![](media/image1.png){width="5.96875in" height="0.41944444444444445in"}

Top of Form

## Complete Summary

#### GUIDELINE TITLE

Imaging after total knee arthroplasty.

#### BIBLIOGRAPHIC SOURCE(S)

Weissman BN, Dalinka MK, Daffner RH, Jacobson JA, Morrison WB, Palmer
WE, Resnik CS, Rubin DA, Schneider R, Schweitzer ME, Seeger LL,
Steinbach LS, Haralson RH III, Expert Panel on Musculoskeletal Imaging.
Imaging after total knee arthroplasty. \[online publication\]. Reston
(VA): American College of Radiology (ACR); 2006. 7 p. \[45 references\]

#### GUIDELINE STATUS

This is the current release of the guideline.

The appropriateness criteria are reviewed annually and updated by the
panels as needed, depending on introduction of new and highly
significant scientific evidence.

### COMPLETE SUMMARY CONTENT

 SCOPE\
 METHODOLOGY - including Rating Scheme and Cost Analysis\
 RECOMMENDATIONS\
 EVIDENCE SUPPORTING THE RECOMMENDATIONS\
 BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS\
 QUALIFYING STATEMENTS\
 IMPLEMENTATION OF THE GUIDELINE\
 INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT
CATEGORIES\
 IDENTIFYING INFORMATION AND AVAILABILITY\
 DISCLAIMER

### SCOPE

#### DISEASE/CONDITION(S)

Complications after total knee arthroplasty (TKA)

#### GUIDELINE CATEGORY

Diagnosis\
Evaluation

#### CLINICAL SPECIALTY

Internal Medicine\
Nuclear Medicine\
Orthopedic Surgery\
Radiology

#### INTENDED USERS

Health Plans\
Hospitals\
Managed Care Organizations\
Physicians\
Utilization Management

#### GUIDELINE OBJECTIVE(S)

To evaluate the appropriateness of initial radiologic examinations after
total knee arthroplasty

#### TARGET POPULATION

Patients after total knee arthroplasty

#### INTERVENTIONS AND PRACTICES CONSIDERED

1.  X-ray, knee

    -   Fluoroscopy

    -   Tunnel views

    -   Anteroposterior/ lateral, standing, and tangential patellar
        views

    -   Arthrography

2.  Computed tomography (CT), knee

3.  Magnetic resonance imaging (MRI), knee

4.  Nuclear medicine (NM)

    -   Bone scan

    -   Gallium scan

    -   Bone and indium-111 white blood cell (WBC) scan

    -   Indium-111 WBC and sulfur colloid scan

    -   Immunoglobulin G (IgG) scan

5.  Fluorodeoxyglucose positron emission tomography (FDG-PET)

6.  Invasive (INV), aspiration, knee

#### MAJOR OUTCOMES CONSIDERED

Utility of radiologic examinations in differential diagnosis

### METHODOLOGY

#### METHODS USED TO COLLECT/SELECT EVIDENCE

Searches of Electronic Databases

#### DESCRIPTION OF METHODS USED TO COLLECT/SELECT THE EVIDENCE

The guideline developer performed literature searches of peer-reviewed
medical journals and the major applicable articles were identified and
collected.

#### NUMBER OF SOURCE DOCUMENTS

The total number of source documents identified as the result of the
literature search is not known.

#### METHODS USED TO ASSESS THE QUALITY AND STRENGTH OF THE EVIDENCE

Weighting According to a Rating Scheme (Scheme Not Given)

#### RATING SCHEME FOR THE STRENGTH OF THE EVIDENCE

Not stated

#### METHODS USED TO ANALYZE THE EVIDENCE

Systematic Review with Evidence Tables

#### DESCRIPTION OF THE METHODS USED TO ANALYZE THE EVIDENCE

One or two topic leaders within a panel assume the responsibility of
developing an evidence table for each clinical condition, based on
analysis of the current literature. These tables serve as a basis for
developing a narrative specific to each clinical condition.

