CITW: Case 2

Two cases this week! Thank you to Dr. David Kaplan for submitting the first case, while the second case was one seen by myself and Dr. Paul Cheung.

Case 1:

58 y/o male sustained blunt force trauma to the lateral aspect of his right knee. On exam, there is a mild right knee effusion, but no obvious deformities. Pain with ROM. Neurovascularly intact. No ligamentous laxity appreciated. X-rays of the right knee are obtained:

Kap Knee

Case 2:

22 y/o male sustained a gunshot wound to the right knee. On exam, there is an entrance wound on the posterior-lateral aspect of the knee, but no exit wound. There is pain with ROM of the knee and a mild effusion is appreciated. No obvious deformities. Neurovasculary intact. No ligamentous laxity appreciated. Initial plain films demonstrate the bullet lodged in the mid-thigh. Physical exam findings and x-rays of the right knee:

Knee

TR Knee

Given concern for an open joint, an aspiration is performed prior to irrigation, and the following aspirate is obtained:

LHA1

What’s the diagnosis?

Lipohemarthrosis

In the previous image, note the fat globules floating within the bloody aspirate. On the lateral knee x-ray you can see an effusion where the blood and fat are layering out. This finding is highly suspicious for an intracapsular fracture, which may or may not be demonstrable on plain films.

TR Knee Dict(Also note the aforementioned bullet…)

CT correlation is recommended:
Case 1: Lateral tibial plateau fracture (not seen on plain films)

Kap CT

Case 2: Lateral femoral condyle ballistic injury (not seen on plain films)

TR CT

Case conclusions:

Case 1: Orthopedics evaluated the patient, and he was discharged home in a knee immobilizer, crutches, and orthopedics follow up.

Case 2: Patient’s knee was washed out with 1 liter of NS and then wrapped. He was discharged home on antibiotics and PCP follow up.

Note the information in these cases has been purposefully altered to protect the identity of the patients. The patient’s consented to the use of these images.

4 thoughts on “CITW: Case 2

  1. Nice pickup on that layering in Case 2’s X-ray. I’m sure I would have glossed right over that. (In fact, I did!) Great cases, thank you!

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