is affiliated with the publication Journal of Orthopaedic Advances; has received royalties from Innomed; is amember of a speakers’ bureau or has made paid presentations on behalf of Covidien and DJO Global; serves as an unpaidconsultant to Zimmer; and has received research or institutional support from Zimmer. Dr. Lieberman or a member of his immediatefamily serves as a board member, owner, officer, or committee member of the American Association of Hip and Knee Surgeons; isaffiliated with the publications Journal of Arthroplasty, Seminars in Arthroplasty, and the Journal of the American Academy ofOrthopaedic Surgeons; serves as a paid consultant to or is an employee of DePuy, Boehringer Ingelheim, Bayer HealthCare, andScios; has received research or institutional support from Arthrex, DePuy, Tornier, Medtronics, Amgen, and Stryker; and has receivednonincome support (such as equipment or services), commercially derived honoraria, or other non–research-related funding (such aspaid travel) from the American Academy of Orthopaedic Surgeons, DePuy, Boehringer Ingelheim, Bayer HealthCare, and Amgen.Dr. Lotke or a member of his immediate family serves as a paid consultant to or is an employee of Bayer and DePuy; is affiliated withthe publications Knee, American Journal of Orthopaedics, and Journal of Arthroplasty; and has received nonincome support (such asequipment or services), commercially derived honoraria, or other non-research-related funding (such as paid travel) from DePuy.Dr. Parvizi or a member of his immediate family serves as a board member, owner, officer, or committee member of SmartTech; isaffiliated with the publications American Journal of Orthopaedics, Current Opinion in Orthopaedics, International Orthopaedics,Journal of Bone and Joint Surgery American and British, Journal of the American Academy of Orthopaedic Surgeons, andOrthopedics Today, and with the publisher SLACK; serves as a paid consultant to or is an employee of Stryker, and has receivedresearch or institutional support from Stryker. Dr. Pellegrini or a member of his immediate family serves as a board member, owner,officer, or committee member of the American Orthopaedic Association, the Association of Bone and Joint Surgeons, the Hip Society,the ACGME Residency Review Committee, the Kernan Orthopaedic and Rehabilitation Hospital, the Maryland Orthopaedic Association,the Knee Society, and the AAMC Council of Academic Specialties Administrative Board; is affiliated with the publications ClinicalOrthopaedics and Related Research, and Journal of Bone and Joint Surgery American; has received royalties form DePuy; is amember of a speakers’ bureau or has made paid presentations on behalf of DePuy; serves as an unpaid consultant of NationalInstitutes of Health, Province of Ontario, Canada; and has received research or institutional support from the Journal of Bone and JointSurgery American, AO, DePuy, Johnson & Johnson, National Institutes of Health, Novartis, Smith & Nephew, Stryker, and Synthes.Dr. Tornetta or a member of his immediate family is affiliated with the publication Orthopedics Today and the publisher Wolters KluwerHealth; has received royalties from Smith & Nephew; serves as a paid consultant to or is an employee of Smith & Nephew; hasreceived research or institutional support from Smith & Nephew; and has stock or stock options held in Exploramed. Dr. Haralson or amember of his immediate family serves as a paid consultant to or is an employee of Medtronic Sofamor Danek, and has stock or stockoptions held in Allmeds. Dr. Watters or a member of his immediate family serves as a board member, owner, officer, or committeemember of the Bone and Joint Decade, the North American Spine Society, Intrinsic Therapeutics, the Work Loss Data Institute, andthe American Board of Spine Surgery; serves as a paid consultant to or is an employee of Blackstone Medical, Medtronic SofamorDanek, Stryker, Intrinsic Therapeutics, and McKessen Health Care Solutions; and has stock or stock options held in IntrinsicTherapeutics. Neither Dr. Stringer nor a member of his immediate family has received anything of value from or owns stock in acommercial company or institution related directly or indirectly to the subject of this article.

Prevention of Symptomatic Pulmonary Embolism in Patients Undergoing Total Hip or Knee Arthroplasty

184 Journal of the American Academy of Orthopaedic Surgeons

3.3.2, 3.3.3, and 3.3.4 are based on thesystematic review of the literature. Theother recommendations contained inthis guideline are based on consensusdevelopment methods only.

Musculoskeletal care is provided inmany different settings by many dif-ferent providers. The AAOS Re-search Department with the collabo-ration of a Physician Workgrouphave created this guideline as an edu-cational tool to guide qualified phy-sicians through a series of treatmentdecisions in an effort to improve thequality and efficiency of care. By theintroduction of new statistical meth-odology, which is discussed in thedata summaries, we have movedahead from previous efforts and havecreated state-of-the-art guidelinerecommendations. This guidelineshould not be construed as includingall proper methods of care or exclud-ing methods of care reasonably di-rected to obtaining the same results.The ultimate judgment regarding anyspecific procedure or treatment mustbe made in light of all circumstancespresented by the patient and theneeds and resources particular to thelocality or institution.