#### METHODS USED TO FORMULATE THE RECOMMENDATIONS

Expert Consensus (Delphi)

#### DESCRIPTION OF METHODS USED TO FORMULATE THE RECOMMENDATIONS

Since data available from existing scientific studies are usually
insufficient for meta-analysis, broad-based consensus techniques are
needed for reaching agreement in the formulation of the appropriateness
criteria. The American College of Radiology (ACR) Appropriateness
Criteria panels use a modified Delphi technique to arrive at consensus.
Serial surveys are conducted by distributing questionnaires to
consolidate expert opinions within each panel. These questionnaires are
distributed to the participants along with the evidence table and
narrative as developed by the topic leader(s). Questionnaires are
completed by participants in their own professional setting without
influence of the other members. Voting is conducted using a scoring
system from 1-9, indicating the least to the most appropriate imaging
examination or therapeutic procedure. The survey results are collected,
tabulated in anonymous fashion, and redistributed after each round. A
maximum of three rounds is conducted and opinions are unified to the
highest degree possible. Eighty percent agreement is considered a
consensus. This modified Delphi technique enables individual, unbiased
expression, is economical, easy to understand, and relatively simple to
conduct.

If consensus cannot be reached by the Delphi technique, the panel is
convened and group consensus techniques are utilized. The strengths and
weaknesses of each test or procedure are discussed and consensus reached
whenever possible. If \"No consensus\" appears in the rating column,
reasons for this decision are added to the comment sections.

#### RATING SCHEME FOR THE STRENGTH OF THE RECOMMENDATIONS

Not applicable

#### COST ANALYSIS

The guideline developers reviewed published cost analyses.

#### METHOD OF GUIDELINE VALIDATION

Internal Peer Review

#### DESCRIPTION OF METHOD OF GUIDELINE VALIDATION

Criteria developed by the Expert Panels are reviewed by the American
College of Radiology (ACR) Committee on Appropriateness Criteria.

### RECOMMENDATIONS

#### MAJOR RECOMMENDATIONS

**ACR Appropriateness Criteria®**

**Clinical Condition: Imaging After Total Knee Arthroplasty**

**Variant 1: Pain after TKA: initial evaluation.**

  ---------------------------------------------------------------------------
  **Radiologic         **Appropriateness   **Comments**
  Procedure**          Rating**            
  -------------------- ------------------- ----------------------------------
  X-ray, knee          9                   Standing views of both legs can be
                                           used to assess the mechanical axis
                                           of both lower extremities.

  X-ray, knee,         1                    
  fluoroscopy                              

  CT, knee             1                    

  MRI, knee            1                    

  NM, bone scan        1                    

  FDG-PET, knee        1                    

  INV, aspiration,     1                    
  knee                                     

  ***Appropriateness                       
  Criteria Scale*\                         
  1 2 3 4 5 6 7 8 9\                       
  1 = Least                                
  appropriate 9 = Most                     
  appropriate**                            
  ---------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 2: Pain after TKA: positive aspiration for infection.**

  ---------------------------------------------------------------------------
  **Radiologic         **Appropriateness   **Comments**
  Procedure**          Rating**            
  -------------------- ------------------- ----------------------------------
  CT, knee             1                    

  MRI, knee            1                    

  NM, bone scan        1                    

  NM, gallium scan     1                    

  NM, bone and         1                    
  indium-111 WBC scan                      

  NM, indium-111 WBC   1                    
  and sulfur colloid                       
  scan                                     

  NM, IgG scan         1                    

  FDG-PET, knee        1                    

  ***Appropriateness                       
  Criteria Scale*\                         
  1 2 3 4 5 6 7 8 9\                       
  1 = Least                                
  appropriate 9 = Most                     
  appropriate**                            
  ---------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 3: Pain after TKA: positive x-ray for loosening. Negative
aspiration for infection.**

  ---------------------------------------------------------------------------
  **Radiologic         **Appropriateness   **Comments**
  Procedure**          Rating**            
  -------------------- ------------------- ----------------------------------
  X-ray, knee,         1                    
  fluoroscopy                              

