A 26 y.o. woman comes to the ED with elbow pain

She believes she may have been run over by a car on the evening pta but she and the driver of the Uber she was in have no recollection of the event other than that they were intoxicated.

What do you notice?

Our patient had severe elbow pain after a trauma and a subtle radial neck fracture. If there is suspicion for a subtle fracture, look for displacement of the fat pads. Fluid  in the elbow joint is not usually seen because it is the same density as the surrounding muscle but the fat pads can be displaced and seen on plain film as in out patient.

The “sail sign” refers to the triangular appearance of the displaced anterior fat pad  in the elbow and is an indication of an occult fracture.  In adults this is most commonly a radial head fracture, while in children a supracondylar fracture is more likely.

While the elbow can present with an effusion after trauma,  other joints can present with effusions as well.   A lipohemarthrosis, where marrow  and blood spill into the joint capsule can be seen on plain xray in tibial plateau fractures.  A lipohemarthrosis has also been described on hip, shoulder and wrist fractures.

lipohemarthrosis with a tibial plateau fracture.

Our patient had a CT scan showing an impacted radial neck fracture with joint effusion. Ortho prescribed a sling and early range of motion exercises since it was not displaced. 

Daniels C, Gliedt J, Enix D. Radial neck fracture presenting to a chiropractic clinic: a case report and literature reviewe. Chiropr Man therap  chiropractic & manual therapies 22 :14(2014)

Occult injury of the elbow and joint effusion-everything you need to know-Nabil Ebraheim  https://www.youtube.com/watch?v=JMjWsXYC8kU

. Thawait S, Vossen J, Muro G, Karol I. MRI Illustration of Traumatic Lipohemarthrosis of the Wrist Joint Due to a Scaphoid Fracture. Radiol Case Rep. 2012;7(3):688. doi:10.2484/rcr.v7i3.688 - Pubmed

https://dontforgetthebubbles.com/elbow-xr-interpretation/ great review of pediatric elbow injuries