These evidence-based ClinicalPractice Guidelines, approximatelyfour developed per year, will be regu-larly presented as summaries in theJournal of the American Academy ofOrthopaedic Surgeons. They eachrepresent work by AAOS staff andvolunteer committee members of theEvidence-Based Practice Committeeand the Guidelines and TechnologyOversight Committee. While we rec-ognize that the literature is imperfectand thus any guideline must be sup-plemented by experience, principlesof good care, and other sources ofinformation for decision support,these guidelines represent the bestsource of defense, based on thebroadest literature search possible.

These guidelines also represent thedefinition of quality orthopaedicpractice from an evidence-basedview. There will be measureable im-provements in patient care qualitystandards as evidence emerges and issummarized as future guidelines.

Potential Harms andContraindications

Most treatments are associated withsome known risks, especially inva-sive and surgical treatments. In addi-tion, contraindications vary widelybased on the treatment administered.Therefore, discussion of availabletreatments and procedures applica-ble to the individual patient rely onmutual communication between thepatient and physician.

Methods

The methods used to develop thisclinical practice guideline were de-signed to combat bias, enhancetransparency, and promote reproduc-ibility. Their purpose is to allow in-terested readers the ability to inspectall of the information the Work-group used to reach all of its deci-sions, and to verify that these deci-sions are in accord with the bestavailable evidence. The draft of thisguideline was subject to peer reviewand public commentary, and it wasapproved by the AAOS’s Evidence-Based Practice Committee; Guide-lines and Technology Committee;Council on Research, Quality Assess-ment and Technology; and Board ofDirectors. The methods used to pre-pare this guideline as well as the ref-erences to the literature are detailedin the full clinical practice guideline,which is available at http://www.aaos.org/research/guidelines/PE_guideline.pdf.

Rating the Quality ofEvidence

The quality of evidence was rated us-ing an evidence hierarchy for each offour different study types: therapeu-tic, prognostic, diagnostic, and eco-nomic or decision modeling. Thesehierarchies were predefined by theAAOS and appear on the AAOSWebsite at www2.aaos.org/aaos/archives/bulletin/feb03/fline1.htm.

Grading theRecommendations

Each guideline recommendation wasgraded using the following system:

A: Good evidence (level I studieswith consistent finding) for recom-mending intervention.

B: Fair evidence (level II or III stud-ies with consistent findings) for rec-ommending intervention.

C: Poor quality evidence (level IVor V) for recommending interven-tion.

Recommendations

Of the 14 recommendations listedbelow, only recommendations 3.3.1,3.3.2, 3.3.3, and 3.3.4 are based onthe systematic review of the litera-ture conducted between August 2006and March 2007 by the Center forClinical Evidence Synthesis at TuftsMedical Center. The other recom-mendations contained in this guide-line are based on consensus develop-ment methods only.

Recommendation 1:Preoperative Care

Recommendation 1.1All patients should be assessed pre-operatively for elevated risk (greaterthan standard risk) of PE. The fol-lowing patients are examples of

Norman A. Johanson, MD, et al

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those considered to be at elevatedrisk:• Hypercoagulable states• Previous documented PE

Level of Evidence: IIIGrade of Recommendation: B

Rationale forRecommendation 1.1The risk of PE differs among differ-ent patients; however, there is cur-rently no satisfactory evidence-basedrisk stratification system. There havebeen studies suggesting that the riskof PE is elevated in patients with pre-vious history of cancer, thromboem-bolism, and hypercoagulable statessuch as polycythemia, as well as inspinal cord injury patients and multi-trauma patients.1-3 It is also plausiblethat some patients may have geneticpredisposition for development ofPE.4,5 Currently no specific labora-tory test can reliably identify patientsat elevated risk of PE. Therefore,careful history taking and physicalexamination in combination withclinical judgment, which integratesknowledge of specific risk factorswith the patient’s clinical status, isthe cornerstone of PE risk manage-ment for patients undergoing THRor TKR.

The identification of patients at el-evated risk for PE is important in theselection process of appropriatethromboprophylactic regimens (seeRecommendation 3.3).

Recommendation 1.2All patients should be assessed pre-operatively for elevated risk (greaterthan standard risk) of major bleed-ing. Patients with the following con-ditions are examples of those consid-ered to be at elevated risk:• History of a bleeding disorder• History of recent gastrointestinal

bleed• History of recent hemorrhagic

strokeLevel of Evidence: III

Grade of Recommendation: CNB: This Grade of Recommenda-

tion was reduced from B to C be-cause of the lack of consistent evi-dence in the literature on riskstratification of patient populations.