  CT, knee             1                    

  MRI, knee            1                    

  NM, bone scan        1                    

  FDG-PET, knee        1                    

  X-ray, arthrography, 1                    
  knee                                     

  ***Appropriateness                       
  Criteria Scale*\                         
  1 2 3 4 5 6 7 8 9\                       
  1 = Least                                
  appropriate 9 = Most                     
  appropriate**                            
  ---------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 4: Pain after TKA: negative x-ray for loosening. Negative
aspiration for infection.**

  ---------------------------------------------------------------------------
  **Radiologic         **Appropriateness   **Comments**
  Procedure**          Rating**            
  -------------------- ------------------- ----------------------------------
  CT, knee             7                   For osteolysis or component
                                           malposition.

  NM, bone scan        6                   Reasonable screening test.

  NM, indium-111 WBC   6                   If persistent high clinical
  and sulfur colloid                       suspicion of infection.
  scan                                     

  MRI, knee            5                   Expensive, less experience than
                                           other tests.

  X-ray, knee,         2                    
  fluoroscopy                              

  NM, gallium scan     1                    

  NM, bone and         1                    
  indium-111 WBC scan                      

  NM, IgG scan         1                    

  FDG-PET, knee        1                    

  ***Appropriateness                       
  Criteria Scale*\                         
  1 2 3 4 5 6 7 8 9\                       
  1 = Least                                
  appropriate 9 = Most                     
  appropriate**                            
  ---------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 5: Routine follow-up of asymptomatic patient with TKA.**

  ---------------------------------------------------------------------------
  **Radiologic         **Appropriateness   **Comments**
  Procedure**          Rating**            
  -------------------- ------------------- ----------------------------------
  X-ray, knee,         9                    
  AP/lateral,                              
  standing, and                            
  tangential patellar                      
  views                                    

  X-ray, knee, tunnel  1                    
  views                                    

  X-ray, knee,         1                    
  fluoroscopy                              

  CT, knee             1                    

  MRI, knee            1                    

  ***Appropriateness                       
  Criteria Scale*\                         
  1 2 3 4 5 6 7 8 9\                       
  1 = Least                                
  appropriate 9 = Most                     
  appropriate**                            
  ---------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Summary of Literature Review**

**Routine Imaging**

*Radiography*

The timing of postoperative radiographs has been evaluated in an effort
to decrease costs. Postoperative in-hospital radiographs are thought
unnecessary if the surgery was uncomplicated. Baseline radiographs are
suggested at the first outpatient visit (e.g., at 6 weeks).

The effectiveness of radiographs obtained upon admission to a
rehabilitation facility following hip or knee arthroplasty has been
studied. A retrospective review examined the charts of 209 patients
admitted after total knee replacement and found 2 patients (0.95%) had
abnormal findings on radiographs. There was no change in the length of
hospital stay or the medical intervention required in these patients,
leading the authors to conclude that routine radiography upon admission
to a rehabilitation facility after knee replacement surgery is not cost
effective.

Later follow-up is directed toward identifying any of the complications
discussed below, particularly loosening.

**Complications**

Identification of the cause of a painful total knee arthroplasty (TKA)
is important preoperatively since \"...re-operation is unwise and
frequently associated with suboptimal results\" in cases of unexplained
pain.

**Loosening**

In one series, loosening was a cause of revision in 34% of cases
performed 2 years or more after implant insertion. One group of
researchers defined loosening on radiographs by the presence of
prosthetic fracture, cement fracture, periprosthetic fracture, or gross
component migration. Assessment of radiolucent lines has been an
important tool in defining fixation and therefore, conversely,
loosening. Loosening is suggested when 1) there is progressive widening
of a lucent zone on follow-up examinations, 2) there is greater than a 2
mm wide lucent zone at the cement bone interface or any lucency at the
metal-cement or metal-bone interface, or 3) the lucent zone is
extensive, especially if around the pegs or stem of a component. These
lucent lines should be distinguished from more diffuse bone loss that
occurs in areas of decreased stress (\"stress shielding\").

Fluoroscopy may be useful to see lucent lines in profile that could be
obscured on standard anterior-posterior (AP) radiographs.

