Fat pad separation sign (knee joint effusion)

Last revised by Mostafa Elfeky on 9 May 2023

Citation, DOI, disclosures and article data

Citation:

Elfeky M, Fat pad separation sign (knee joint effusion). Reference article, Radiopaedia.org (Accessed on 18 Apr 2024) https://doi.org/10.53347/rID-168031

DOI:

https://doi.org/10.53347/rID-168031

Permalink:

https://radiopaedia.org/articles/168031?iframe=true

rID:

168031

Article created:

7 May 2023, Mostafa Elfeky ◉

Disclosures:

At the time the article was created Mostafa Elfeky had no financial relationships to ineligible companies to disclose.

View Mostafa Elfeky's current disclosures

Last revised:

9 May 2023, Mostafa Elfeky ◉

Disclosures:

At the time the article was last revised Mostafa Elfeky had no financial relationships to ineligible companies to disclose.

View Mostafa Elfeky's current disclosures

Revisions:

1 time, by 1 contributor - see full revision history and disclosures

Fat pad separation sign refers to the separation of the anterior suprapatellar and posterior suprapatellar (prefemoral) fat pads on lateral knee radiograph. This sign is useful in diagnosis of knee joint effusion on cross-table (horizontal beam) lateral knee radiographs with more sensitivity than standard knee lateral radiographs ^1,2. Knee joint fluid can be detected as small as 2 mL with diagnostic accuracy near 90% ^1,2.

This sign represents distension of suprapatellar bursa with fluid which is the first site to be filled with fluid in knee joint effusion.

References

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