Rationale forRecommendation 1.2The selection of a thromboprophy-lactic regimen should aim for a bal-ance between efficacy and safety. Allchemoprophylaxis agents, by virtueof their action, are associated withbleeding. Some agents may result ina higher incidence of bleeding fol-lowing total joint arthroplasty,6 al-though the differences in bleedingrates with the currently used agentsare unclear (see Recommendation3.3).7-10 Patients on aspirin or me-chanical prophylaxis alone, on theother hand, may have lower bleedingrates.6,11-13 Not only might the bleed-ing potential of different prophylac-tic agents vary, there may also bevarying bleeding tendencies amongindividuals that may affect the bleed-ing risk with surgery.14 The intentionof this recommendation is to identifypatients who may be at elevated riskof major bleeding after THR orTKR. The type of prophylacticagent, the duration of prophylaxis,and the intensity of anticoagulationneeds to be modulated based on theperceived bleeding risk in an individ-ual patient. Some factors that mayplace a patient at an elevated risk ofbleeding include a history of uncon-trolled bleeding, and a known coagu-lation factor deficiency, a recent his-tory of gastrointestinal bleeding, andrecent hemorrhagic stroke. This rec-ommendation highlights the centralimportance of careful history takingand physical examination for thepurpose of risk stratification forbleeding. Although routine serologi-cal tests to screen patients for poten-tial bleeding problems are not indi-cated, they may be useful in patients

for whom there is a high level of sus-picion of a predisposition for bleed-ing.

Recommendation 1.3Patients with known contraindica-tions to anticoagulation should beconsidered for vena cava filter place-ment.

Level of Evidence: VGrade of Recommendation: C

Rationale forRecommendation 1.3A vena cava filter may reduce therisk of PE in a nonanticoagulated pa-tient.15 The assumed ability of a filterto stop emboli originating in thelower extremities underlies the ex-pected clinical usefulness of filters inselected total hip and knee patients.The very low level of evidence andstrength of recommendation reflectthe poor evidence base behind thisdecision-making process. The needfor a filter is most commonly en-countered when there is elevated pre-operative risk of PE and a knowncontraindication for chemoprophy-laxis, or if chemoprophylaxis be-comes contraindicated in an elevatedrisk patient during the postoperativecourse. Similarly, if a patient with aknown contraindication to chemo-prophylaxis changes from standardto elevated PE risk in the postopera-tive period, a vena cava filter maybe considered. Finally, in patientsthought to be at elevated risk of ma-jor bleeding who develop sympto-matic postoperative PE, a filtershould be considered.

Recommendation 2:Intraoperative CareRecommendation 2.1Patients should be considered for in-traoperative and/or immediate post-operative mechanical prophylaxis.

Level of Evidence: III

Grade of Recommendation: B



Rationale forRecommendation 2.1Thrombogenesis activation beginsduring total hip arthroplasty througha variety of mechanisms. These in-clude venous stasis due to anesthesia,immobilization, intimal injury (dueto kinking of the femoral vein withdislocation of the hip and femoralcanal preparation) and activation ofthe clotting cascade (by a variety ofmechanisms).16,17 Mechanical venouscompression ameliorates some of thefactors involved in thrombogenesisand therefore should be consideredintraoperatively, if practical and ifthere are no contraindications to useof the device.18,19 For THR, mechani-cal prophylaxis can easily be used onthe nonsurgical limb, and there aresterile thigh-calf and calf-only pneu-matic devices that can be used on thesurgical limb.18-20 In observationalstudies, the use of these devices (usu-ally in combination with regional an-esthesia and aspirin chemoprophy-laxis) has been shown to result in alow rate of symptomatic PE.16,19 Al-ternatively, these pneumatic devicesmay be placed on the lower extremi-ties in the recovery room after theprocedure is completed.21 There is avariety of mechanical devices avail-able, including thigh-calf, calf-only,and foot pumps.22 There are no pro-spective, randomized studies com-paring the efficacy of these devices inthe prevention of symptomatic PE.

The activation of thrombogenesis inTKR patients has been less well stud-ied. Intraoperative mechanical compres-sion can be used on the nonsurgicallimb, but there is no effective sterile de-vice for use on the surgical limb, espe-cially if a tourniquet is used. Most stud-ies begin use of a mechanical device onthe surgical limb postoperatively in therecovery room.23-26

Recommendation 2.2In consultation with the anesthesiol-ogist, patients should be considered

for regional anesthesia.Level of Evidence: IVGrade of Recommendation: C

Rationale forRecommendation 2.2Regional anesthesia (spinal, epidural orhypotensive epidural with cardiac mon-itoring) has been recommended overgeneral endotracheal anesthesia forTHR and TKR patients.16,17,27,28 Re-gional anesthesia has been shown todecrease venous flow less and resultin fewer pulmonary complications.However, there is only circumstantialevidence that regional anesthesia, aspart of a multimodal prophylaxisprotocol, reduces the prevalence ofsymptomatic and fatal PE.18,19,27

The choice of anesthetic techniquefor these patients is based on multi-ple factors, including thromboembo-lism prophylaxis. There should beclose consultation between the sur-geon and the anesthesiologist for theanesthetic technique.

