The Comprehensive Description of
Stress Fractures: A New Classification System.

CC., Miller T. J Bone Joint Surg Am. 2013. Jul 3;95(13): 1214-20.

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:
1 – asymptomatic stress reaction on imaging (incidental finding)
2 – pain on exam/ history and evidence of bone fatigue on imaging, but no clear
fracture line
3 – non-displaced fracture line on imaging
4 – displaced fracture (> 2mm) on imaging
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”. 

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