Bone scintigraphy may be helpful in diagnosing loosening, especially
when obtained many years after surgery. This delay in maximum utility is
due to the observation that positive bone scans are noted in 20% of
asymptomatic knees a year after surgery and in 12.5% of individuals 2
years postoperatively. Generally, increased isotope uptake on the static
scan but not on the blood pool scans is thought more likely due to
loosening than to infection. Normal scans are most helpful, indicating
that loosening or infection is unlikely. Evaluation of 80 bone scans in
patients with symptomatic TKAs found that the method distinguished
abnormal patients (loosening or infection) from normal ones (sensitivity
of 92.3%) but was unable to distinguish between these two abnormal
conditions. The negative predictive value (NPV) of 95% made a normal
scan reassuring. Serial bone scans may be more helpful than a single
examination.

**Infection**

Infection occurs in 1% to 4% of TKAs and may be acute or delayed. Late
infection has been defined as occurring at least 3 months post surgery.
In one series, infection was responsible for 25.4% of early revisions
and 7.8% of revisions performed more than 2 years after the initial
operation. Early acute infections after TKA are usually clinically
evident by pain, swelling, fever, systemic symptoms, and erythema.
*Staphylococcus epidermidis* and *staphylococcus aureus* are the most
common organisms associated with these infections. Low grade or chronic
infections may be more difficult to identify. One study, for example,
noted that the diagnosis of infection was not obvious in 53% of knees
prior to revision arthroplasty.

*Clinical Features*

Pain is the most common presenting symptom; however, it is a nonspecific
finding. Night pain or pain at rest is typical of infection, whereas
pain on weight bearing is more consistent with mechanical loosening.
Some authors suggest that infection be excluded in all patients with
persistent pain more than 6 months following joint replacement.

Loosening may result from infection. A knee may be infected without the
presence of fever, chills, erythema, or swelling.

*Laboratory*

Laboratory findings are often nonspecific. Peripheral leukocyte counts
are not elevated in most patients with infected prostheses.
Sedimentation rates are abnormal in patients with infection but this
finding may also be seen in uninfected patients, limiting the value of
the test. A retrospective review of 68 patients undergoing hip and knee
revision surgery indicated that C reactive protein (CRP) was
significantly higher in patients with infection compared to those with
loosening (sensitivity 79% for all prostheses), although a normal level
did not exclude infection. A large multicenter study found CRP and joint
aspiration to be the most useful tools to diagnose infection.

*Aspiration*

Knee joint aspiration has been found to be extremely useful in
diagnosing joint infection after TKA. One study found a sensitivity,
specificity, and accuracy of 100% for aspiration in a series of 43 knees
with pain, instability, loosening, or suspected infection undergoing
surgical revision. In contrast, radiographic findings did not separate
infected from noninfected patients. Another study found joint aspiration
to be 100% specific and 75% sensitive for diagnosing infection and to be
the best test for diagnosing infection in a group of total hip and knee
replacement patients. A third study found that early aspiration led to a
significant reduction in the duration of treatment and a better outcome.
In 16% of patients, more than 3 aspirations were necessary to obtain a
positive culture. Another group of researchers noted that in contrast to
aspiration of total hip replacements where false positive results are
more common, aspirations of knee joints are more often falsely negative.
This was thought to most often result from antibiotic treatment. At
least 2 weeks off antibiotics is recommended before the aspiration is
performed (with careful clinical monitoring for sepsis), but as long as
a month may be necessary for cultures of aspirated fluid to become
positive. Therefore, a repeat aspiration should be done weekly if the
first aspiration is negative and clinical suspicion for infection
remains high. Even with a negative preoperative aspiration,
intra-operative tissue may indicate infection. Another group of
researchers, after literature review and a multicenter trial, advocated
CRP and joint aspiration as the best tools for diagnosing prosthetic
joint infection. When CRP level is greater than 10 mg/L, repeat joint
aspiration or biopsy is suggested.

*Radiographs*

One study found radiographs not to be helpful since loosening,
periostitis, focal osteolysis, and radiolucent lines were seen in both
infected and uninfected knees. Most importantly, infection may be
present with a \"normal\" radiographic appearance.