Recommendation 3:Postoperative/InpatientCare

Recommendation 3.1Postoperatively, patients should beconsidered for continued mechanicalprophylaxis until discharge to home.

Level of Evidence: IVGrade of Recommendation: C

Rationale forRecommendation 3.1Unless contraindicated, mechanicalcompression should be used for bothTHR16,18-21,25 and TKR.23-26 for pa-tients in the recovery room and dur-ing the hospital stay. The optimalnumber of hours daily that mechani-cal compression should be used isunknown. A team approach involv-ing surgeons, nurses, aides, and ther-apists is required to optimize theamount of time the devices are onthe patients’ limbs. Many patientsare transferred to “same site” reha-

bilitation floors or hospital servicesearly postoperatively. It is recom-mended that mechanical prophylaxiscontinue at these locations if practi-cal.

One prospective randomized studyshowed that rapid-inflation, asym-metric calf compression was superiorto circumferential calf compressionin total knee patients.23 For total hippatients, the postoperative devicesstudied included thigh-calf com-pression,18,19 rapid-inflation calf,21,25

other calf compression, and footpumps, usually part of a multimodalprophylaxis protocol. Patient prefer-ences and comfort should be takeninto account, when feasible. Onestudy reported a high prevalence ofpatient intolerance and discontinua-tion of foot pumps postoperativelyafter THR.12

Recommendation 3.2Postoperatively, patients should bemobilized as soon as feasible to thefull extent of medical safety andcomfort.

Level of Evidence: VGrade of Recommendation: C

Rationale forRecommendation 3.2At a minimum, patients should betaught to actively dorsiflex and plan-tar flex the ankle and toes. This exer-cise should be performed in sets of10 to 20 every half hour when thepatient is awake. A plan for painmanagement that allows control forthe patient to be out of bed and sub-sequently ambulate should be inplace before surgery. All patientsshould be out of bed to a sittingchair several times a day for severalhours at a time to encourage deepbreathing and avoid recumbency. Allefforts should be made to have thepatient stand and ambulate withinthe restrictions placed by the surgicalsurgeon. Practices should be in placeto ensure that appropriate physical


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therapy, ambulatory assistance, andsupport are provided by the firstpostoperative day. Patients who aretreated with epidural catheters post-operatively should also be out of bedto a chair as soon as feasible. Stand-ing and ambulation should begin forthese patients when they are physi-cally capable of it. During hospital-ization, when patients are not am-bulating, mechanical prophylaxisshould remain in place at all times,even when the patient is out of bed.

Recommendation 3.3Chemoprophylaxis of patients un-dergoing hip or knee replacement.

Recommendation 3.3.1 (based onsystematic review)Patients at standard risk of both PEand major bleeding should be consid-ered for one of the chemoprophylacticagents evaluated in this guideline, in-cluding (in alphabetical order):

a. Aspirin, 325 mg 2×/d (reduce to81 mg 1×/d if gastrointestinal symp-toms develop), starting the day ofsurgery, for 6 weeks.

b. LMWH, dose per package in-sert, starting 12 to 24 hours postop-eratively (or after an indwelling epi-dural catheter has been removed),for 7 to 12 days. (NB: The LMWHshave not been sufficiently evaluatedfor longer periods to allow recom-mendation beyond this period.)

c. Synthetic pentasaccharides, doseper package insert, starting 12 to 24hours postoperatively (or after an in-dwelling epidural catheter has beenremoved), for 7 to 12 days. (NB: Thesynthetic pentasaccharides have notbeen sufficiently evaluated for longerperiods to allow recommendationbeyond this period.)

d. Warfarin, with an internationalnormalized ratio (INR) goal of ≤2.0,starting either the night before or thenight after surgery, for 2 to 6 weeks.


(choice of prophylactic agent), C(dosage and timing)

NB: The Grade of Recommenda-tion was reduced from B to C fordosage and timing because of thelack of consistent evidence in the lit-erature defining a clearly superior re-gime.

Rationale forRecommendation 3.3.1Patients with standard risk of PE andstandard risk of major bleeding rep-resent the majority of total joint ar-throplasty patients. As noted in theintroduction to this guideline ortho-paedic surgery carries with it ahigher level of risk for thromboem-bolic complications than for generalsurgical or medical patients. There-fore the term “standard” should beunderstood as a relative term specifi-cally for hip and knee replacement.Since the incidence rates of sympto-matic PE are low, it is not possible tomake definitive recommendations onthe occurrence of PE alone. To deter-mine differences in current chemo-prophylactic regimens, we wouldneed at least 25,000 and 150,000 pa-tients, respectively (calculated usinga relative risk of 0.5 for the efficacyof prophylaxis). These low incidencerates of PE and fatal PE mean thatwe must look more closely at the op-posite side of the risk equation andfully assess the adverse effects (pri-marily bleeding) that result from ourrecommendations.

