Though there are many proposed classifications, a gold standard classification system for bone stress injuries hasn’t been determined yet. We don’t have one specific system that factors in both radiographic & clinical characteristics of the injury, can be applied to all fracture sites, and is easily accessible, safe and widely applicable. 

 

With that said, the Fredericson classification system & Arendt classification systems are the most commonly used, so we’ll go into a little more detail on each of them. 

 

The Fredericson system was initially created to classify medial tibial bone stress injuries and grades are as follows, as seen on MRI:

• Grade1: periosteal edema with no bone marrow abnormalities

• Grade 2: periosteal edema, mild bone marrow edema only on T2-weighted images

• Grade 3: periosteal edema, extensive bone marrow edema on both T1 & T2-weighted images

• Grade 4: 

  • A: all of the above + multiple focal areas of intracortical signal changes

  • B: all of the above + linear region of intracortical signal change e.g. fracture line

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Here's an easier-to-comprehend graphic of BSI grading based on the Fredericson classification:

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The Arendt grading system was created using various sites of bone injury and modified the Fredericson with the addition of STIR (short tau inversion recovery) which suppresses the signal from fat tissue. Their grades are:

• Grade1: bone marrow signal change on STIR

• Grade 2: bone marrow signal change on STIR and T2-weighted images

• Grade 3: bone marrow signal change on STIR, T2-weighted images and T1-weighted images with no definite fracture line

• Grade 4: all of the above + visible fracture line on T1 or T2-weighted images

 

As you can see, the presence or absence or periosteal edema does not change the grading in the Arendt system which differs from the Fredericson. 

 

It is possible though rare for a stress fracture to progress to a complete fracture if left untreated, particularly at high-risk sites like the femoral neck - this is why it’s important to catch these early, to both prevent more serious injury from happening and to facilitate faster recovery timelines. 

 

All bone stress injuries are not created equal. They exist on a pretty broad spectrum - which is one reason why pain presentation and recovery can vary so significantly from one individual or injury to the next. 

 

Your recovery should be individualized based not only on your specific grade & site of injury, but also your injury history, current health status and future goals. 

 

If you’re concerned about recurrent bone stress injuries or looking for help rehabbing from one, let’s chat! Click the button below to reach out.