The Comprehensive Description of Stress Fractures: A New Classification System.
Kaeding CC., Miller T. J Bone Joint Surg Am. 2013. Jul 3;95(13): 1214-20.
Take Home Message: A newly proposed stress fracture classification system grades fractures on a 1-5 scale for a simple, clinically relevant tool that can help foster communication among clinicians and patients.
A stress fracture is typically caused by chronic, repetitive low levels of stress, which eventually overwhelms the bone’s ability to repair itself. The current classification systems for stress fractures vary, depend on a particular imaging modality, and have been poorly integrated into clinical practice. This can lead to confusion between patients and practitioners. Therefore, Kaeding and Miller proposed and tested a new grading system based on clinical and radiographic data to grade stress fractures on a 1-5 scale based on imaging and clinical history:
Grade 1 – asymptomatic stress reaction on imaging (incidental finding)
Grade 2 – pain on exam/ history and evidence of bone fatigue on imaging, but no clear fracture line
Grade 3 – non-displaced fracture line on imaging
Grade 4 – displaced fracture (> 2mm) on imaging
Grade 5 – nonunion on imaging
The researchers specifically tested this classification system for intra-observer and inter-observer reliability using 15 sports medicine physicians. They first explained the grading system to the physicians and then tested them with 20 sample cases at two different times separated by a span of 14 to 21 days. The researcher found good agreement (85.7%) for intra-observer reliability (i.e. most physicians gave the case the same grade when tested on separate occasions), and a good agreement (81%) for interobserver reliability (i.e. most physicians assigned the same grade fracture to any particular case). Finally, the physicians were accurate with the classification system (97.3% accuracy; i.e. most answers were the correct answers as compared with the answer key).
The benefit of this simple classification system, as opposed to previous systems, is that it is reproducible, generalizable, easily applied, and clinically relevant. The researchers behind this study came up with a fracture grading system that could be easily and effectively applied clinically to help manage patients. In addition to fracture grade, location of the fracture is very important in determining prognosis. There are several areas in the body which are prone to non-healing fractures due to limited or tenuous blood supply. The authors suggest that fracture location and grade together can predict prognosis for patients with a stress fracture; but, this may require future research to verify. The benefit of this classification system is that it has been tested specifically for reproducibility and accuracy – making it a potentially useful tool for everyone to use. This classification system may also be generalizable because a clinician could use any imaging modality, thereby allowing the classification system to be used at any location throughout the body and by clinicians who may not have access to advanced imaging. An effective classification system can help foster communication among providers and can also help predict return to activities. For example, a grade 1 fracture may not require any treatment other than monitoring. A grade 2 fracture may require a short period of rest; however, a grade 2 fracture in a high-risk area would be treated more conservatively. A grade 3 fracture would likely require a more extended period of rest whereas a grade 4 or 5 fracture might require surgical intervention. Clarifying the severity of the fracture based on location and grade helps facilitate better communication. It can also eliminate confusing terms such as “stress response” versus “stress fracture”.
Questions for Discussion: Do you think stress fractures need a classification system? Does this system help to clarify the differences between injuries?
Written By: Hallie Labrador MD, MS
Reviewed by: Jeffrey Driban
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Kaeding CC, & Miller T (2013). The comprehensive description of stress fractures: a new classification system. The Journal of Bone and Joint Surgery. American Volume, 95 (13), 1214-20 PMID: 23824390