The bleeding risk from chemopro-phylactic agents may rise with in-creased effectiveness in reducingdeep vein thrombosis (DVT).6 Theincidence of major bleeding is <1%in patients without chemoprophy-laxis and may be as high as about3% to 5% in patients given chemo-prophylactic agents.29 Precise esti-mates of the true risk of bleeding aredifficult to obtain since the defini-tions of major bleeds vary amongdifferent studies. In general, the defi-

nitions of a major bleed include life-threatening, intraocular, or intracere-bral bleeds, or a bleed requiringmore than a specified number oftransfusions. Furthermore, most ofthe prospective data from drug com-parison studies use selected popula-tions, which exclude patients withprior gastrointestinal bleeds andnoncompliant or frail patients. Alsopatients may not have been includedwithin the major bleed definitions ifthey had bleeding events that did notimmediately affect surgical out-comes. In general, clinical outcomesin patients with a defined majorbleed or in the spectrum of patientswith lesser bleeding have not beenwell studied.

The present recommendations re-flect the Work Group’s concernsabout increased bleeding associatedwith the use of chemoprophylacticagents without a demonstrated re-duction in PE. The duration for theadministration of chemoprophylacticagents has not been clearly estab-lished. The older literature notes thatmost postoperative PEs occurredwithin the first 6 weeks.30-34 There-fore, many regimens were establishedto conform to that experience. Somereports on the heparinlike drugs,show that it is not necessary to pro-long the administration beyond thefirst 8 to 12 days.35 The WorkGroup’s recommendations reflectthese practices.

Combinations of agents may alsobe considered, such as a short courseof LMWH followed by aspirin.However, there is no definitive evi-dence that demonstrates a reductionin PE using any of these regimens.

Recommendation 3.2, which rec-ommends that patients should bemobilized rapidly after surgery un-less contraindicated, should beviewed as universally applicable, re-gardless of choice of chemicalchemoprophylaxis. Mechanical de-vices have no inherent bleeding risk;



however, their effectiveness in reduc-ing the incidence of PE has not beendefinitively demonstrated. Therefore,they remain an adjunct in the arma-mentarium for prophylaxis unlessthere is a contraindication forchemoprophylaxis, in which casethey become the primary means ofprevention.

Recommendation 3.3.2 (based onsystematic review)Patients at elevated (above standard)risk of PE and at standard risk ofmajor bleeding should be consideredfor one of the following chemopro-phylactic agents (in alphabetical or-der):

a. LMWH, dose per package in-sert, starting 12 to 24 hours postop-eratively (or after an indwelling epi-dural catheter has been removed),for 7 to 12 days. (NB: The LMWHshave not been sufficiently evaluatedfor longer periods to allow recom-mendation beyond this period.)

b. Synthetic pentasaccharides, doseper package insert, starting 12 to 24hours postoperatively (or after an in-dwelling epidural catheter has beenremoved), for 7 to 12 days. (NB: Thesynthetic pentasaccharides have notbeen sufficiently evaluated for longerperiods to allow recommendationbeyond this period.)

c. Warfarin, with an INR goal of≤2.0, starting either the night beforeor the night after surgery, for 2 to 6weeks.


(choice of prophylactic agent), C(dosage and timing)

NB: The grade of Recommenda-tion was reduced from B to C fordosage and timing because of thelack of consistent evidence in the lit-erature on risk stratification of pa-tient populations. No studies cur-rently include patients at elevatedrisk of major bleeding in studygroups.

Rationale forRecommendation 3.3.2Warfarin (INR ≤ 2.0), LMWH, or asynthetic pentasaccharide is recom-mended as chemoprophylaxis for pa-tients known or suspected to be atincreased risk of PE after total hip orknee arthroplasty. In this clinical set-ting, the customary risk-benefit bal-ance between therapeutic anticoagu-lation and bleeding risk is tipped infavor of the most effective prophy-laxis while acknowledging a poten-tially higher bleeding risk as atradeoff for optimal efficacy in pre-vention of PE.

The data presented in Figures 1and 2 do not demonstrate differenti-ation of effectiveness among any ofthe chemoprophylactic agents in theprevention of PE. This is in clearcontrast to the results of DVT ori-ented studies, where there is evidenceto support distinctions. For example,the efficacy in prevention of DVThas been shown, in declining order,for the synthetic pentasaccharide(fondaparinux), LMWH (enoxapar-in, dalteparin),7,36-38 and low intensitywarfarin (INR 2.0).39

Although the incidence of majorbleeding after THR appears to behigher than TKR (Figures 3 and 4),the clinical tolerance for majorbleeding may be less after TKR ow-ing to the more superficial nature ofthe knee and the tenuous characterof its soft-tissue envelope. Therefore,a higher level of concern for postop-erative bleeding in TKR is prevalentamong most surgeons in light of atheoretically higher potential for ableed to compromise the clinical out-come.

