In this section are going to learn how to detect subtle tibial plateau fractures. Tibial plateau fractures have important clinical implications and can be commonly missed if you don’t recognize the important sign used to detect these fractures.
Take this frontal view of the knee:
As you can see there is no sign of an obvious fracture.
Now look at this oblique view:
Again, there is no obvious sign of a fracture.
Now let’s look at the 3rd and last view, the lateral view
Again, there is no obvious fracture. But you can now see a large knee effusion (fluid in the joint). More importantly, you see 2 different density levels clearly separated and delineated by the arrows shown below.
So what we have is called lipohemearthrosis of the knee joint which is essentially synonymous for a tibial plateau fracture. The concept of lipohemearthrosis is a very important one.
First let’s look at the meaning.
So that means you have fat and blood in the knee joint. Let’s look at how that happens.
When you have a fracture of the tibial plateau, the bone marrow, which is composed of blood and fat, actually escapes from the fractured cortex and shoots up into the knee joint. The knee effusion is composed of blood and fat, hence lipohemearthrosis.
The red arrow is an example of the bone marrow shooting up to the knee joint once the cortex of the bone has been breached and fractured.
The fat and blood, because of their different densities, will separate and layer, especially in an injured immobile patient. So by the time the X-ray is done in the urgent care or the emergency room, the two layers will have likely separated and can be delineated. Once you see lipohemearthrosis, you have to strongly suspect a tibial plateau fracture and even if you do not an obvious fracture on the X-ray.
At this point, you have to take the next step and order a CT scan or MRI to detect the fracture. Usually a CT scan is performed since it is faster and more available in the emergency setting.
The knee effusion is composed of 2 separate densities made of blood and fat.
So the next Step is to a CT scan. Please watch my video as it will take you through multiple fractures of the tibial plateau displayed on CT that could not be identified by these X-Rays.
So, in conclusion, the only sign that helped us have a high index of suspicion for a radiographically occult fracture was the finding of lipohemearthrosis. Next time you encounter a large effusion in a patient with history trauma, make sure to look for this sign. If your index of suspicion is high, you can either get an additional cross table lateral X-Ray view of the knee to help see the fat-fluid level or just recommend a CT scan.
CT scan image showing one of the fracture sites. Please refer to the video to see all of the fractures.
Posted on behalf of Advanced Healing Institute
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