*Bone Scan*

It is usually stated that bone scintigraphy is useful for excluding
infection but of limited value in detecting it. Thus sensitivity is high
and specificity is low.

Increased uptake may persist on bone scan even at 2 years after surgery.
Infection is more likely than aseptic loosening if there is increased
uptake on both blood pool and delayed images. Analysis of 80 bone scans
in patients with postoperative pain found that no patient with infection
had a negative scan. Patients with abnormal scans should be further
assessed.

*White Blood Cell Scan*

White blood cells (WBCs) may be labeled with technetium-99m or
indium-111. Leucocyte scanning using indium-111 was introduced in the
1980s. Labeling leukocytes with indium-111 requires that the patient\'s
venous blood sample be drawn and the WBCs isolated and labeled with
indium-111 oxine. Indium-labeled WBCs are then injected intravenously
prior to scanning. Accurate interpretation requires comparison of the
indium isotope uptake to activity on bone scan; a positive indium scan
for infection generally requiring increased indium-111 uptake either in
a different distribution (an \"incongruent\" scan) or in greater
intensity than on the bone scan. Indium labels both acute and chronic
WBCs, and this may account for positive scans in other conditions in
which inflammatory changes may be present, such as particle disease. A
small sample of indium scans in uncomplicated postoperative TKA patients
also showed that inflammation can persist around the operative site.

One study evaluated patients with loose or painful knee prostheses and
found a sensitivity of 88%, specificity of 78%, positive predictive
value (PPV) 75% and NPV of 90% for infection. The examination was not
recommended as routine because of the expense, complexity and limited
sensitivity, specificity, PPV, and accuracy. In equivocal cases, and
when an experienced musculoskeletal pathologist is not available to
interpret an intra-operative frozen section, these authors noted that a
negative indium scan may be helpful to suggest the absence of infection.

Evaluation of indium scanning may lead to a high false positive rate
that is thought to be due to marrow packing. The addition of
technetium-99m-labeled sulfur colloid scanning has been investigated to
reduce this. One study, however, found that low sensitivity and the
potential for false negative results made this combination of scans of
limited utility for diagnosing prosthetic infection, and therefore it is
no longer used in their institution. In that group of 22 total knee
prostheses evaluated and later operated upon, there was a sensitivity of
66%, specificity of 100%, PPV of 100%, NPV of 88%, and accuracy of 91%.
The addition of blood pool and flow scans was investigated to determine
if hyperemia led to a match of bone indium uptake (and therefore, a
falsely negative scan). These additional scans decreased the number of
false negative findings (sensitivity of 83%, specificity of 94%, PPV of
83%, NPV of 94%). Overall, however, the performance of the
indium/colloid scan protocol was again thought to be of limited clinical
utility. Semiquantitative assessment of WBC scans has, however, produced
\> 90% sensitivity and specificity in one series. In another study, it
was noted that positive indium WBC scan and sedimentation rates were the
most predictive variables for detecting septic prostheses.

A study of a small series of total knee arthroplasties using indium-111
IgG found the sensitivity of this agent for infection to be high but its
specificity low (sensitivity 100%, specificity 50%). In a multicenter
trial of various methods for diagnosing hip and knee infections, scans
using tagged white cells or radiolabelled immunoglobulin demonstrated a
sensitivity of 74% and specificity of 76% for diagnosing infection.
Literature review indicates sensitivities of 38% to 100% and
specificities 41% to 100% for WBC scans of joint prostheses. These
studies were, therefore, not recommended as routine for differentiating
mechanical failure from occult infection in painful loose total knee
prostheses.

*FDG-PET*

One study cites reports indicating that elevated glycolytic activity
causes inflammatory cells such as neutrophils and activated macrophages
to be fluorodeoxyglucose (FDG) avid at sites of inflammation and
infection. Thus, fluorodeoxyglucose-positron emission tomography
(FDG-PET) imaging may be useful for detecting infection after joint
replacement. The examination is much faster (a few hours) and less
expensive than combined bone, marrow, and indium scintigraphy. In one
series, the use of FDG-PET scanning combined with bone scanning showed
no advantage over hexamethylpropyleneamine oxime (HMPAO)-labeled WBC
scan and bone scanning. Another study of 36 painful knee prostheses
examined using 18F-FDG-PET scanning showed identification of 10 of 11
infected cases but false positive results in 7 cases (sensitivity of
90.9%, specificity of 72%, and accuracy of 77.8% for detecting
infection). This was lower accuracy than for assessment of hip
prostheses. The cause for the high number of false positives was not
known. Another group of researchers found diffuse synovial and focal
extrasynovial FDG-PET uptake in patients with component malrotation.
They concluded that this test is noncontributory in individual patients
with persistent pain.

**Wear**

*Polyethylene thickness*. The polyethylene articular surface of a total
knee prosthesis may undergo true wear, deformation, and creep that lead
to a decrease in the thickness of the polyethylene; these may be
clinically referred to as \"wear.\" Several methods have been used to
study the thickness of the polyethylene and thus the extent of wear.

One study examined single leg standing frontal radiographs of the knees
for assessing of polyethylene thickness. Two types of measurement were
made: 1) minimum distance from the metallic femoral condyle to the metal
backing baseplate, and 2) minimum distance from the metallic femoral
condyle to a line through the top surface of the baseplate at its widest
dimension. The latter method proved more accurate and less affected by
tilting of the tibial component. Overall, 87% of measurements using the
second method were within 1 mm of the known implant thickness (accuracy
roughly +/- 1 mm initially). However, accuracy decreased for evaluating
polyethylene thickness in patients with wear requiring revision.

Because of the tilt of the tibial component in some cases, fluoroscopy
has been used to align radiographs perpendicular to the joint surface.
This allows measurement of the thickness of the polyethylene liner so
that decreases in liner thickness (indicating wear) can be measured.
Correction for magnification is made using the known diameter of a
portion of the tibial component. In vivo assessment has shown
repeatability (precision) of these measurements to be 0.2 mm with a 99%
confidence level. The major source of variation is angulation of the
tube in the craniocaudal direction; a 0.33 mm (6.5%) change in mean
insert thickness is seen per degree of angulation. Another researcher
noted that the magnification error cannot be reduced to ≤1 mm using
fluoroscopy.

Varus/valgus stress has been added to the fluoroscopic examination to
improve evaluation of polyethylene thickness. The coefficient of
variation for repeat examination was 3.4%.

*Granulomas*. Oblique posterior femoral condylar radiographs have been
recommended for evaluating the posterior condyles after TKA. This method
was thought to be especially helpful when a posterior stabilized
prosthesis is in place.

Sonography is under investigation for evaluating the thickness of
polyethylene liners but is not in general use.

Focal osteolysis due to wear particles may be visible on radiographs,
and routine surveillance has been suggested even in asymptomatic
patients for this assessment. In one study, focal osteolysis was defined
as an isolated area of lucency measuring at least 3 mm in diameter. It
may be difficult to differentiate these lytic defects from stress
shielding (osteoporosis).

*Computed Tomography*

One study recommends using computed tomography (CT) examination in
patients with painful knee prostheses and equivocal radiographs,
particularly for:

1.  Loosening: to show the extent and width of lucent zones that may be
    less apparent on radiographs.

2.  Osteolysis: CT is superior to radiographs for this diagnosis. These
    authors recommend CT be obtained in patients with painful knee
    prostheses with normal or equivocal radiographs and increased uptake
    on all three phases of a bone scan to look for osteolysis.

3.  Assessing rotational alignment of the femoral component.

4.  Detecting subtle or occult periprosthetic fractures.

Arthrography CT may be useful in documenting large displaced
polyethylene fragments. In one case, arthrography CT allowed
identification of the nonopaque polyethylene fragment of the tip of a
posterior stabilized prosthesis.

*Magnetic Resonance Imaging*

Improved pulse sequences and techniques have facilitated the evaluation
of the periprosthetic soft tissues and bone, allowing demonstration of
focal osteolysis and inflammatory synovitis, as well as ligament and
tendon abnormalities.

**Patellar Complications**

Patellar complications include subluxation, dislocation, fracture,
component loosening or wear, impingement, and osteonecrosis. Radiographs
are usually satisfactory for diagnosing patellar complications.
Malposition of femoral and tibial components may affect patellar
alignment. The rotation of tibial and femoral components may be
evaluated on CT examination using anatomical landmarks. MRI may also
allow this evaluation.

Patellar fractures occur in up to 3.8% of patients, usually within the
first few postoperative years. Most are not associated with prior
injury, and many are asymptomatic, highlighting the importance of
radiography for their identification. Risk factors include older age,
osteonecrosis, lateral release, surgical technique, incorrect prosthetic
alignment (femorotibial or patellofemoral), and improper patellar
resection. Transverse fractures are thought to be associated with
patellar maltracking, while vertical fractures often occur through a
fixation hole.

**Abbreviations**

-   AP, anteroposterior

-   CT, computed tomography

-   FDG-PET, fluorodeoxyglucose positron emission tomography

-   IgG, immunoglobulin G

-   INV, invasive

-   MRI, magnetic resonance imaging

-   NM, nuclear medicine

-   TKA, total knee arthroplasty

-   WBC, white blood cell

#### CLINICAL ALGORITHM(S)

Algorithms were not developed from criteria guidelines.

### EVIDENCE SUPPORTING THE RECOMMENDATIONS

#### TYPE OF EVIDENCE SUPPORTING THE RECOMMENDATIONS

The recommendations are based on analysis of the current literature and
expert panel consensus.

### BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS

#### POTENTIAL BENEFITS

Selection of appropriate radiologic imaging procedures for evaluation of
patients after total knee arthroplasty

#### POTENTIAL HARMS

-   Aspirations of knee joints are often falsely negative.

-   Indium scanning and fluorodeoxyglucose positron emission tomography
    (FDG-PET) can render false positive results

### QUALIFYING STATEMENTS

#### QUALIFYING STATEMENTS

An American College of Radiology (ACR) Committee on Appropriateness
Criteria and its expert panels have developed criteria for determining
appropriate imaging examinations for diagnosis and treatment of
specified medical condition(s). These criteria are intended to guide
radiologists, radiation oncologists, and referring physicians in making
decisions regarding radiologic imaging and treatment. Generally, the
complexity and severity of a patient\'s clinical condition should
dictate the selection of appropriate imaging procedures or treatments.
Only those exams generally used for evaluation of the patient\'s
condition are ranked. Other imaging studies necessary to evaluate other
co-existent diseases or other medical consequences of this condition are
not considered in this document. The availability of equipment or
personnel may influence the selection of appropriate imaging procedures
or treatments. Imaging techniques classified as investigational by the
U.S. Food and Drug Administration (FDA) have not been considered in
developing these criteria; however, study of new equipment and
applications should be encouraged. The ultimate decision regarding the
appropriateness of any specific radiologic examination or treatment must
be made by the referring physician and radiologist in light of all the
circumstances presented in an individual examination.

### IMPLEMENTATION OF THE GUIDELINE

#### DESCRIPTION OF IMPLEMENTATION STRATEGY

An implementation strategy was not provided.

#### IMPLEMENTATION TOOLS

Personal Digital Assistant (PDA) Downloads

For information about
[availability](#identifying-information-and-availability), see the
\"Availability of Companion Documents\" and \"Patient Resources\" fields
below.

### INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT CATEGORIES

#### IOM CARE NEED

Getting Better\
Living with Illness

#### IOM DOMAIN

Effectiveness

### IDENTIFYING INFORMATION AND AVAILABILITY

#### BIBLIOGRAPHIC SOURCE(S)

Weissman BN, Dalinka MK, Daffner RH, Jacobson JA, Morrison WB, Palmer
WE, Resnik CS, Rubin DA, Schneider R, Schweitzer ME, Seeger LL,
Steinbach LS, Haralson RH III, Expert Panel on Musculoskeletal Imaging.
Imaging after total knee arthroplasty. \[online publication\]. Reston
(VA): American College of Radiology (ACR); 2006. 7 p. \[45 references\]

#### ADAPTATION

Not applicable: The guideline was not adapted from another source.