In addition to the use of chemo-prophylactic agents it is prudent toemploy other adjunctive measures asoutlined in Recommendations 2.1,2.2, and 3.1.

Recommendation 3.3.3 (based onsystematic review)Patients at standard risk of PE and atelevated (above standard) risk of ma-jor bleeding should be considered forone of the following chemoprophy-lactic agents (in alphabetical order):


b. Warfarin, with an INR goal of≤2.0, starting either the night beforeor the night after surgery, for 2 to 6weeks.

c. None.Level of Evidence: IIIGrade of Recommendation: CNB: This Grade of Recommenda-

tion was reduced from B to C be-cause of the lack of consistent evi-dence in the literature on riskstratification of patient populations.No studies currently include patientsat elevated risk of major bleeding instudy groups.

Patients who are at standard riskof PE but at an elevated risk of ma-jor bleeding are relatively uncom-mon. Examples of this includethrombocytopenia, bone marrowsuppression, known hemophilia orother defined coagulation defects, re-cent radiation, and chemotherapy.The management of these patientsshould be individualized (perhaps inassociation with a hematologist).The first priority is to correct theclotting defect, if possible, beforesurgery, using transfusions of clot-ting factors, platelets, or frozenplasma. The use of a chemoprophy-lactic agent in a patient with aknown diminished ability to clotmust be considered judiciously, asthere is currently no evidence base toassist in this decision.



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Recommendation 3.3.4 (based onsystematic review)Patients at elevated (above standard)risk of both PE and major bleedingshould be considered for one of thefollowing chemoprophylactic agents(in alphabetical order):


b. Warfarin, with an INR goal of≤2.0, starting either the night before

or the night after surgery, for 2 to 6weeks.

c. None.Level of Evidence: IIIGrade of Recommendation: CNB: This Grade of Recommenda-

tion was reduced from B to C be-cause of the lack of consistent evi-dence in the literature on riskstratification of patient populations.No studies currently include patientsat elevated risk of major bleedingand PE in study groups.

Rationale forRecommendation 3.3.4In the setting of elevated risk of bothPE and major bleeding (above stan-dard risk), the selection of the mostappropriate prophylactic regimen isdependent on the clinical judgmentof the surgeon and medical consul-tants. The final judgment is the resultof integrating the knowledge of theseverity of existent risk factors forPE and bleeding with the patient’scurrent status. Although the recom-

Summary pulmonary embolism, pulmonary embolism death, and total death rates for patients after hip arthroplastyreceiving different prophylaxis regimens. Dotted vertical lines represent 0.2% increments. Where there are ranges oftotal n’s (events), one or more studies were unclear as to the total number of events (eg, whether pulmonaryembolisms were confirmed or not, whether deaths were due to confirmed pulmonary embolism or not). Multiplemedians or averages represent the range of estimates. These approaches do not adequately account for theheterogeneity of interventions, follow-up duration, quality, applicability, etc. These analyses do not include studies thatexcluded events that occurred in-hospital. PE = pulmonary embolism. All systemic = low-molecular-weight heparin(LMWH) + warfarin + fondaparinux studies combined (in addition to studies that combined these interventions).LMWH = LMWH alone and combination LMWH and mechanical; warfarin = warfarin alone and combination warfarinand mechanical; mechanical/aspirin = either mechanical alone, aspirin alone, or mechanical and aspirin; aspirin =aspirin and combination aspirin and mechanical. I

__I = median rate among studies (only determined if 3 cohorts of

patients), • = simple average (total n/total N) and “exact” estimate of CI of that average, ▲ = random effects estimateand CI using Bayesian methodology, ■ = random effects estimate and CI using logit of proportions methodology.(Reprinted from Lachiewicz PF: Prevention of symptomatic pulmonary embolism in patients undergoing total hip andknee arthroplasty: Clinical guideline of the American Academy of Orthopaedic Surgeons. Instr Course Lect2009;58:795-804.)

Figure 1



mendations 3.3.3 and 3.3.4 regard-ing chemoprophylaxis contain iden-tical agents, the range of options(from warfarin to no chemoprophy-laxis) is wide. Particularly for pa-tients at elevated risk of both PE andmajor bleeding, it is very importantthat the physician has as accurate anassessment as possible of the actuallikelihood of a life-threatening PE.Aspirin, with its attendant very lowrisk of bleeding, and warfarin, whichcan be dosed to lower INRs in high-

risk bleeding situations, are theagents recommended if chemopro-phylaxis is deemed necessary.


Recommendation 3.4Routine screening for DVT or PEpostoperatively in asymptomatic pa-tients is not recommended.


