Appelboam A, Reuben AD, Benger JR, Beech F, Dutson J, Haig S, et al. Elbow extension test to rule out elbow fracture: multicentre, prospective validation and observational study of diagnostic accuracy in adults and children. BMJ 2008;337:2428-32.
Question
In patients presenting with an elbow injury, does the elbow extension test accurately rule out bony injury?
A total of 2127 adults and children admitted to the emergency department with acute elbow injury.
Intervention
Elbow extension testing during routine care by clinical staff to determine the need for radiography in adults and to guide follow-up in children.
Outcomes
Presence of elbow fracture on radiograph or recovery with no indication for further review at 7 to 10 days.
Main Results
Of 1740 eligible participants, 602 patients were able to fully extend their elbow; 17 of these patients had a fracture. Two adult patients with olecranon fractures needed a change in treatment. In the 1138 patients without full elbow extension, 521 fractures were identified. Overall, the test had sensitivity of 96.8% (95% confidence interval 95.0 to 98.2) and specificity of 48.5% (95% CI, 45.6 to 51.4). Full elbow extension had a negative predictive value for fracture of 98.4% (96.3 to 99.5) in adults and 95.8% (92.6 to 97.8) in children. Negative likelihood ratios were 0.03 (0.01 to 0.08) in adults and 0.11 (0.06 to 0.19) in children.
Conclusions
The elbow extension test can be used in routine practice to inform clinical decision making. Patients who cannot fully extend their elbow after injury should be referred for radiography, because they have a nearly 50% chance of fracture. For those able to fully extend their elbow, radiography can be deferred if the practitioner is confident that an olecranon fracture (for adults) or a supracondylar fracture (for children) is not present. Patients who do not undergo radiography should return if symptoms have not resolved within 7 to 10 days.
Commentary
Clinical decision rules may help physicians practice cost-effective medicine, but unless the rules perform to an acceptable standard, the best we can hope for as clinicians are validated diagnostic tests. This is exactly how the “elbow extension test” should be viewed. Using clinically sound methods, Appleboam et al evaluate the performance of the test in a large number of children across a wide age range, representative of the typical practice in which such a test might be useful. For most physicians, though, including the authors, the sensitivity of 94.6% in children is not high enough to feel comfortable that a fracture has been “ruled out,” especially when considering the potential adverse outcomes of a missed supracondylar humerus fracture; by comparison, the Ottawa Ankle rules carry a pooled sensitivity of 98.5% in children.1 On the other hand, the clinician's toolbox now contains a validated clinical test for the pediatric elbow exam. Once other tests are developed and validated, the combination of multiple tests might result in an acceptable sensitivity to feel comfortable forgoing imaging. Alternatively, the combination of validated clinical and radiographic findings, such as the posterior fat pad sign,2 might be useful in determining the likelihood of an occult fracture, thus avoiding overtreatment and unnecessary advanced imaging. For now, the elbow extension test should be used as a tool, not a rule.
References
1. 1Dowling S, Spooner CH, Liang Y, Dryden DM, Friesen C, Klassen TP, et al.Accuracy of Ottawa Ankle Rules to exclude fractures of the ankle and midfoot in children: a meta-analysis. Acad Emerg Med. 2009;epub ahead of print.
2. 2Skaggs DL, Mirzayan R. The posterior fat pad sign in association with occult fracture of the elbow in children. J Bone Joint Surg Am. 1999;81:1429–1433. MEDLINE
University of Wisconsin, American Family Children's Hospital, Madison, Wisconsin
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