American College of Radiology
ACR Appropriateness Criteria®

Acute Trauma to the Knee

Variant 1: Adult or child >1 year old. Fall or twisting injury, no focal tenderness, no effusion; able to walk. First study.
Procedure Appropriateness Category SOE Adult RRL Peds RRL Rating Median Final Tabulations
1 2 3 4 5 6 7 8 9
MRI knee without IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 2 n/a 0 0 0 0 0 0 0 0 0
X-ray knee Usually not appropriate ☢ <0.1 mSv ☢ <0.03 mSv [ped] 2 n/a 0 0 0 0 0 0 0 0 0
CT knee without IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
CT knee without and with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
CT knee with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRA knee without IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRA knee without and with IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRI knee without and with IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
Tc-99m bone scan with SPECT lower extremity Usually not appropriate ☢☢☢ 1-10 mSv 1 n/a 0 0 0 0 0 0 0 0 0
US knee Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
Variant 2: Adult or child >1 year old. Fall or twisting injury, with one or more of the following: focal tenderness, effusion, inability to bear weight. First study.
Procedure Appropriateness Category SOE Adult RRL Peds RRL Rating Median Final Tabulations
1 2 3 4 5 6 7 8 9
X-ray knee Usually appropriate ☢ <0.1 mSv ☢ <0.03 mSv [ped] 9 n/a 0 0 0 0 0 0 0 0 0
MRI knee without IV contrast May be appropriate O 0 mSv O 0 mSv [ped] 5 n/a 0 0 0 0 0 0 0 0 0
CT knee without IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 2 n/a 0 0 0 0 0 0 0 0 0
Tc-99m bone scan with SPECT lower extremity Usually not appropriate ☢☢☢ 1-10 mSv 2 n/a 0 0 0 0 0 0 0 0 0
US knee Usually not appropriate O 0 mSv O 0 mSv [ped] 2 n/a 0 0 0 0 0 0 0 0 0
CT knee without and with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRA knee without IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
CT knee with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRA knee without and with IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRI knee without and with IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
Variant 3: Adult or child >1 year old. Fall or twisting injury with either no fracture or a Segond fracture seen on a radiograph, suspect internal derangement. Next study.
Procedure Appropriateness Category SOE Adult RRL Peds RRL Rating Median Final Tabulations
1 2 3 4 5 6 7 8 9
MRI knee without IV contrast Usually appropriate O 0 mSv O 0 mSv [ped] 9 n/a 0 0 0 0 0 0 0 0 0
CT knee without IV contrast May be appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 5 n/a 0 0 0 0 0 0 0 0 0
CT knee with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
CT knee without and with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRA knee without IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRA knee without and with IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRI knee without and with IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
Tc-99m bone scan with SPECT lower extremity Usually not appropriate ☢☢☢ 1-10 mSv 1 n/a 0 0 0 0 0 0 0 0 0
US knee Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
Variant 4: Adult or child >1 year old. Fall or twisting injury with a tibial plateau fracture on a radiograph, with additional bone or soft-tissue injury suspected. Next study.
Procedure Appropriateness Category SOE Adult RRL Peds RRL Rating Median Final Tabulations
1 2 3 4 5 6 7 8 9
CT knee without IV contrast Usually appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 9 n/a 0 0 0 0 0 0 0 0 0
MRI knee without IV contrast Usually appropriate O 0 mSv O 0 mSv [ped] 7 n/a 0 0 0 0 0 0 0 0 0
CT knee with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
CT knee without and with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRA knee without IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRA knee without and with IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRI knee without and with IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
Tc-99m bone scan with SPECT lower extremity Usually not appropriate ☢☢☢ 1-10 mSv 1 n/a 0 0 0 0 0 0 0 0 0
US knee Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
Variant 5: Adult or child >1 year old. Injury to knee, mechanism unknown. Focal patellar tenderness, effusion, able to walk.
Procedure Appropriateness Category SOE Adult RRL Peds RRL Rating Median Final Tabulations
1 2 3 4 5 6 7 8 9
X-ray knee Usually appropriate ☢ <0.1 mSv ☢ <0.03 mSv [ped] 9 n/a 0 0 0 0 0 0 0 0 0
MRI knee without IV contrast May be appropriate O 0 mSv O 0 mSv [ped] 5 n/a 0 0 0 0 0 0 0 0 0
CT knee without IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 2 n/a 0 0 0 0 0 0 0 0 0
Tc-99m bone scan with SPECT lower extremity Usually not appropriate ☢☢☢ 1-10 mSv 2 n/a 0 0 0 0 0 0 0 0 0
US knee Usually not appropriate O 0 mSv O 0 mSv [ped] 2 n/a 0 0 0 0 0 0 0 0 0
CT knee without and with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRA knee without IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRA knee without and with IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
CT knee with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRI knee without and with IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
Variant 6: Adult or child >1 year old. Significant trauma to the knee from motor vehicle accident, suspect knee dislocation.
Procedure Appropriateness Category SOE Adult RRL Peds RRL Rating Median Final Tabulations
1 2 3 4 5 6 7 8 9
MRI knee without IV contrast Usually appropriate O 0 mSv O 0 mSv [ped] 9 n/a 0 0 0 0 0 0 0 0 0
X-ray knee Usually appropriate ☢ <0.1 mSv ☢ <0.03 mSv [ped] 9 n/a 0 0 0 0 0 0 0 0 0
CTA lower extremity with IV contrast Usually appropriate ☢☢☢ 1-10 mSv ☢☢☢☢ 3-10 mSv [ped] 7 n/a 0 0 0 0 0 0 0 0 0
Arteriography lower extremity Usually appropriate ☢☢ 0.1-1mSv ☢☢☢ 0.3-3 mSv [ped] 7 n/a 0 0 0 0 0 0 0 0 0
MRA knee without and with IV contrast Usually appropriate O 0 mSv O 0 mSv [ped] 7 n/a 0 0 0 0 0 0 0 0 0
MRA knee without IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 3 n/a 0 0 0 0 0 0 0 0 0
CT knee without IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 2 n/a 0 0 0 0 0 0 0 0 0
Tc-99m bone scan with SPECT lower extremity Usually not appropriate ☢☢☢ 1-10 mSv 2 n/a 0 0 0 0 0 0 0 0 0
US knee Usually not appropriate O 0 mSv O 0 mSv [ped] 2 n/a 0 0 0 0 0 0 0 0 0
CT knee without and with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
CT knee with IV contrast Usually not appropriate ☢ <0.1 mSv ☢☢ 0.03-0.3 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
MRI knee without and with IV contrast Usually not appropriate O 0 mSv O 0 mSv [ped] 1 n/a 0 0 0 0 0 0 0 0 0
Appendix Key

A more complete discussion of the items presented below can be found by accessing the supporting documents at the designated hyperlinks.

Appropriateness Category:The panel’s recommendation for a procedure based on the assessment of the risks and benefits of performing the procedure for the specified clinical scenario.

SOE: Strength of Evidence. The assessment of the amount and quality of evidence found in the peer reviewed medical literature for an appropriateness recommendation.

  • References: The citation number and PMID for the reference(s) associated with the recommendation.
  • Study Quality: The assessment of the quality of an individual reference based on the number of study quality elements described in the reference.

RRL: Relative Radiation Level. A population based assessment of the amount of radiation a typical patient may be exposed to during the specified procedure.

Rating: The final rating (1-9 scale) for the procedure as determined by the panel during rating rounds.

Median: The median rating (1-9 scale) for the procedure as determined by the panel during rating rounds.

Final tabulations: A histogram showing the number of panel members who rated the procedure as noted in the column heading (ie, 1, 2, 3, etc.).

Additional supporting documents about the AC methodology and processes can be found at www.acr.org/ac.