Rationale forRecommendation 3.4Specific recommendation is madeagainst routine surveillance forvenous thromboembolism after THRor TKR. There is neither a suffi-ciently sensitive noninvasive screen-ing tool nor a clearly establishedperiod of risk for venous throm-boembolism as to make routine

Summary pulmonary embolism, pulmonary embolism death, and total death rates for patients after knee arthroplastyreceiving different prophylaxis regimens. Dotted vertical lines represent 0.2% increments. Where there are ranges oftotal n’s (events), one or more studies were unclear as to the total number of events (eg, whether pulmonaryembolisms were confirmed or not, whether deaths were due to confirmed pulmonary embolism or not). Multiplemedians or averages represent the range of estimates. These approaches do not adequately account for theheterogeneity of interventions, follow-up duration, quality, applicability, etc. These analyses do not include studies thatexcluded events that occurred in-hospital. PE = pulmonary embolism. All systemic = low-molecular-weight heparin(LMWH) + warfarin + fondaparinux studies combined (in addition to studies that combined these interventions).LMWH = LMWH alone and combination LMWH and mechanical; warfarin = warfarin alone and combination warfarinand mechanical; mechanical/aspirin = either mechanical alone, aspirin alone, or mechanical and aspirin; aspirin =aspirin and combination aspirin and mechanical. I

__I = median rate among studies (only determined if 3 cohorts of

patients), • = simple average (total n/total N) and “exact” estimate of CI of that average, ▲ = random effects estimateand CI using Bayesian methodology, ■ = random effects estimate and CI using logit of proportions methodology.(Reprinted from Lachiewicz PF: Prevention of symptomatic pulmonary embolism in patients undergoing total hip andknee arthroplasty: Clinical guideline of the American Academy of Orthopaedic Surgeons. Instr Course Lect2009;58:795-804.)

Figure 2


March 2009, Vol 17, No 3 191

screening reliably predictive or cost-effective in preventing PE.

The premise that routine screeningis an effective strategy to prevent PEis predicated upon the hypothesisthat secondary prophylaxis, namelyprevention of propagation and em-bolization of existing thrombi, is avalid approach to reducing the in-

cidence of PE. One study of morethan 3,000 patients with 6-monthfollow-up of readmission for symp-tomatic proximal DVT or PE dem-onstrated a readmission rate in pa-tients discharged without continuedanticoagulation on the basis of nega-tive screening contrast venographynearly 8 times greater than patients

who received 6 weeks of warfarinbased on a positive screening veno-gram or empiric continuation of pro-phylaxis.40,41

Other imaging modalities have beensuggested for routine screening. Duplexultrasound is highly operator depen-dent, test performance is variable frominstitution to institution, and the test is

Major bleeding and death from bleeding rates for patients after hip arthroplasty receiving different prophylaxisregimens. Dotted vertical lines represent 0.2% increments. Where there are ranges of total n’s (events), one or morestudies were unclear as to the total number of events (eg, whether pulmonary embolisms were confirmed or not,whether deaths were due to confirmed pulmonary embolism or not). Multiple medians or averages represent the rangeof estimates. These approaches do not adequately account for the heterogeneity of interventions, follow-up duration,quality, applicability, etc. These analyses do not include studies that excluded events that occurred in-hospital. PE =pulmonary embolism. All systemic = low-molecular-weight heparin (LMWH) + warfarin + fondaparinux studiescombined (in addition to studies that combined these interventions). LMWH = LMWH alone and combination LMWHand mechanical; warfarin = warfarin alone and combination warfarin and mechanical; mechanical/aspirin = eithermechanical alone, aspirin alone, or mechanical and aspirin; aspirin= aspirin and combination aspirin and mechanical.I__I = median rate among studies (only determined if 3 cohorts of patients), • = simple average (total n/total N) and“exact” estimate of CI of that average, ▲ = random effects estimate and CI using Bayesian methodology, ■ = randomeffects estimate and CI using logit of proportions methodology. (Reprinted from Lachiewicz PF: Prevention ofsymptomatic pulmonary embolism in patients undergoing total hip and knee arthroplasty: Clinical guideline of theAmerican Academy of Orthopaedic Surgeons. Instr Course Lect 2009;58:795-804.)

Figure 3



not sensitive to thrombus identificationdistal to the level of the adductor canaland in the pelvis. Magnetic resonancevenography has been shown to be sen-sitive in imaging asymptomatic pelvicthrombi but remains costly and cum-bersome to repeat on a regular basis.

Routine screening by genetic predis-position or identification of a single se-rum clotting factor has yet to demon-

strate a strong correlation with venousthromboembolic disease after THR orTKR.

Recommendation 4:Discharge to Home

Recommendation 4.1Patients should be encouraged toprogressively increase mobility after

discharge to home.Level of Evidence: VGrade of Recommendation: C

Recommendation 4.2Patients should be educated about thecommon symptoms of DVT and PE.

Level of Evidence: VGrade of Recommendation: B

Major bleeding and death from bleeding rates for patients after hip arthroplasty receiving different prophylaxisregimens. Dotted vertical lines represent 0.2% increments. Where there are ranges of total n’s (events), one or morestudies were unclear as to the total number of events (eg, whether pulmonary embolisms were confirmed or not,whether deaths were due to confirmed pulmonary embolism or not). Multiple medians or averages represent the rangeof estimates. These approaches do not adequately account for the heterogeneity of interventions, follow-up duration,quality, applicability, etc. These analyses do not include studies that excluded events that occurred in-hospital. PE =pulmonary embolism. All systemic = low-molecular-weight heparin (LMWH) + warfarin + fondaparinux studiescombined (in addition to studies that combined these interventions). LMWH = LMWH alone and combination LMWHand mechanical; warfarin = warfarin alone and combination warfarin and mechanical; mechanical/aspirin = eithermechanical alone, aspirin alone, or mechanical and aspirin; aspirin = aspirin and combination aspirin and mechanical.I__I = median rate among studies (only determined if 3 cohorts of patients), • = simple average (total n/total N) and“exact” estimate of CI of that average, ▲ = random effects estimate and CI using Bayesian methodology, ■ = randomeffects estimate and CI using logit of proportions methodology. (Reprinted from Lachiewicz PF: Prevention ofsymptomatic pulmonary embolism in patients undergoing total hip and knee arthroplasty: Clinical guideline of theAmerican Academy of Orthopaedic Surgeons. Instr Course Lect 2009;58:795-804.)

Figure 4


March 2009, Vol 17, No 3 193

NB: The level of evidence is levelV, expert opinion, but the strength ofrecommendation was increased fromC to B because patient education isconsistent with the minimal expectedstandard of care for today’s medicalpractices.

Rationale forRecommendations 4.1 and 4.2During postoperative hospitaliza-tion, the team caring for the patientshould collaborate with physicaltherapy, occupational therapy, anddischarge planning to extend thehospital program to the home envi-ronment. The team should stress ap-propriate range of motion and ap-propriate conditioning programs,and encourage the patients to avoidprolonged immobility.

All patients should be educated re-garding common symptoms of DVTand PE. DVT symptoms are usuallylocalized to site and include: pain,swelling, tenderness and redness ordiscoloration of skin. PE symptomsinclude shortness of breath, rapidpulse, sweating, feeling of apprehen-sion, chest pains worsening withdeep breath, coughing up blood, de-creased blood pressure, and light-headedness.

These recommendations are an ex-tension of the AAOS concept ofpatient-centered care encouragingpatient education as part of the sur-gical process. The presumption isthat patient participation and educa-tion will enhance awareness, im-prove outcomes, and potentially di-minish the risk associated with theprocedure specifically the potentialfor PE-related morbidity and mortal-ity.

Future Research

Appropriately powered studies to de-tect the superiority of any preventivestrategy for PE would be far more

costly than for DVT. ConsequentlyDVT, which occurs much more fre-quently and seems to occur with awider variability among treatmentgroups is a more attractive proxymeasure. But the reduction of DVTdoes not appear to have a significanteffect on the PE rate, and this callsinto question the long-assumed epi-demiologic if not pathophysiologiclink between the two processes. Ad-ditional research, which better de-scribes this relationship, would behelpful.

Postoperative bleeding in andaround the surgical wound is an ex-ample of a complication that may bedirectly caused by prophylaxis. Incontrast to an asymptomatic DVT, apostoperative bleed may lead to evenmore serious problems that signifi-cantly impact the surgical outcome.In this sense the expected benefit ofprevention of one type of surgicalcomplication may be overshadowedby the increased risk of another. Theincidence of major postoperativebleeding should be addressed in amore uniform and standardized fash-ion to facilitate a more reliable com-parison of different studies, andpooling of the results. The functionaloutcomes in patients with majorbleeds should be followed in studiesthat are concerned primarily withthromboembolic events to fairly esti-mate the costs of treatment compli-cations in comparison with those offatal and nonfatal PE.

The issue of PE risk stratificationin the preoperative assessment ofTHR and TKR patients is very im-portant. By developing an evidence-based risk adjustment system it willbe possible to use a more cost-effective individualized prophylacticstrategy. Future research should bedirected at the assessment of the inci-dence of PE following hip or knee re-placement in large unselected popu-lations in which the potential riskfactors are reliably documented.

Large databases such as Medicareand those administered by states mayprovide some assistance, but cur-rently do not include enough specificrisk stratification and outcome vari-ables. Hip and knee replacement reg-istries present real opportunities toenhance the quality and applicabilityof the data. The AAOS has demon-strated a commitment to oversee thedevelopment of a national total jointregistry which would facilitate anefficient and timely approach to pre-venting PE and postoperative bleed-ing complications. Successful imple-mentation of this strategy wouldundoubtedly improve the quality ofcare for our patients and delivervalue to the health care system.

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