#### DATE RELEASED

2006

#### GUIDELINE DEVELOPER(S)

American College of Radiology - Medical Specialty Society

#### SOURCE(S) OF FUNDING

The American College of Radiology (ACR) provided the funding and the
resources for these ACR Appropriateness Criteria®.

#### GUIDELINE COMMITTEE

Committee on Appropriateness Criteria, Expert Panel on Musculoskeletal
Imaging

#### COMPOSITION OF GROUP THAT AUTHORED THE GUIDELINE

*Panel Members*: Barbara N. Weissman, MD; Murray K. Dalinka, MD; Richard
H. Daffner, MD; Jon A. Jacobson, MD; William B. Morrison, MD; William E.
Palmer, MD; Charles S. Resnik, MD; David A. Rubin, MD; Robert Schneider,
MD; Mark E. Schweitzer, MD; Leanne L. Seeger, MD; Lynne S. Steinbach,
MD; Robert H. Haralson III, MD

#### FINANCIAL DISCLOSURES/CONFLICTS OF INTEREST

Not stated

#### GUIDELINE STATUS

This is the current release of the guideline.

The appropriateness criteria are reviewed annually and updated by the
panels as needed, depending on introduction of new and highly
significant scientific evidence.

#### GUIDELINE AVAILABILITY

Electronic copies: Available in Portable Document Format (PDF) from the
[American College of Radiology (ACR) Web
site](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/pdf/ExpertPanelonMusculoskeletalImaging/ImagingafterTotalKneeArthroplastyDoc13.aspx).

ACR Appropriateness Criteria® *Anytime*, *Anywhere*™ (PDA application).
Available from the [ACR Web
site](http://www.acr.org/SecondaryMainMenuCategories/ACRStore/FeaturedCategories/QualityandSafety/ac_pda.aspx).

Print copies: Available from the American College of Radiology, 1891
Preston White Drive, Reston, VA 20191. Telephone: (703) 648-8900.

#### AVAILABILITY OF COMPANION DOCUMENTS

The following is available:

-   ACR Appropriateness Criteria®. Background and development. Reston
    (VA): American College of Radiology; 2 p. Electronic copies:
    Available in Portable Document Format (PDF) from the [American
    College of Radiology (ACR) Web
    site](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/pdf/background_dev.aspx).

#### PATIENT RESOURCES

None available

#### NGC STATUS

This NGC summary was completed by ECRI Institute on April 25, 2007.

#### COPYRIGHT STATEMENT

Instructions for downloading, use, and reproduction of the American
College of Radiology (ACR) Appropriateness Criteria® may be found on the
[ACR Web
site.](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/ACRAppropriatenessCriteriaTermsandConditionsDoc1.aspx)

### DISCLAIMER

#### NGC DISCLAIMER

The National Guideline Clearinghouse™ (NGC) does not develop, produce,
approve, or endorse the guidelines represented on this site.

All guidelines summarized by NGC and hosted on our site are produced
under the auspices of medical specialty societies, relevant professional
associations, public or private organizations, other government
agencies, health care organizations or plans, and similar entities.

Guidelines represented on the NGC Web site are submitted by guideline
developers, and are screened solely to determine that they meet the NGC
Inclusion Criteria which may be found at
<http://www.guideline.gov/about/inclusion.aspx> .

NGC, AHRQ, and its contractor ECRI Institute make no warranties
concerning the content or clinical efficacy or effectiveness of the
clinical practice guidelines and related materials represented on this
site. Moreover, the views and opinions of developers or authors of
guidelines represented on this site do not necessarily state or reflect
those of NGC, AHRQ, or its contractor ECRI Institute, and inclusion or
hosting of guidelines in NGC may not be used for advertising or
commercial endorsement purposes.

Readers with questions regarding guideline content are directed to
contact the guideline developer.

Bottom of Form

© 1998-2008 National Guideline Clearinghouse

Date Modified: 11/3/2008