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Three Part Question

In [patient with lower limb stress fractures] what is the [sensitivity and specificity of X-
ray] compared to [gold standard MRI for diagnosis]

Clinical Scenario

A patient presents with a lower limb stress fracture and you wonder what the best first initial investigations should be. You arrange an X-ray of the lower limb, but wonder what the sensitivity and specificity of this investigation is.

Search Strategy

Ovid MEDLINE(R) 1946 to July Week 1 2015
(exp Fractures, stress/ OR insufficiency fracture.mp./OR fatigue fracture.mp./ OR stress injury.mp.) AND (exp X-Ray/ OR plain film radiograph.mp./ OR x-ray.mp.) AND (exp sensitivity and specificity) Limit (English language AND humans AND all adults (<18-64 years))

Search Outcome

17 hits
5 relevancies

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Fayad 2005 USA	59 patients: 30 biopsy proven pathologic fractures and 29 stress fractures	Retrospective cohort study to define CT and MRI features that distinguish pathologic fractures from stress fracture and compare CT and MRI with radiography	Sensitivity	Not given	Poor study design, no control, only 2 researchers involved. All x-rays had some feature in them therefore reviewers were primed to look for something. Not large enough study. Does not explain order of images presented. Overall poor study
			Specificity	Not given
			CT vs X-ray	Radiography better than CT (94-88%) at distinguishing between pathological and stress fractures
Gaeta 2005 Italy	42 patients: 16 female and 26 male All athletic, participated in sport	Cohort study to compare CT, MRI and bone scintigraphy in athletes with clinically suspected early stress injury of tibia	MRI vs CT sensitivity	88%: 42%	Did not compare against control group Used all modalities on all patients
			MRI vs CT specificity	100%: 100%
Boniotti 2002 Italy	50 patients with bone micro injuries	Retrospective cohort study to identify the role of MRI in identifiying bone micro-injuries	X-ray sensitivity	43.6%	Aim not clear Small sample size No control
			X-ray specificity	100%
Feydy 1998 France	15 confirmed diagnosis of LSFT: 9 men and 6 women	Retrospective cohort study to compare the performance of CT and MRI in diagnosis of longitudinal stress fracture of the tibia	X-ray sensitivity	6.5%	Poor study design, no control. All patients had all images done Only two radiologists assessed images Not clear aim to the study No clear parameters set
			X-ray specificity	100%
			Other key findings	MRI is the most sensitive and specific image 73% and 100% respectively
Kasten 2005 Germany	35 patients with average age of 12	Cohort study to describe clinical and radiological findings in adolescent patients with stress fracture	X-ray sensitivity	70%	Abstract only Used adolescents not adults Method unclear No follow up
			X-ray specificity	100%

Comment(s)

4 studies related to the question asked. 2 studies had limited relevance, one on adolescents and one used CT not X ray. 2 studies could not be accessed. 3 studies gave sensitivity of X-ray between 6.5%-43.6% (+70% in adolescents) All studies gave specificity of X-rays at 100% All studies recommended MRI as the imaging modality of choice.

Clinical Bottom Line

X-ray is specific to stress fractures but not sensitive and therefore a negative x-ray should not rule out a stress fracture.

References

1. Laura M Fayad Distinction of long bone stress fractures from pathologic fractures on cross-sectional imaging: how successful are we? American Journal of Roentgenology 2005 Oct; 915-24,
2. Michele Gaeta CT and MR imaging findings in athletes with early tibial stress injuries: comparison with bone scintigraphy findings and emphasis on cortical abnormalities. Radiology 2005 May; 553-61:
3. V Boniotti Imaging of bone micro-injuries. La Radiologia medica 2003 May-Jun; 425-35:
4. A Feydy Longitudinal stress fractures of the tibia: comparative study of CT and MR imaging European radiology 1998; 598-602:
5. P Kasten [Diagnosis of stress fractures in adolescents] Sportverletzung Sportschaden: Organ der Gesellschaft fur Orthopadisch-Traumatologische Sportmedizin Dec 2005; 205-210: